Lipoxygenase inactivated and sterilised legumes and cereal products
The Lipoxygenase (LOX) enzyme is found in a variety of plant products particularly legumes, such as soybeans, mung beans, navy beans, green beans, peas, and peanuts, and also cereals, such as rye, wheat, oat, barley, com and rice bran. It causes off¬flavour and off-odour in foods. As a food grade product, the beans and bran should be of good keeping quality and high industrial value, in which all the components that may cause deterioration, must be removed or their activity arrested. Important in this respect is that inactivation of lipase and LOX enzymes must be complete and irreversible. At the same time, the valuable nutrients must be preserved. In addition to LOX, some legumes and cereal products, especially rice bran, endogenously contain the lipase enzyme which hydrolyses the primary lipids triglycerides (TG). The resulting fatty acids increase bran acidity and reduce pH, as a result of which off- flavour and soapy taste are produced, and the functional properties change. Most of the thermal and chemical methods are used which are inadequate and unsatisfactory or impractical. The existing technologies like wet milling, pre-soaking in hot water with NaHC03, high hydrostatic pressure (lOO-200MPa), Ultra High Temperature (at 140°C), Microwave-heating etc. that are used to inactivate LOX and trypsin inhibitor in beans and brans have disadvantages like severe processing conditions damaging valuable components of bran, (2) substantial moisture removal, and (3) incomplete and reversible enzyme inactivation (the enzyme resumes its activity on contact with air). Thus in the invention the initial preheat temperature, pressurisation levels, pressurisation time periods, pause time (the time for which the steriliser is in the pressurized or depressurized condition) between pressurization and depressurization and the sequences of pressurisation¬ depressurisation, are judiciously selected to yield a product with inactivated enzyme and which is sterilized, while substantially preserving the nutritional value, colour, texture with enhanced shelf life (including enhanced storage without refrigeration).
Thus in accordance with this invention the said product has the following characteristic features:
1) Legumes and Cereal products with inactivated enzymes (lipoxygenase, trypsin inhibitor and lipase).
2) Lipoxygenase and trypsin inhibitor is completely inactivated.
3) The treated products show no further enzyme activity.
4) Up to 80% of initial Lipoxygenase is deactivated in the final product.
5) It is devoid of any off-flavours.
6) It has a pleasant sweetish taste with a smooth mouth feel as assessed by trained panel.
7) The product is sterilized.
8) It is auto-dehulled.
9) The product is tenderized.
10) The product can be used as a ready-to-use stock for preparing other items (e.g. the treated soybeans can be used to get soy flour, soymilk, tofu etc.)
11) The product can also be consumed directly and also safe for growing children.
12) The oil extraction efficiency in the treated product increases, giving better
13) The product shelflife is 30-45days.
14) The product itself or the other food items prepared from it are shelf-stable without refrigeration