Lysozyme (EC 3, 2, 1, 17), which lyses certain bacteria, is an enzyme widely distributed in nature. Its lysing action is based upon the depolymerization of mucopolysaccharides consisting the cell wall of sensitive bacteria. Lysozyme hydrolyzes the β (1→4) linkage between N-acetylmuramic acid and N-acetylglucosamine of mucopolysaccharide. Egg-white lysozyme is a single polypeptide chain containing 129 amino-acid residues, and its tertiary structure has been elucidated.
Lysozyme is produced on an industrial scale from hen's egg-white, and used practically. The most popular application of this enzyme is in clinical uses, which is followed by dietetic application.
Pharmacological actions of lysozyme are reported to be anti-viral action, anti-infectious action, poten-tializing action of antibiotic's activity, normalizing action of intestinal flora, hemostatic action, agglutinating and anti-heparinic action, anti-inflammatory action, regenerative and cicatrizating process favoring action, muco-purulent lytic action, antalgic action and so on. These broad actions result in the therapeutic uses of lysozyme in various fields.
The addition of lysozyme to bovine milk or infant formula, which is presently main dietetic application, is performed as a means of the humanization. The significance of lysozyme in milk is said to lie in the improvement of digestibility of the milk by the formation of softer curd, the normalization of the intestinal flora, and also the participation in the defense mechanism of natural immunity through the enhancement of properdin, γ-globulin and aggulutinins.
The recent applied studies on lysozyme have opened new applications of the enzyme as a preservative for food like sausages, “Kamaboko ”, broiler, raw marine products, saké etc., as well as an antibutyric acid blowing agent in semi-hard cheese production. Lysozyme was found to prevent sake from Hiochi putrefaction.
Attempts to increase yields and purities of products like bacterial catalase, L-asparaginase and glutaminic acid in the industrial fermentation using lysozyme have been made.

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This is a review of the recent chemical studies on the lipids of hen's egg yolk.
(1) The lipids in egg are concentrated in the yolk. One-third of the yolk is lipid, which consists of about two-thirds neutral lipids and one-third polar lipids.
(2) The neutral lipids are composed of sterolester, carotenoid, triglyceride, fatty acid, diglyceride, sterol, monoglyceride and so forth, among which triglyceride is predominantly much. Position 1 of the triglyceride molecules is mostly occupied by palmitic acid (saturated acid), position 2 by oleic and linoleic acids (unsaturated acids) and position 3 by oleic, palmitic and stearic acids (unsaturated and saturated acids), respectively.
(3) The polar lipids involve ceramide, cerebroside, phosphatidylethanolamine, lysophosphatidy lethanolamine, phosphatidylcholine, sphingomyelin, lysophosphatidylcholine and so on. Phosphatidylcholine and phosphatidylethanolamine are in the more amount and sphingolipids are in the less. The fatty acid composition at position 1 and position 2 of the two glycerophospholipids does not resemble to each other, and that of phosphatidylcholine and triglyceride is considerably similar. The fatty acid patterns of sphingolipids are varied to one another, although the fatty base ones are almost the same.
(4) The most of the lipids exists as lipoprotein in the yolk. The low-density lipoprotein is postulated to be an oily globule of mainly triglyceride surrounded by a thin membrane made of protein, polar lipid and probably cholesterol. The high-density lipoprotein is supposed to be a granule of protein and lipid, where a part of the lipid is rather loosely located in the surface of the protein molecule while the most of the lipid is tightly held within the network structure of the protein.
(5) In the chemical studies on the egg yolk lipids, detailed investigations of the individual lipid covering not only the major lipids but the minor lipids and attempts to clarify the existing state of the lipids in the lipoprotein molecule would be among the urgent problems.

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It has been reported that L-lysine added to rice grains removes odor of aged brown rice by reacting with hexanal and other odoring compounds. Since stock of surplus rice carried over from previous crop years obtains peculiar odor that detracts from its eating quality and is becoming a serious problem, experiments were undertaken to fortify rice grains with L-lysine and to simultaneously remove odor and recover the eating quality. From chemical and sensory analysis data, it was demonstrated that 80% of added L-lysine was retained in cooked rice after cooked in an electric rice cooker, and that acceptability of aged rice samples was significantly improved by fortyfication with L-lysine except with high-grade samples.

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It was found that lysine reacts with an acidic ninhydrin-copper reagent to give a characteristic orange color. The reagent and the color are very stable. Moreover, the reaction is very specific for lysine. Other amino acids with the exception of proline and glycine, salts, glucose, urea, ammonia do not give similar color and do not interfere the reaction. Applying this reaction, the authors developed a simple and rapid method for the detection and colorimetric determination of lysine in lysine-enriched foods.
A sample is extracted with hot water. Carbohydrate in the extract is hydrolysed with amylase under suitable conditions to obtain clear solution. After centrifugation, if necessary, the clear super-natant solution is concentrated to 15 to 50mg/dl. Two ml of this solution is mixed with 4ml of the reagent solution (5.0g of ninhydrin and 6.7g of cupric chloride dihydrate are dissolved in 125ml of 0.1M citrate buffer (pH 1.30) and 375ml of methylcellosolve, then diluted with 500ml of water). The mixture is heated in a boiling water bath for 20 minutes and cooled. Then 15ml of water is added to the mixture. The absorbance at 475mμ in a 10-mm cell is read against a reagent blank. Lysine in lysine-enriched bread and other foods were determined by using this procedure. The results were in close agreement with those obtained by a microbioassay or by a conventional colorimetric method with Folin's reagent.

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When amino acid diet containing diammonium citrate alone in place of nonessential amino acid mixture (DAC diet) was singly supplemented with individual nonessential amino acids at the level cor-responding to that of control diet, the growth response, food intake, plasma free amino acid pattern and liver glutamate dehydrogenase activity were examined using Wistar strain male rats.
The proportion of essential and nonessential amino acids in the control diet was patterned according to the mixture shown to meet the requirements for young rats by Rama Rao et al., but each dietary level was restricted to 80% of their original one.
Single addition of glycine, glutamic acid or alanine to the DAC diet produced about the same weight gain as in the control group after 7 days' feeding in experiment 1, but could not prevent initial growth retardation consistently observed in rats fed ammonium salt containing diet. Throughout the similar 3 experiments single addition of glutamic acid or alanine seemed to somewhat improve the weight gain over that of the DAC group.
There was no difference in liver glutamate dehydrogenase activity between the control and DAC groups after 7 days' feeding.
Analyses of plasma free amino acid concentrations showed in general that the plasma alanine, glycine and serine levels were significantly lower in the DAC group than those in the control group. Even when glutamic acid, glycine, serine or alanine was added to the DAC diet, the plasma free serine, glycine and alanine concentrations were markedly reduced regardless of the same dietary level in both diets for a specific nonessential amino acid, except free alanine level in the rats fed glutamic acid. The concentration of the plasma free threonine was consistently lowered by the feeding of the DAC diet with or without added single nonessential amino acid. To the contrary, plasma free lysine level appeared to increase in all groups over the control group.
When the rats which had been on a 60% casein diet for 7 days were changed to the DAC diet, the initial growth retardation seemed to be lessened to some extent.
Nitrogen balance of the DAC group was significantly lowered on day 1 as compared with the control group, but rapidly restored near the control value in only 2 days.

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This experiment was carried out to determine the effects of gamma radiation storage, CA-storage. polyethylene packaging, and cooking on nitrate and nitrite contents of potato tuber.
Nitrate and nitrite contents in potato tubers considerably varied according to the size of the tuber, individual potato plant, and different fields. But nitrate content was almost the same among the potato tubers of similar weight from the same plant. There was found more nitrate content in stem-end of potato tuber than in bud-end. Nitrate and nitrite were stable to heating for cooking, but the losses of nitrate and nitrite were caused by exudation from potato tissue into the cooking water. During the storage in the conditions of low concentration of oxygen that inhibited the respiration of potato tubers, nitrate decreased and nitrite increased slightly. In the gamma-irradiated potato tubers, nitrate increased and nitrite decreased immediately after irradiaton, and both contents of nitrate and nitrite gradually decreased during the subsequent storage.

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Dehydro-L-ascorbic acid (DHA) or 5, 6-diacetyldehydro-L-ascorbic acid (AcDHA) prepared from 5, 6-diacetyl-L-ascorbic acid was heated with glycine in 90% ethanol at 80°C for 30 minutes. The resultingred pigments were separated from a cellulose powder column by eluting with methanol and then precipitated from the methanolic solution, after concentration, with the addition of ether.
DHA-glycine and AcDHA-glycine pigments have three absorption maxima at247, 382 and 520, and 246, 387 and 522 mμ in ethanol, and at 247, 383 and 510, and 245, 385and 510 mμ in water, respectively.
The stability of both pigments in buffer solutions of various pH and in aqueous ethanol was investigated. Both pigments were unstable at pH 2, 10 and 12, and were most stable at pH 6. AcDHA-glycine pigment was more stable than DHA-glycine pigment at pH 4, but was less stable than DHA-glycine pigment at pH 8.
AcDHA-glycine pigment was more stable than DHA-glycine pigment in aqueous ethanol. There were little differences in the stability of AcDHA-glycine pigment according to ethanol concentration, whereas the stability of DHA-glycine pigment increased with the increase of ethanol concentration.

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The nutritional value of the rice protein was compared with that of the wheat protein at three different protein levels by the rat feeding experiment.
The diets were prepared from the protein concentrated rice (26.9-33.6% in protein) treated with α-amylase, the wheat gluten (69.4% in protein), wheat starch, rice powder, and wheat flour etc.
The results obtained were as follows:
1) Protein efficiency ratio (PER) of the rice protein at 11% protein level was 1.67 (mean), while that of the wheat protein was 0.79 (mean). The ratio was the rice protein 100: the wheat protein 47 (100: 79 in literature).
2) Biological value (BV) of the rice protein at 11% protein level was 63.1, while that of the wheat protein was 49.1; in the ratio of each value was 100: 68 (100: 89 in literature).
3) Linear correlations betwen the nitrogen intake and the body weight gain in the both rice and wheat groups were observed. The slope of the regression line in the rice diet and the wheat diet was 10.24g/Ng intake and 6.74g/Ng respectively; in the ratio was 100: 66.
These results indicate that difference between the nutritional value of the rice and wheat proteins are greater than those have been mentioned previously.

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