APPLYING PROTEOLYTIC ENZYMES ON SOYBEAN. 6. Deodorization Effect of Aspergillopeptidase A and Debittering Effect of Aspergillus Acid Carboxypeptidase

SUMMARY— A proteolyzate obtained by treating an isolated soybean protein preparation with Molsin, a crude preparation of aspergillopeptidase A (APase A), was less bitter and contained larger amounts of free amino acids, especially hydrophobic amino acids. A proteolyzate obtained by treating this protein preparation with crystallized APase A was much more bitter and contained smailer amounts of free amino acids, mainly consisting of hydrophilic amino acids. The latter was richer in peptides than the former, bearing hydrophobic amino acid residues near the C-termini. Difference in N-terminal amino acid composition apparently has not been found between the 2 proteolyzates. These results indicate that Molsin per se contains a certain carboxypeptidase which decomposes the C-terminal structures and, consequently, lessens the bitterness (debittering effect). This carboxypeptidase was found to be identical with aspergillus acid carboxypeptidase (AACPase). Abase A, as well as MO/sin, was effective in removing odor ants, i.e., n-hexanal, n-hexanol and n-heptanol, from the isolated soybean protein preparation Ideodorization effect). AACPase seemed to have no deodorization effect. A method was suggested to prepare a deodorized and debittered proteolyzate by a combination use of APase A and AACPase.     

PHYTOCYSTATINS AND THEIR TARGET ENZYMES: FROM MOLECULAR BIOLOGY TO PRACTICAL APPLICATION: A REVIEW

Cystatins are protein inhibitors of cysteine proteinases. Oryzacystatin I (OC-I) has been cloned and is apparently the first well-defined cystatin of plant origin (phytocystatin). Besides OC-I, various other phytocystatins occur in rice, corn, wheat and soybean. Phytocystatins have endogenous target enzymes whose expression is induced by gibberellin, and also exogenous target enzymes from viruses and insects. It is thus likely that phytocystatins are involved in the regulation of intracellular protein catabolism as well as in the defense from infection. Better understanding of this phenomenon and cloning of appropriate genes will facilitate the creation of transgenic crops with enhanced resistance to viruses and insects.     

Mechanism of inactivation of heat-tolerant spores of Bacillus stearothermophilus IFO 12550 by Rapid Decompression

The effect of three rapid decompression methods to clear the mechanism of inactivation of heat tolerant spores of Bacillus stearothermophilus IFO 12550 was investigated. Pressurization of the spores at 200 MPa and 75°C for 60 min caused a kill of 10⁴ CFU/mL by the link-motion system but the nonrotational rod valve and E.G. seal methods gave a kill of about 10³ CFU/mL. Sterilization was due to the physical breakdown of spore coat, and was induced by its physical permeability of water at high pressure and temperature. Rapid decompression by the link-motion system at 200 MPa decreased the D-value of the spores from 3000 min (100°C, one atmosphere) to 6 min, 11 min, and 17 min at 95, 85, and 75°C, respectively.     

Quality Improvement and Evaluation of Hypoallergenic Rice Grains

The color of hypoallergenic rice grains, produced by an enzymatic process was improved by treatment with diluted hydrochloric acid and washing with water. The acid-treated grains were steamed at the surface layer to prevent breakage. Textural evaluation showed the cooked hypoallergenic rice grains had a favorable stickiness/hardness ratio.     

Raman Spectroscopy of Heat-Treated B2O3-SiO2 Glasses

Raman spectra were measured on B₂O₃-SiO₂ glasses heat-treated at different temperatures and for different periods of time. It was found that the intensity ratio of the 810- and 475-cm⁻¹ bands depended on the thermal history and composition of glass. The intensity vs heat-treatment temperature curve exhibited a maximum in the glass-transition temperature range. High-temperature Raman spectra were measured on 0.5B₂O₃-0.5SiO₂ glass, both with increasing and decreasing temperature, between room temperature and 600°C. Above 300°C with increasing temperature, the intensity of the 810-cm⁻¹ band decreased, whereas the intensity of the 475-cm⁻¹ band increased. The changes reversed with decreasing temperature. The reversible change of the intensity of the two bands was interpreted as a reversible formation and decomposition of boroxy rings with temperature. The reaction becomes very sluggish below the glass transition so that the intensity ratio stayed constant below 300°C.     

A THEORETICAL STUDY ON ADAPTIVE QUALITY CONTROL SYSTEMS

This paper is a study of an adaptive quality control system from a viewpoint of quality goal. The main purpose is to introduce a conceptual framework for setting up quality goals which are in accordance with the external environment and internal capacity of quality control systems. We apply a mathematical general systems approach.

The results of our paper are summarized as follows:

1)As important decision-making in adaptive QCS, the decision-making for estimalion of fitness and examination of attainability are proposed and formalized mathematically.

2)A refinement process is formalized in which models are revised according to the changes of market.

3)Basic steps for setting quality goals are obtained which are based on the above formalization.     

MODULATING THE CONDITIONING OF MEAT BY THE USE OF ORYZACYSTATIN, A CYSTEINE PROTEINASE INHIBITOR OF RICE SEED ORIGIN

A new process was developed to regulate the papain-induced overtenderization of meat by using oryzacystatin, a cysteine proteinase inhibitor of rice seed origin. Meat cubes (2 × 2 × 2 cm each), aged 3 days, were treated with a 0.1 fold weight of papain solution and incubated at 8°C. The most favorable degree of tenderization resulted when a 2% papain solution was used for 2 h at 8°C. When the incubation was made for 24 h or longer, overtenderization resulted. The incubation of a meat cube with papain for the first 2 h and then with an adequate amount of added oryzacystatin for the subsequent 22 h was effective in regulating overtenderization. It was also confirmed by SDS-polyacrylamide gel electro-phoresis that the use of oryzacystatin under similar incubation conditions regulated the papain-aided hydrolysis of myofibrillar proteins.