SUMMARY Beef round muscle was separated according to solubility characteristics into water soluble, salt soluble and insoluble fractions. These showed different degrees of hydrolysis when reacted with an enzyme. The magnitude varied with nature of the enzyme. Collagenase, bromelain and trypsin showed stronger solubilizing activity on the insoluble fraction than on the salt soluble fraction; whereas papain, Rhozyme P‐11 and ficin showed strong activity on the salt soluble fraction and hydrolyzed the insoluble fraction less efficiently. In general, the water soluble fraction was more resistant to enzyme hydrolysis than the other fractions, except with papain and Rhozyme P‐11. However, the portion of the water soluble fraction, that was hydrolyzed appeared as smaller peptides than the solubilized fregments of the other two fractions.

S Tenderization of meat by papaya latex preparations was achieved by the combined action of several proteases. Both in vitro and in vivo application of enzymes gave degradation of muscle proteins, and degradation of connective tissue only after heat denaturation. Purified papaya enzymes‐papain, chymopapain and papaya peptidase A‐were uniformly distributed throughout the various muscles and in the extravascular system after antemortem injection into the vascular system. Chymopapain was the primary contributor for tenderization because it constituted the major protease in the mixture and it had higher thermostability and more favorable action at the meat's natural pH than papain or papaya peptidase A.

Requirements in terms of water activity (a,) for the growth, sporulation, and germination of Clostridium perfringens were determined. Strain A48 was used in all phases, and in addition either NCTC 8239 or NCTC 8797 was used for growth, sporulation, and germination studies. The desired a, of the test media was obtained by the addition of one of three solutes: glycerol, sucrose, or sodium chloride. The freezing point depression method was used to determine the a,. The basal medium for growth and germination was Fluid Thioglycollate Medium. It had an a, of 0.995 and produced maximum growth and fastest growth rate among the six levels of a, tested. The lowest a, supporting growth and germination of C. perfringens was between 0.97 and 0.95 in the test media made with sucrose or sodium chloride and 0.93 or below in the test media adjusted with glycerol. Spore production by C. perfringens in Ellner's or modified medium required a higher a, than growth. An understanding of the influence of the available water in foods on the growth, sporulation, and germination of Clostridium perfringens may aid in control of this microorganism as a cause of foodborne illness. The available water activity (a,) in a food is affected by all of the constituents which have an affinity for water. These will include those which can be metabolized by the organism as well as those which cannot. In addition, food processing may alter the available water. Gough and Alford (5) tested the effects of NaCl, NaNO3, and NaNO2 on growth, survival, and heat resistance of several strains of C. perfringens. Growth occurred in concentrations of these salts which were higher than those used in the normal curing of meat. A NaCl concentration of 6% (w/v) in Fluid Thioglycollate Medium was required to inhibit growth significantly. The

Requirements in terms of water activity (a w ) for the growth, sporulation, and germination of Clostridium perfringens were determined. Strain A48 was used in all phases, and in addition either NCTC 8239 or NCTC 8797 was used for growth, sporulation, and germination studies. The desired a w of the test media was obtained by the addition of one of three solutes: glycerol, sucrose, or sodium chloride. The freezing point depression method was used to determine the a w . The basal medium for growth and germination was Fluid Thioglycollate Medium. It had an a w of 0.995 and produced maximum growth and fastest growth rate among the six levels of a w tested. The lowest a w supporting growth and germination of C. perfringens was between 0.97 and 0.95 in the test media made with sucrose or sodium chloride and 0.93 or below in the test media adjusted with glycerol. Spore production by C. perfringens in Ellner's or modified medium required a higher a w than growth.

Measurement of protease activity A method has been dareloped for the part@ purification of a c&l-cium activated neutral protease from bovine muscle, since application of methods previously used for rabbit or porcine muscle gave little or no yield. The new method involves extraction with phosphate-buffered KCl, saling out with (NH&SO4, affinity chromatography on mercurial agarose followed by gel filtration. The bovine protease required :alcium ion and reducing agent for activity with a pH optimum at 7.5 and hydrolyzed myofibrillar proteins.Casein digestion was determined using 0.2-l mg enzyme per ml at 25'C by the method described by Kang and Warner (1974)