Blend proteinase

Dolch and Tscharntke (2000) studied the effects of artificial defoliation of alder trees on subsequent herbivory by alder leaf beetle (Agelastica alni). After defoliation, herbivory by A. alni was significantly lower in the defoliated trees and its neighbors compared with trees distant from the manipulated trees. Laboratory studies confirmed that resistance was induced not only in defoliated alders but also in their undamaged neighbors (Dolch and Tscharntke, 2000). Follow-up work showed that alder leaves respond to herbivory by A. alni with the release of ethylene and of a blend of volatile mono-, sesqui-, and homoterpenes. This herbivory also increased the activity of oxidative enzymes and proteinase inhibitors (Tscharntke et al., 2001). 

PCPs but increases the propensity to nonenzymatic browning on storage higher levels (>7%) promote textural defects such as crumbliness (Thomas, 1969, 1970 Kairyukshtene and Zakharova, 1982). However, high levels (7-10%) may be added if the skim-milk powder is first reconstituted and then precipitated by proteinases or citric acid and the curd then added to the blend (Thomas, 1977). 

Tsuji et al. investigated the effects of molar mass, l-LA content and average l-LA and d-LA sequence length on the enzymatic degradation of various PLLA/PDLA blends in the presence of proteinase K. The authors observed that enzymatic hydrolysis of PLLA proceeds via both endo and exo chain scission. Non-blended PLA films are enzymatically hydrolyzable when l-LA content and l-LA sequence length are higher than 0.3 and 3, respectively, and d-LA sequence length is lower than 10. 

PLA blends with proteinase K is considerably slower than the neat PLA [89, 91]. 

In this chapter, we review the enzymatic degradation mechanisms of PLA prepared from melt-crystallized, solvent-cast, and blend films, mainly by using proteinase K enzyme molecules. The degradation mechanisms of thin films with thickness of about lOOnm and solution-grown lamellar crystals are also discussed. 

Fig. 17. ESEM micrographs of the surface of a PLAioo7PCL(25/75) blend film after 72 hours degradation in the presence of Proteinase K (a) and in the presence of pseudomonas lipase (b) (Source. from Ref. 41)...

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