Changes during CA (controlled-atmosphere) storage of excised shoots of asparagus (Asparagus officinalis L) were studied. Storage in 5% CO,, at 35°F and 95% relative humidity resulted in increased pH, decreased total acidity and total solids, and an increase in soluble solids. There was also more retention of chlorophylls in the CA-stored asparagus. These effects became more pronounced as the concentration of CO, in the atmosphere was increased. The degradation products of chlorophylls in the CA-stored samples ware exclusively the pheophytins. Correlations between changes in pH and the degradation of chlorophylls ware made.

No abstract

SummaryCollagen was used as carrier for the immobilization of invertase, lysozyme, urease, glucose oxidase, penicillin amidase, and glucose isomerase. Immobilization was accomplished by either impregnation of a preswollen collagen membrane with enzyme solution or electrocodeposition of collagen and enzyme from a collagen dispersion containing dissolved enzyme. The collagen-enzyme complexes prepared are in membrane form.Membranous collagen-enzyme complexes were used to construct biocatalytic reactors such as the capillaric coil modular reactor. Such biocatalytic reactors were used in a recirculation system for the conversion of substrates. The biocatalytic reactors showed initial decreases of activity to stable limits which are maintained over a large number of reactor volume replacements. The stable limits correspond to approximately 3575 of the initial activities for Iysozyme and invertase, 257, for urease, and 15% for glucose oxidase.The mechanism of complex formation between collagen and enzyme involves multiple salt linkages, hydrogen bonds, and van der Waals interactions. This protein-protein interaction which leads to stable complexes by both impregnation and electrocodeposition processes is unique among the enzyme immobilization methods currently available.

No abstract

No abstract