The nutritional quality of cereals and the sensorial properties of their products are sometimes inferior as compared to other sources of food which is due to the lower protein content and starch availability, the presence of determined antinutrients (phytic acid, tannins, and polyphenols) and the coarse nature of the grains. To ameliorate the nutritional qualities of cereals, they are processed in a number of ways. This review summarizes the enhancement in the nutritional value as well as the functional characteristics of cereals due to germination and fermentation treatment. The protein concentration increases and the amino acid profile is balanced by germination and fermentation. The antinutritional factors are reduced increasing the mineral availability from the cereals. Germination enhances the quality of nutrients and bioactive compounds of cereals thereby increasing the content in proteins, amino acids, sugars, and vitamins. The functional properties of cereals is enhanced due to generation of biofunctional substances, increase in protein solubility, in vitro protein digestibility and lowering of glycemic index.
Ohmic heating, also known as Joule heating, electrical resistance heating, and direct electrical resistance heating, is a process of heating the food by passing electric current. In ohmic heating the energy is dissipated directly into the food. Electrical conductivity is a key parameter in the design of an effective ohmic heater. A large number of potential applications exist for ohmic heating, including blanching, evaporation, dehydration, fermentation, sterilization, pasteurization, and heating of foods. Beyond heating, applied electric field under ohmic heating causes electroporation of cell membranes, which increase extraction rates, and reduce gelatinization temperature and enthalpy. Ohmic heating results in faster heating of food along with maintenance of color and nutritional value of food. Water absorption index, water solubility index, thermal properties, and pasting properties are altered with the application of ohmic heating. Ohmic heating results in pre-gelatinized starches, which reduce energy requirement during processing. But its higher initial cost, lack of its applications in foods containing fats and oils, and less awareness limit its use.
Germination of legumes is potential bioprocessing technique to improve the nutrient digestibility and enhancement of bioactive components. The present investigation studies the effects of different germination conditions on the bioactive components, antioxidant activity, and in vitro nutrient digestibility of pigeon pea. Results obtained indicated that increase in germination time and temperature modifies the bioactive components and nutritional digestibility of the pigeon pea. Studies have shown that increase in germination time from 12 to 48 hr and temperature from 25 to 35°C, results in significant increase in accumulation of total pheolics and flavonoid content as a result of cell wall degrading enzymes. Germination for prolonged time at higher temperature also significantly increases the antioxidant potential and reducing power of the germinated pigeon pea. Increased activity of hydrolytic enzymes alters the structure of starch and proteins and thus enhanced in vitro starch and protein digestibility and also lowers down the hot paste viscosity of germinated pigeon pea.
Practical applications
Currently, consumers are increasingly interested in high‐quality natural health foods with high biological value and better nutrient digestibility. Germinated grains legumes become popular among people engrossed in improving and maintaining their health by changing dietary habits. Germinated pigeon pea exhibited better nutrient digestibility with improved texture and flavor, higher antioxidant activity and more bioactive components with lower pasting viscosity due to enzymatic modification of starch and protein in the grain. For this reason, use of germinated pigeon pea flour can provide an excellent example of functional food with high dietary protein value. Germinated pigeon pea flour can be utilized as a functional ingredient in the preparation of novel function foods, and it would intensify metabolism, strengthen immunity, reimburse deficiencies of vitamins and mineral, lower the risk of various diseases and exert health‐promoting effects.
Grain activation is a natural processing technique that can be used to produce modified flours without chemical modification. Functional characteristics of brown rice flour as influenced by grain activation time and temperatures were investigated. Germination temperatures at 25 ℃, 30 ℃ and 35 ℃ and time for 12, 24, 36 and 48 h significantly influenced the functional properties of flour with modification of starch, protein and high enzymatic activity. Significant decrease in the bulk density, water absorption and swelling power of brown rice flour was observed in comparison to non-germinated flour. Gel consistency and oil absorption capacity of brown rice flour increased as the grain activation time and temperature were increased. Native flour had lowest emulsion and foaming properties, while increase in grain activation time and temperature enhanced the emulsifying and foaming properties of flour. Paste clarity of native flour was 54% which was reduced to 25.17%; however, increase in germination time and temperature increased the % synersis values of germinated flour. Native flour had least gelation concentration of 12% which increased to 25% after 48 h of germination at 35 ℃. Overall, germination can be used as a natural way to modify the functional properties of brown rice flours for their utilization in variety food products.
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