Amylases are enzymes which hydrolyze the starch molecules into polymers composed of glucose units. α-Amylases are ubiquitous in distribution, with plants, bacteria and fungi being the predominant sources. Most of the microbial α-amylases belong to the family 13 glycosyl hydrolases, and they share several common properties. But different reaction specificities have been observed across the family members. Structurally α-amylases possess (β/α) 8 or TIM barrel structures and are responsible for hydrolysis or formation of glycosidic bonds in the α-conformation. Stability of the α-amylases has been widely studied; pH and temperature have very important roles to play. Engineering the enzymes for improved stability enhances their use industrially. This review focuses on the distribution, structuralfunctional aspects and factors for enhancing the stability of α-amylases.

The present study pertains to the effect of nutritional factors on the growth and production of antimicrobial substances (AS) by Streptococcus lactis subsp. diacetylactis S1-67/C. Among nine media tested, yeast extract dextrose broth supported good growth and maximum production of AS. Addition of beef extract and yeast extract at 1.0 and 0.6% levels, respectively, increased growth as well as production of AS. Of ten carbohydrates examined, maximum production of AS was achieved with 1% glucose followed by fructose, 4% molasses, lactose, sucrose, galactose, mannitol, maltose and 2% molasses. Xylose inhibited production of AS, although it stimulated growth of the organism. Peptone, tryptone and tryptose (each at the 1.5% level) significantly stimulated production of AS. Other nitrogen sources, including soytone, casein hydrolysate and proteose peptone, retarded production of inhibitory substances. Among the amino acids, L-leucine, DL-methionine and L-glutamic acid were most essential for growth and production of AS, whereas L-lysine, L-proline, DL-serine, DL-asparatic acid, L-arginine-HCl and DL-tryptophan were stimulatory. Other amino acids such as DL-ornithine, L-cysteine-HCl and DL-citrulline slightly stimulated AS production. In the presence of cynocobalmin, niacin, folic acid, calcium pantothenate and riboflavin, S. lactis subsp. diacetylactis S1-67/C produced maximum amounts of inhibitory substances. Omission of individual mineral salts from the basal medium did not affect production of AS by the organism.

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One way to prevent protein-energy malnutrition is to provide nutritious weaning foods to infants. In India, several commercial mixes are available, but they are often too expensive for persons of low socioeconomic status. To find a more affordable product, four weaning mixes were formulated using local foods and traditional processing techniques. They were evaluated for acceptability by a sample target population of mothers and infants, and for protein, iron, and energy content using established laboratory methods. All the mixes were inexpensive and nutritious, and remained acceptable even after being stored for one month.

Availability of iron from sixteen varieties of selected nuts and oilseeds was assessed by in vitro method. Wide and significant variations were recorded in the contents of total and ionisable iron and in the bioavailability of iron of the nuts and oilseeds. The total iron content was the highest in nigre seeds and the lowest in linseed seeds. Bioavailability of iron was significantly high from pistachio nut and almond and markedly low from groundnut. Most of the nuts and oilseeds were found to have less than 10 percent of bioavailability of iron, hence, they were not considered as good sources of iron among plant foods.