TECHNOLOGY OF CEREALS germination vary with uses. In grains destined caryopsis), which is a type of achene. all achenes for malting the requirement is for ready and are dry (rather than fleshy like many common vigorous germination as soon after harvest as fruits). All fruits, whether dry or fleshy typically possible but this must be combined with resistance contain one or more seeds. In the case of caryopses to sprouting, or premature germination prior to the number of fruits contained is one, and the able in all cereals, irrespective of their intended fruit when mature. It comprises accompanied by the production of hydrolytic 1. Embryonic axis enzymes which render stored nutrients in the 2. Scutellum endosperm soluble, thus reducing the amount of 3. Endosperm starch and protein harvested. Additionally the 4. Nucellus presence of high germination enzyme levels 5. Testa or seedcoat in cereals intended for flour production gives rise to excessive hydrolysis during processing Bread-making fours are particularly sensitive to such high enzyme levels as processing con- Aleurone ditions are well suited to enzyme-cataly Nucellus hydrolysis Germination is a complex syndrome, the detail of which are not fully understood. The important Pericarp events are shown in the flow diagram( Fig 2.15) beloy Grain anatom Scutellum The basic structural form of cereal caryopses is surprisingly consistent, to the extent that a FIG 2. 16 Generalized cereal grain, showing the relationships ' generalized cereal grain can be described(Fig. among the tissues. The proportions that they contribute, in individual cereals, are shown in Table 2.1 Although frequently referred to as seeds, cereal grains are in botanical terms fruits. The fruits Embryo of grasses are classified as caryopses(singula The embryonic axis and the scutellum together constitute the embryo. The embryonic axis is the plant of the next generation. It consists of pri mondial roots and shoot with leaf initials. It is Resting grair connected to and couched in the shield-like scutel If dormant lum, which lies between it and the endosperm change Hormones There is some confusion about the terminology of the embryo as the term is also used by Enzyme synthesis cereal chemists to describe part or all of the in endosperm embryo. If the botanical description is adopted Growth of roots proteins ati stof cet wot s, as above and germ'reserved for the embryo-rich then the FIG 2. 15 The main events involved in germination of a be no confusion The scutellum behaves as a ry and36 TECHNOLOGY OF CEREALS germination vary with uses. In grains destined for malting the requirement is for ready and vigorous germination as soon after harvest as possible but this must be combined with resistance to sprouting, Or Premature germination Prior to harvest. Resistance to sprouting is, in fact, desir￾able in all cereals, irrespective of their intended use, because the growth of the embryonic axis is accompanied by the production of hydrolytic enzymes which render stored nutrients in the endosperm soluble, thus reducing the amount of starch and protein harvested. Additionally the presence of high germination enzyme levels 5. Testa or seedcoat. in cereals intended for flour production gives rise to excessive hydrolysis during processing. Bread-making flours are particularly sensitive to such high enzyme levels as processing con￾ditions are well suited to enzyme-catalyzed hydrolysis. Germination is a complex syndrome, the details of which are not fully understood. The important events are shown in the flow diagram (Fig. 2.15) below. caryopsis), which is a type of achene. All achenes are dry (rather than fleshy like many common fruits). All fruits, whether dry or fleshy, typically contain one or more seeds. In the case of caryopses the number of fruits contained is one, and the seed accounts for the greater part of the entire fruit when mature. It comprises: 1. Embryonic axis; 2. Scutellum; 3. Endosperm; 4. Nucellus; Starchy endosperm Grain anatomy The basic structural form of cereal caryopses is surprisingly consistent, to the extent that a ‘generalized’ cereal grain can be described (Fig. FIG 2.16 Generalized cereal grain, showing the relationships among the tissues. The proportions that they contribute, in individual cereals, are shown in Table 2.1. 2.16). Although frequently referred to as seeds, cereal grains are in botanical terms fruits. The fruits of grasses are classified as caryopses (singular: Embryo The embryonic axis and the scutellum together constitute the embryo. The embryonic axis is the plant of the next generation. It consists of pri￾mordial roots and shoot with leaf initials. It is connected to and couched in the shield-like scutel￾lum, which lies between it and the endosperm. There is some confusion about the terminology of the embryo as the term ‘germ’ is also used by cereal chemists to describe part or all of the embryo. If the botanical description is adopted as above and ‘germ’ reserved for the embryo-rich fraction produced during milling, then there can be no confusion. The scutellum behaves as a secretory and Wote. Yxygen Resting grain If dormant no change iw ErnbryJ Horrnones 7 1 t L K%j~~r!hes’s Growth of roots and shoots Solublllzatlon of cel wals, proteins and starch FIG 2.15 The main events involved in germination of a seed