212 K.K. rajah Fig.8.3. Winterisation of cottonseed oil using horizontal crystallisers. (courtesy of CMB Bernadini, Italy) available for continuous filtration. If suitably prepared, the melting points of these stearins can be in the range 20-25C(Rossell, 1994) Cottonseed oil stearins can be an important source of zero trans fats which can substitute for hydrogenated fats, the latter being the subject of some concern in relation to trans fatty acids in the diet(applewhite 1994). They may find application in a variety of food formulations including margarines, soups and sauces. With annual world consumption of cottonseed oil currently at about 3.5 M tonnes, this potentially large source of zero trans fat is not being fully exploited. Ironically, much of the stearin from cottonseed oil goes into blends with soyabean oil which is then hydrogenated into hard stock for margarine and shortening manufacture. Since it is the hydrogenation reaction which is the main cause of trans fatty acids in processed fats, fractionation could well gain further importance as a means of generating zero trans hardstock, such as stearins from palm oil fractionation with melting points typically in the range 40-50C(Rossell, 1994) Fats which contain a large proportion of higher melting triacylglycerols, e. g. milk fat, palm oil and tallow, are treated to full fractionation where both fractions, i.e. stearins and oleins, are recovered in large amounts, typically 20-30% stearin and 70-80% olein Although manufacturers of fractionation equipment offer complete systems incorporating both the crystallisation tanks vell as the filtration units, the processes are generally referred to by the filtration system selected Three major filtration routes are available (a). flat-bed vacuum band filter; (b) rotary drum vacuum filter c)212 K. K. Rajah Fig. 8.3. Winterisation of cottonseed oil using horizontal crystallisers (courtesy of CMB Bernadini, Italy). available for continuous filtration. If suitably prepared, the melting points of these stearins can be in the range 20-25°C (Rossell, 1994). Cottonseed oil stearins can be an important source of zero trans fats which can substitute for hydrogenated fats, the latter being the subject of some concern in relation to trans fatty acids in the diet (Applewhite, 1994). They may find application in a variety of food formulations including margarines, soups and sauces. With annual world consumption of cottonseed oil currently at about 3.5 M tonnes, this potentially large source of zero trans fat is not being fully exploited. Ironically, much of the stearin from cottonseed oil goes into blends with soyabean oil which is then hydrogenated into hard stock for margarine and shortening manufacture. Since it is the hydrogenation reaction which is the main cause of trans fatty acids in processed fats, fractionation could well gain further importance as a means of generating zero trans hardstock, such as stearins from palm oil fractionation with melting points typically in the range 40-50°C (Rossell, 1994). Fats which contain a large proportion of higher melting triacylglycerols, e.g. milk fat, palm oil and tallow, are treated to full fractionation where both fractions, i.e. stearins and oleins, are recovered in large amounts, typically 20-30% stearin and 70-80% olein. Although manufacturers of fractionation equipment offer complete systems incorporating both the crystallisation tanks as well as the filtration units, the processes are generally referred to by the filtration system selected. Three major filtration routes are available: (a) flat-bed vacuum band filter; (b) rotary drum vacuum filter; (c) membrane, positive pressure filter