12 Quality and consumer acceptability S.R. P.R. Durand. hP Foods Ltd 12.1 Introduction Quality is an essential feature that will lead the consumer to select or not any food product. With numerous food scares that have hit the food market in the UK and Europe(E. coli, BSE, genetically modified organisms-based products, dioxins in animal feed in belgium) consumers have become much more aware and therefore selective in their choice to food Quality takes many aspects from safety to nutrition, sensory characteristics to service qualities. Consumers integrate these concepts to decide which product to buy according to their own criteria. A safe product is an essential requirement but will never suffice to sell a product Consumers want an attractive product in terms of organoleptic properties at a price they consider appropriate. It should satisfy their needs in terms of service provided(e.g. convenience, ease of opening)and more and more related to specific nutritional needs (vitamins, functional ingredients, low calories, low salt). In summary, quality is the combination of features in a product which ensure customer satisfaction From this definition of quality, it can be seen that customers will repeat the purchase of a chilled product if they are satisfied by its sensory quality, in one word if they are pleasurable to eat. Our senses are extremely sensitive and sophisticated to scrutinise our outside world. For example, our sense of smell, although not as sensitive as some other animal species, can detect hundreds of different odours. The topic of the first and second sections will give an overview of the way we measure quality of chilled products using our senses. It will also show how using a pool of people trained in the detection and description of sensory qualities will give the ability to product developers and quality managers to develop the best product, every time. However, understandi
12.1 Introduction Quality is an essential feature that will lead the consumer to select or not any food product. With numerous food scares that have hit the food market in the UK and Europe (E. coli, BSE, genetically modified organisms-based products, dioxins in animal feed in Belgium) consumers have become much more aware and therefore selective in their choice to food. Quality takes many aspects from safety to nutrition, sensory characteristics to service qualities. Consumers integrate these concepts to decide which product to buy according to their own criteria. A safe product is an essential requirement but will never suffice to sell a product. Consumers want an attractive product in terms of organoleptic properties at a price they consider appropriate. It should satisfy their needs in terms of service provided (e.g. convenience, ease of opening) and more and more related to specific nutritional needs (vitamins, functional ingredients, low calories, low salt). In summary, quality is the combination of features in a product which ensure customer satisfaction. From this definition of quality, it can be seen that customers will repeat the purchase of a chilled product if they are satisfied by its sensory quality, in one word if they are pleasurable to eat. Our senses are extremely sensitive and sophisticated to scrutinise our outside world. For example, our sense of smell, although not as sensitive as some other animal species, can detect hundreds of different odours. The topic of the first and second sections will give an overview of the way we measure quality of chilled products using our senses. It will also show how using a pool of people trained in the detection and description of sensory qualities will give the ability to product developers and quality managers to develop the best product, every time. However, understanding 12 Quality and consumer acceptability S. R. P. R. Durand, HP Foods Ltd
342 Chilled foods using trained people will only tell you one side of the story; how is a product characterised? In an increasingly competitive market, food manufacturers have realised the eed to ask their existing and potential customers what they like and dislike through preference tests. This will form the second side of the story and the ction dedicated to consumer acceptability will provide an exhaustive list of preference tests used to understand liking patterns. The final section will foc on combining these two sets of information, subjective and objective, to develop consumer-driven specifications that will fulfil their expectations 12.2 What defines sensory quality? The sensory quality of a product can be divided into its appearance, smell, texture. flavour and also aftertaste 12.2.1 Appearance The appearance of a product is the first assessment that a consumer will undertake to define the quality of a chilled product. Many aspects of the visual component of a food product can be used to assess its quality. The size, the shape the distribution of pieces, the surface texture, the colour and the brightness are all determining factors to assess freshness and overall quality expectation. The dullness or sheen of the surface in red meat combined with the redness of the flesh are used by consumers to assess the freshness of meat products in supermarkets. In return, supermarkets use lighting and in some instance spraying thin layer of water to improve the visual quality of meat behind counters The appearance can be divided into optical and visual structure components The optical appearance is mainly related to colour, gloss and translucency. The visual structure is linked to the texture of the product, including particle size, smoothness and surface texture. Colour is probably the first and main characteristic that a customer will use to judge the quality of a chilled product as the deterioration of food is often linked to a colour change(Piggott 1988) Colour is also involved with a psychological dimension; red is associated with power, orange and yellow with excitement and cheerfulness. The food industry is therefore spending a considerable amount of resources on eye-catching properties. In particular, farmed salmon are fed with carotenoids to give them a pink/orange colour, further enhanced when smoked, which is considered to be a sign of quality and freshness in the mind of the consumer 12.2.2 Odour: type, intensity The smell of chilled food gives a good indication of the freshness and quality An odour is detected when volatiles are inhaled into the nasal cavity and make contact with the olfactory system. Our smelling system is more modest equipment than our vision system, detecting only 10,000 odours with 5 million
quality using trained people will only tell you one side of the story; how is a chilled product characterised? In an increasingly competitive market, food manufacturers have realised the need to ask their existing and potential customers what they like and dislike through preference tests. This will form the second side of the story and the section dedicated to consumer acceptability will provide an exhaustive list of preference tests used to understand liking patterns. The final section will focus on combining these two sets of information, subjective and objective, to develop consumer-driven specifications that will fulfil their expectations. 12.2 What defines sensory quality? The sensory quality of a product can be divided into its appearance, smell, texture, flavour and also aftertaste. 12.2.1 Appearance The appearance of a product is the first assessment that a consumer will undertake to define the quality of a chilled product. Many aspects of the visual component of a food product can be used to assess its quality. The size, the shape, the distribution of pieces, the surface texture, the colour and the brightness are all determining factors to assess freshness and overall quality expectation. The dullness or sheen of the surface in red meat combined with the redness of the flesh are used by consumers to assess the freshness of meat products in supermarkets. In return, supermarkets use lighting and in some instance spraying a thin layer of water to improve the visual quality of meat behind counters. The appearance can be divided into optical and visual structure components. The optical appearance is mainly related to colour, gloss and translucency. The visual structure is linked to the texture of the product, including particle size, smoothness and surface texture. Colour is probably the first and main characteristic that a customer will use to judge the quality of a chilled product, as the deterioration of food is often linked to a colour change (Piggott 1988). Colour is also involved with a psychological dimension; red is associated with power, orange and yellow with excitement and cheerfulness. The food industry is therefore spending a considerable amount of resources on eye-catching properties. In particular, farmed salmon are fed with carotenoids to give them a pink/orange colour, further enhanced when smoked, which is considered to be a sign of quality and freshness in the mind of the consumer. 12.2.2 Odour: type, intensity The smell of chilled food gives a good indication of the freshness and quality. An odour is detected when volatiles are inhaled into the nasal cavity and make contact with the olfactory system. Our smelling system is more modest equipment than our vision system, detecting only 10,000 odours with 5 million 342 Chilled foods
Quality and consumer acceptability 343 of colours with more than 100 million receptors (Meilgaard It is however highly efficient in the detection of spoilage, Irs or taint and often more sensitive and accurate than many sophisticated instruments. When cutting a piece of meat or fish, the level of freshness can be assessed by smell. Jorgensen et al.(1988)has shown a strong relationship between the detection of malodorous volatiles and the spoilage of chilled fish during shelf-life as detected by a pool of trained people 12.2.3 Flavour Flavour is possibly the essential sensory component used to measure the quality of chilled products. If the flavour is undesirable or does not correspond to expectations, the product will be rejected. Flavour is defined as the sum of perceptions perceived in the mouth in the back of the throat and the nose via the retro-nasal route(Piggott 1988). Flavour includes the primary tastes(salty, sweet, acidic and bitter) caused by soluble substances, sensation factors such as astringency, heat or cooling effects and the aroma perception caused by volatile lbstances. Quality criteria associated with flavour relate to the expression of an expected flavour and the intensity of it. 12.2. 4 Texture Texture can be defined as the sensory perception on the physical structure of a food product. During the handling and preparation of food, texture properties can be measured by visual evaluation and touch to identify its overall quality. A hard cheese over matured will look dry with a sensation of mouthdrying and roughness in the mouth. Cheese makers use an agreed methodology to define the quality of cheese in relation to its texture characteristics exture is a complex area of the evaluation of sensory quality, as described and classified in reviews by Bourne(1982) or Civille and Liska(1975). There are three different texture characteristics 1. The mechanical dimension is related to the reaction of the food to stress such as hardness, firmness, cohesiveness or chewiness, as measured by the muscles of the hand, fingers, lips, tongue or jaw. 2. The geometrical dimension is related to the arrangement of the physical components of a product such as size, shape, fibrousness, particles or lumps 3. The surface dimension is related to the moisture and fat content of a product and how they are released during a chewing process A large part of enjoying a meat product involves its texture quality and consumers are well aware of words such as tenderness chewiness or toughnes Slaughtering methods and storage conditions have an influence on the texture quality of fresh fish as described by Love(1988). For pastry-based products such as quiche or pizza, texture is the criterion that influences and therefore best
receptors, versus millions of colours with more than 100 million receptors (Meilgaard et al. 1987). It is however highly efficient in the detection of spoilage, off-odours or taint and often more sensitive and accurate than many sophisticated instruments. When cutting a piece of meat or fish, the level of freshness can be assessed by smell. Jorgensen et al. (1988) has shown a strong relationship between the detection of malodorous volatiles and the spoilage of chilled fish during shelf-life as detected by a pool of trained people. 12.2.3 Flavour Flavour is possibly the essential sensory component used to measure the quality of chilled products. If the flavour is undesirable or does not correspond to expectations, the product will be rejected. Flavour is defined as the sum of perceptions perceived in the mouth in the back of the throat and the nose via the retro-nasal route (Piggott 1988). Flavour includes the primary tastes (salty, sweet, acidic and bitter) caused by soluble substances, sensation factors such as astringency, heat or cooling effects and the aroma perception caused by volatile substances. Quality criteria associated with flavour relate to the expression of an expected flavour and the intensity of it. 12.2.4 Texture Texture can be defined as the sensory perception on the physical structure of a food product. During the handling and preparation of food, texture properties can be measured by visual evaluation and touch to identify its overall quality. A hard cheese over matured will look dry with a sensation of mouthdrying and roughness in the mouth. Cheese makers use an agreed methodology to define the quality of cheese in relation to its texture characteristics. Texture is a complex area of the evaluation of sensory quality, as described and classified in reviews by Bourne (1982) or Civille and Liska (1975). There are three different texture characteristics. 1. The mechanical dimension is related to the reaction of the food to stress, such as hardness, firmness, cohesiveness or chewiness, as measured by the muscles of the hand, fingers, lips, tongue or jaw. 2. The geometrical dimension is related to the arrangement of the physical components of a product such as size, shape, fibrousness, particles or lumps. 3. The surface dimension is related to the moisture and fat content of a product and how they are released during a chewing process. A large part of enjoying a meat product involves its texture quality and consumers are well aware of words such as tenderness, chewiness or toughness. Slaughtering methods and storage conditions have an influence on the texture quality of fresh fish as described by Love (1988). For pastry-based products such as quiche or pizza, texture is the criterion that influences and therefore best Quality and consumer acceptability 343
344 Chilled foods its quality. The pastry tends to adsorb moistness from the other ents to become soggy prior to any development of off-flavour 12.3 Sensory evaluation techniques From the previous section, it is obvious that any test to measure quality of chilled food should involve the use of human subjects Sensory evaluation is a scientific discipline involved with the measure study and interpretation of responses to food properties as perceived by the senses of sight, smell, taste, touch and hearing(IFT 1975) ensory assessment is done either by a small pool of people( typically 8 to 30 people)who have received some training, known asobjective testing or by a larger pool of consumers who give their own opinion on a product or range of products without any prior training. This is known as'subjective testing. The objective and hypotheses defined in any project brief will determine the choice of the type of valuation to be performed, and the type of panel, the test and the overall design of the experiment. Carpenter et al.(2000) defines in detail the criteria to consider Objective testing is carried out by qualified and trained people and can be used for discriminating and describing differences between chilled products This pool of people, or sensory panel, can be employees of a company or a dedicated workforce. After initial recruitment to measure any sensory impairment such as anosmia (impairment in the sense of smell) or ageusia (impairment in the sense of taste), the panel members take part in an extensive and gradually more difficult training schedule in order to describe, discriminate and evaluate any subtle differences between the products under investigation Many sensory professionals have published training schedules for general aining sessions Jellinek 1985) to more specific and precise sensory programmes( Civille and Szczesniak 1975). Tests used to characterise food properties by sensory experts can be either discriminative or descriptive 12.3.1 Discriminative tests These types of tests are used when it is required to identify if any difference exists between two or more products. It might be required to change an ingredient supplier for cost reduction or quality reasons and the brief is to confirm that the overall flavour, texture or appearance is not affected. It is more cost effective to ask a highly trained panel of experts in their field to assess any difference rather than asking consumers. The tests are very sensitive to any direct most commonly used discriminative test. In this test, panellists are given three mples, in a pre-determined order, one is different from the other two. They are asked to identify the odd sample(BS 5929: part 5, 1988). For example, a ham manufacturer might want to assess the effectiveness of a controlled atmosphere packaging against a present system without changing the overall sensory
predicts its quality. The pastry tends to adsorb moistness from the other components to become soggy prior to any development of off-flavour. 12.3 Sensory evaluation techniques From the previous section, it is obvious that any test to measure quality of chilled food should involve the use of human subjects. Sensory evaluation is a scientific discipline involved with the measure, study and interpretation of responses to food properties as perceived by the senses of sight, smell, taste, touch and hearing (IFT 1975). Sensory assessment is done either by a small pool of people (typically 8 to 30 people) who have received some training, known as ‘objective testing’ or by a larger pool of consumers who give their own opinion on a product or range of products without any prior training. This is known as ‘subjective testing’. The objective and hypotheses defined in any project brief will determine the choice of the type of evaluation to be performed, and the type of panel, the test and the overall design of the experiment. Carpenter et al. (2000) defines in detail the criteria to consider. Objective testing is carried out by qualified and trained people and can be used for discriminating and describing differences between chilled products. This pool of people, or sensory panel, can be employees of a company or a dedicated workforce. After initial recruitment to measure any sensory impairment such as anosmia (impairment in the sense of smell) or ageusia (impairment in the sense of taste), the panel members take part in an extensive and gradually more difficult training schedule in order to describe, discriminate and evaluate any subtle differences between the products under investigation. Many sensory professionals have published training schedules for general training sessions (Jellinek 1985) to more specific and precise sensory programmes (Civille and Szczesniak 1975). Tests used to characterise food properties by sensory experts can be either discriminative or descriptive. 12.3.1 Discriminative tests These types of tests are used when it is required to identify if any difference exists between two or more products. It might be required to change an ingredient supplier for cost reduction or quality reasons and the brief is to confirm that the overall flavour, texture or appearance is not affected. It is more cost effective to ask a highly trained panel of experts in their field to assess any difference rather than asking consumers. The tests are very sensitive to any sensory variation as they involve a direct comparison. The triangle test is the most commonly used discriminative test. In this test, panellists are given three samples, in a pre-determined order, one is different from the other two. They are asked to identify the odd sample (BS 5929: part 5, 1988). For example, a ham manufacturer might want to assess the effectiveness of a controlled atmosphere packaging against a present system without changing the overall sensory 344 Chilled foods
Quality and consumer acceptability 345 properties over time. The test sensitivity can allow expensive capital expenditure requirements to be made with a high level of confidence When more than two products are compared, ranking tests comparison tests are used. Typically, a ranking test is used when no control is available or required and assessors are asked to rank products in order of intensity for a specific sensory characteristic. A multiple comparison test is used when a control sample is used as an anchor point and assessors are asked to evaluate the intensity of the difference if any Other tests might be required from time to time to evaluate the sensitivity of specific compounds and/or chemicals. These tests are important in taint evaluation or the detection of materials difficult to assess. Threshold tests are used to detect at which concentration level, a compound can be detected Dilution technique determines the smallest amount of compound that can be detected in a product. Gillette et al. (1984)use this technique to assess the level of heat in red peppers 12.3.2 Descriptive tests These tests are used to identify sensory characteristics of a chilled product and quantify them. Panellists are selected on their ability to describe and discriminate between samples. They are presented with variants of the product and asked to describe them. After a period dedicated to confirm and define agreed terms and scale, the panel is then presented with the samples, one at a time and asked to give a score. Stone et al. (1974) has described in detail one of these descriptive techniques calledquantitative descriptive analysis. Results are analysed by means of univariate and multivariate analyses. Analysis of variance(O"Mahony 1986) is used to measure any difference between samples for each attribute Principal component analysis is a technique used to reduce the amount of dimension or sensory terms into a manageable format, usually two or three dimensions. Procustes analysis is mainly used for the assessment of individuals performance and efficiency(Arnold and Williams 1986). Graphs are often used to summarise the results into condensed and meaningful information. Spider graphs(see Fig. 12.1), give a general overview of sensory differences by th overall shape of each product, providing an individual product fingerprint. Other sensory techniques have emerged in recent years in the evaluation of food quality by sensory evaluation. In particular, the time-intensity technique takes into consideration the temporal dimension of tasting behaviour( Cliff et al. 1993). This technique is particularly interesting for the assessment of spicy oroducts or for primary taste evaluation, such as sweet sensation in artificially sweetened drinks and is used by Matysiak and Noble(1991) Figure 12.1 shows an overview of how four samples of chilled smoked salmon differ in sensory terms from one another, using a spider graph. For each attribute, the samples are more intense away from the centre. In particular salmon d had a more orangy colour and sample F had the least moist surface Sample I was the least salty and smoky produc
properties over time. The test sensitivity can allow expensive capital expenditure requirements to be made with a high level of confidence. When more than two products are compared, ranking tests or multiple comparison tests are used. Typically, a ranking test is used when no control is available or required and assessors are asked to rank products in order of intensity for a specific sensory characteristic. A multiple comparison test is used when a control sample is used as an anchor point and assessors are asked to evaluate the intensity of the difference if any. Other tests might be required from time to time to evaluate the sensitivity of specific compounds and/or chemicals. These tests are important in taint evaluation or the detection of materials difficult to assess. Threshold tests are used to detect at which concentration level, a compound can be detected. Dilution technique determines the smallest amount of compound that can be detected in a product. Gillette et al. (1984) use this technique to assess the level of heat in red peppers. 12.3.2 Descriptive tests These tests are used to identify sensory characteristics of a chilled product and to quantify them. Panellists are selected on their ability to describe and discriminate between samples. They are presented with variants of the product and asked to describe them. After a period dedicated to confirm and define agreed terms and scale, the panel is then presented with the samples, one at a time and asked to give a score. Stone et al. (1974) has described in detail one of these descriptive techniques called ‘quantitative descriptive analysis’. Results are analysed by means of univariate and multivariate analyses. Analysis of variance (O’Mahony 1986) is used to measure any difference between samples for each attribute. Principal component analysis is a technique used to reduce the amount of dimension or sensory terms into a manageable format, usually two or three dimensions. Procustes analysis is mainly used for the assessment of individuals’ performance and efficiency (Arnold and Williams 1986). Graphs are often used to summarise the results into condensed and meaningful information. Spider graphs (see Fig. 12.1), give a general overview of sensory differences by the overall shape of each product, providing an individual product fingerprint. Other sensory techniques have emerged in recent years in the evaluation of food quality by sensory evaluation. In particular, the time-intensity technique takes into consideration the temporal dimension of tasting behaviour (Cliff et al., 1993). This technique is particularly interesting for the assessment of spicy products or for primary taste evaluation, such as sweet sensation in artificially sweetened drinks and is used by Matysiak and Noble (1991). Figure 12.1 shows an overview of how four samples of chilled smoked salmon differ in sensory terms from one another, using a spider graph. For each attribute, the samples are more intense away from the centre. In particular, salmon D had a more orangy colour and sample F had the least moist surface. Sample I was the least salty and smoky product. Quality and consumer acceptability 345
346 Chilled foods Smell characteristic Flake size D Orange intensity Smoky flavour Surface moistness Firm Ease of cutting Fig. 12.1 Differences in sensory profile between four different chilled smoked salmon. 12.3.3 Use of a trained panel for measurement of sensory quality Taint and off-flavours In foods these are a major threat to manufacturers and retailers, as it can become extremely dam d costly. a tainted product reaching the consumer can create problems for the food producer or retailer much more damaging than the complaint itself. Direct costs such as loss of production, cleaning of factory damaged commercial relationships between suppliers, manufacturers and retailers (e.g. de-listing by retailers), litigation proceedings and even factory shutdown may occur. Other more substantial financial implications may arise such as loss of customer goodwill and damaged brand image may manifest themselves through lower sales and loss of market share. Taint and off-flavours are caused by the presence of a chemical at very low concentration in a food product, usually a volatile organic compound, which imparts a flavour unacceptable to the consumer. Taint is an unpleasant odour or flavour imparted to food through external sources and off-flavour(or off-odour)is an unpleasant flavour (or odour) to food through internal changes, such as enzymatic or microbial activities. Unlimited sources of taint and off-flavours exist making it extremely difficult for manufacturers or retailers to control. Raw materials, packaging materials, factory environment (e.g. flooring, paint, cleaning agents), microbial spoilage are all known sources of taint and off-flavour. Water can also be a major source of contamination. It may contain chlorophenols or chloroanisol: this accounts for the largest number of known cases of taint ensory evaluation coupled with the use of sophisticated apparatus such as Gas Chromatography Mass Spectrometry (GCMS) is required to evaluate and identify the taint and its source. Such a combination was used by Farmer et al. (1995) to evaluate off-flavours in wild and farmed Atlantic salmon. The author found that the main difference was between wild salmon caught in rivers and those from the sea rather than between wild and farmed salmon. River-caught
12.3.3 Use of a trained panel for measurement of sensory quality Taint and off-flavours In foods these are a major threat to manufacturers and retailers, as it can become extremely damaging and costly. A tainted product reaching the consumer can create problems for the food producer or retailer much more damaging than the complaint itself. Direct costs such as loss of production, cleaning of factory, damaged commercial relationships between suppliers, manufacturers and retailers (e.g. de-listing by retailers), litigation proceedings and even factory shutdown may occur. Other more substantial financial implications may arise, such as loss of customer goodwill and damaged brand image may manifest themselves through lower sales and loss of market share. Taint and off-flavours are caused by the presence of a chemical at very low concentration in a food product, usually a volatile organic compound, which imparts a flavour unacceptable to the consumer. Taint is an unpleasant odour or flavour imparted to food through external sources and off-flavour (or off-odour) is an unpleasant flavour (or odour) to food through internal changes, such as enzymatic or microbial activities. Unlimited sources of taint and off-flavours exist making it extremely difficult for manufacturers or retailers to control. Raw materials, packaging materials, factory environment (e.g. flooring, paint, cleaning agents), microbial spoilage are all known sources of taint and off-flavour. Water can also be a major source of contamination. It may contain chlorophenols or chloroanisol; this accounts for the largest number of known cases of taint. Sensory evaluation coupled with the use of sophisticated apparatus such as Gas Chromatography Mass Spectrometry (GCMS) is required to evaluate and identify the taint and its source. Such a combination was used by Farmer et al. (1995) to evaluate off-flavours in wild and farmed Atlantic salmon. The author found that the main difference was between wild salmon caught in rivers and those from the sea rather than between wild and farmed salmon. River-caught Fig. 12.1 Differences in sensory profile between four different chilled smoked salmon. 346 Chilled foods
Quality and consumer acceptability 347 wild salmon showed enhanced earthy flavour and odour notes, with 2- methylisoborneol and geosmin being the major compounds involved Se itoring of quality The quality of chilled products should be consistent during production and food companies are using various techniques to ensure food quality conformity These techniques have a common ground in that one or more parameters are measured against an agreed quality specification. For example, pH, salt or sugar levels might be measured to ensure no drift to the final composition of a product. These measurements, although important in their own right, will not allow the definition of flavour characteristic or texture quality. Sensory evaluation is therefore used to ensure integrity of a series of set quality parameters. The stages involved in setting up such routine sensory quality monitoring include the establishment of a product standard that represents the ustomer requirements. The product standard is translated into key sensory characteristics. The second stage involves the definition of acceptance ranges for each parameter, taking into account commercial risks against consumer loyalty. In the case of sensory quality assessment, a panel is selected and trained to recognise products that fall within and outside the acceptable range or each sensory parameter. It is essential that employees involved are committed to quality and that more than one assessor is used for each assessment to ensure precision and reliability. Standard procedures are set and may include go/no-go quality rating or grading such as the CCFRA frozen and canned products specification(Rodway et al. 1999), difference test or more precise but lengthy descriptive analysis A specification sheet that includes acceptance ranges (Table 12. 1)and a quality monitoring chart for a flavour parameter(Fig. 12. 2)are provided as an example for the assessment of the quality of a chilled apple pie. The members of a panel are asked individually to assess each sample for each attribute using a 10-point scale, from not present to very strong. A consensus score or mean score is then entered into the collation sheet showing the non-acceptable range for each attribute(shaded areas). One or more scores outside the non-shaded area indicate a product that does not meet quality criteria and further investigation is required to confirm the findings. Figure 12.2 displays the trend of the change of strength of flavour characteristic for a chilled apple pie product over a production time span of six months. For each production batch evaluated, a score outside the two specification limits is considered as unacceptable. The strength of flavour varies considerably over this production period and an investigation should be organised to understand reasons for this variability and how to correct it Storage effect/definition of shelf-life Shelf-life of chilled products can be defined as the period between manufacture and consumption during which the product is in an acceptable condition, both in
wild salmon showed enhanced earthy flavour and odour notes, with 2- methylisoborneol and geosmin being the major compounds involved. Sensory monitoring of quality The quality of chilled products should be consistent during production and food companies are using various techniques to ensure food quality conformity. These techniques have a common ground in that one or more parameters are measured against an agreed quality specification. For example, pH, salt or sugar levels might be measured to ensure no drift to the final composition of a product. These measurements, although important in their own right, will not allow the definition of flavour characteristic or texture quality. Sensory evaluation is therefore used to ensure integrity of a series of set quality parameters. The stages involved in setting up such routine sensory quality monitoring include the establishment of a product standard that represents the customer requirements. The product standard is translated into key sensory characteristics. The second stage involves the definition of acceptance ranges for each parameter, taking into account commercial risks against consumer loyalty. In the case of sensory quality assessment, a panel is selected and trained to recognise products that fall within and outside the acceptable range for each sensory parameter. It is essential that employees involved are committed to quality and that more than one assessor is used for each assessment to ensure precision and reliability. Standard procedures are set up and may include go/no-go quality rating or grading such as the CCFRA frozen and canned products specification (Rodway et al. 1999), difference test or more precise but lengthy descriptive analysis. A specification sheet that includes acceptance ranges (Table 12.1) and a quality monitoring chart for a flavour parameter (Fig. 12.2) are provided as an example for the assessment of the quality of a chilled apple pie. The members of a panel are asked individually to assess each sample for each attribute using a 10-point scale, from not present to very strong. A consensus score or mean score is then entered into the collation sheet showing the non-acceptable range for each attribute (shaded areas). One or more scores outside the non-shaded area indicate a product that does not meet quality criteria and further investigation is required to confirm the findings. Figure 12.2 displays the trend of the change of strength of flavour characteristic for a chilled apple pie product over a production time span of six months. For each production batch evaluated, a score outside the two specification limits is considered as unacceptable. The strength of flavour varies considerably over this production period and an investigation should be organised to understand reasons for this variability and how to correct it. Storage effect/definition of shelf-life Shelf-life of chilled products can be defined as the period between manufacture and consumption during which the product is in an acceptable condition, both in Quality and consumer acceptability 347
348 Chilled foods Table 12.1 Specification sheet for collation of data for flavour and texture of chilled apple Strength of apple Sweetness Off-flavours Texture Doughiness of pastry Greasy mouthfeel 二地m Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 Fig. 12.2 Quality monitoring over a six month period for stre our of a chilled apple pie. terms of safety and quality. During storage, a chilled product will undergo hanges linked to chemical, microbiological and physical reactions. It has been shown that for many products, sensory evaluation has proven to be the most sensitive technique to assess these changes. Similar techniques to those described for quality monitoring can be applied to sensory shelf-life evaluation Claasen and Lawless (1992) found that sensory analysis by descriptive technique to measure the end of life of liquid milk was more sensitive than more traditional analytical techniques
terms of safety and quality. During storage, a chilled product will undergo changes linked to chemical, microbiological and physical reactions. It has been shown that for many products, sensory evaluation has proven to be the most sensitive technique to assess these changes. Similar techniques to those described for quality monitoring can be applied to sensory shelf-life evaluation. Claasen and Lawless (1992) found that sensory analysis by descriptive technique to measure the end of life of liquid milk was more sensitive than more traditional analytical techniques. Table 12.1 Specification sheet for collation of data for flavour and texture of chilled apple pie Flavour 0 123456789 Strength of apple Sweetness Acidic Oily/fatty pastry Off-flavours Texture Doughiness of pastry Crispness of apple Greasy mouthfeel Fig. 12.2 Quality monitoring over a six month period for strength of flavour of a chilled apple pie. 348 Chilled foods Strength apple flavor Upper specification Lower specification
Quality and consumer acceptability 349 12.4 Determining consumer acceptability There is no doubt that the taste of food is an essential criterion for the acceptability of a product by the consumer. The best marketing and advertising campaign for a new chilled product might convince a consumer to buy it for the first time. However, should this product not attain expected values, the consumer will not purchase the product again. Although taste undoubtedly plays an important part in food choice, it is not the only essential element. Attitudes, belief, nutritional awareness, brand and image, convenience, price and other socio-cultural aspects(e.g. religion, education) are all important criteria the market researcher will take into account. Although expert sensory panels are useful to understand the sensory properties of a chilled product, when consumer acceptability and behaviour is concerned, tests involving consumers must take place 12.4.1 On-site trials for screening purposes These tests are used by many food companies to assess the sensory quality of their products, including products under development versus competitors'ones These tests are very useful for the screening of several samples prior to a full- scale assessment, in order to reduce costs and optimise tight deadlines. A minimum number of consumers are required in order to be confident of the result. It is advisable to involve at least 50 employees. The main negative aspect to this type of assessment is the knowledge employees have acquired working in contact with the product and inevitably biases may occur in their choice. The archer should minimise these biases hiding recognisable clues when 12.4.2 Home placement tests hese tests imply that consumers are asked to try and assess one or more products while at home. The advantage is that the assessment is carried out within a normal life situation and is therefore more likely to represent the true behaviour and liking for a product. It also has the advantage of getting an opinion from the whole family rather than just one individual. However, the drawback is that the control of the response is poor. In particular, different ooking procedures and processes may be used by different consumers, making a direct comparison more complicated. Also, when two or more products are assessed, the cooking procedure between products or the time interval between cooking and eating may differ In a home location test, samples may be delivered to homes or collected at a central location. After a certain period, the researcher will interview the consumer by phone or face-to-face by calling in. Questions such as liking for each product by each member of the household, type of cooking and serving, expectation, likelihood of purchase may be asked
12.4 Determining consumer acceptability There is no doubt that the taste of food is an essential criterion for the acceptability of a product by the consumer. The best marketing and advertising campaign for a new chilled product might convince a consumer to buy it for the first time. However, should this product not attain expected values, the consumer will not purchase the product again. Although taste undoubtedly plays an important part in food choice, it is not the only essential element. Attitudes, belief, nutritional awareness, brand and image, convenience, price and other socio-cultural aspects (e.g. religion, education) are all important criteria the market researcher will take into account. Although expert sensory panels are useful to understand the sensory properties of a chilled product, when consumer acceptability and behaviour is concerned, tests involving consumers must take place. 12.4.1 On-site trials for screening purposes These tests are used by many food companies to assess the sensory quality of their products, including products under development versus competitors’ ones. These tests are very useful for the screening of several samples prior to a fullscale assessment, in order to reduce costs and optimise tight deadlines. A minimum number of consumers are required in order to be confident of the result. It is advisable to involve at least 50 employees. The main negative aspect to this type of assessment is the knowledge employees have acquired working in contact with the product and inevitably biases may occur in their choice. The researcher should minimise these biases hiding recognisable clues when possible. 12.4.2 Home placement tests These tests imply that consumers are asked to try and assess one or more products while at home. The advantage is that the assessment is carried out within a normal life situation and is therefore more likely to represent the true behaviour and liking for a product. It also has the advantage of getting an opinion from the whole family rather than just one individual. However, the drawback is that the control of the response is poor. In particular, different cooking procedures and processes may be used by different consumers, making a direct comparison more complicated. Also, when two or more products are assessed, the cooking procedure between products or the time interval between cooking and eating may differ. In a home location test, samples may be delivered to homes or collected at a central location. After a certain period, the researcher will interview the consumer by phone or face-to-face by calling in. Questions such as liking for each product by each member of the household, type of cooking and serving, expectation, likelihood of purchase may be asked. Quality and consumer acceptability 349
350 Chilled foods 12.4.3 Central location or hall tests When a consumer test must be controlled more closely, or the number of products exceeds two or three, a central location test in busy town centres preferred. Interviewers stop potential participants and ask specific questions to that they meet agreed criteria, i.e. that they fall within set quotas and to ensure their willingness to participate. This test tends to be preferred by food companies for being cheaper to run than home location tests. Hedonic scales are usually used to measure liking of products. Consumers are asked their liking for will dictate the type of samples to be assessed and the questions asked Search each product and also the preferred sample overall. The objective of the re 2.4.4 Food choice and attitude he above techniques all use hedonic scales that mainly reflect the preference for the product. However, when one is interested in the reasons for choosing certain foods, it is important to encompass other components to determine attitude towards foods. In particular, the cognitive and intention components Many researchers have tried to incorporate more than one factor to explain what dictates choice. When consumers want to treat themselves to a high-quality piece of meat, they may be more inclined to go to a local butcher and select, often after discussion and advice, a quality sirloin steak The experience of buying and the context in which it is carried out becomes an integral part of the decision process and choice. Lange(1999)studied how name and packaging information could affect orange juice liking under mical constraint. The author observed differences between hedonic responses under blind conditions when various information and economical constraints were given. Other researchers have investigated the influence of health and nutrition information on liking (Kahkonen and tuorila 1995) Contextual analysis has been extensively studied by Schutz(1994)to identify how, when, where and by whom specific food products are eaten 2.4.5 Qualitative research Qualitative research is carried out when the objective of the study is to understand behaviour and attitude rather than preference, although a combination of both is often considered. Focus groups and individual interviews are two types of qualitative techniques. In a focus group test, eight to ten consumers are recruited and asked to participate in a discussion around a specific topic. To manage such a group, a moderator is used who leads the discussion using specific elicitation chniques to gain information related to the topic. In particular, it is useful to use open-ended questions and probing questions to get the most useful information from the group. A carefully prepared questioning plan is used by the moderator to guide the discussion towards the main areas of interest. n a recent study, a focus group technique was used to investigate whether a new concept of pre-cooked bacon would succeed in the market-place. Reactions
12.4.3 Central location or hall tests When a consumer test must be controlled more closely, or the number of products exceeds two or three, a central location test in busy town centres is preferred. Interviewers stop potential participants and ask specific questions to ensure that they meet agreed criteria, i.e. that they fall within set quotas and to ensure their willingness to participate. This test tends to be preferred by food companies for being cheaper to run than home location tests. Hedonic scales are usually used to measure liking of products. Consumers are asked their liking for each product and also the preferred sample overall. The objective of the research will dictate the type of samples to be assessed and the questions asked. 12.4.4 Food choice and attitude The above techniques all use hedonic scales that mainly reflect the preference for the product. However, when one is interested in the reasons for choosing certain foods, it is important to encompass other components to determine attitude towards foods. In particular, the cognitive and intention components. Many researchers have tried to incorporate more than one factor to explain what dictates choice. When consumers want to treat themselves to a high-quality piece of meat, they may be more inclined to go to a local butcher and select, often after discussion and advice, a quality sirloin steak. The experience of buying and the context in which it is carried out becomes an integral part of the decision process and choice. Lange (1999) studied how name and packaging information could affect orange juice liking under economical constraint. The author observed differences between hedonic responses under blind conditions when various information and economical constraints were given. Other researchers have investigated the influence of health and nutrition information on liking (Ka¨hko¨nen and Tuorila 1995). Contextual analysis has been extensively studied by Schutz (1994) to identify how, when, where and by whom specific food products are eaten. 12.4.5 Qualitative research Qualitative research is carried out when the objective of the study is to understand behaviour and attitude rather than preference, although a combination of both is often considered. Focus groups and individual interviews are two types of qualitative techniques. In a focus group test, eight to ten consumers are recruited and asked to participate in a discussion around a specific topic. To manage such a group, a moderator is used who leads the discussion using specific elicitation techniques to gain information related to the topic. In particular, it is useful to use open-ended questions and probing questions to get the most useful information from the group. A carefully prepared questioning plan is used by the moderator to guide the discussion towards the main areas of interest. In a recent study, a focus group technique was used to investigate whether a new concept of pre-cooked bacon would succeed in the market-place. Reactions 350 Chilled foods