ENZYMATIC MACERATION OF APPLE PARENCHYMA TISSUE. I. MODELLING OF THE KINETICS OF HYDROLYSIS

During the maceration of apple parenchyma with polygalacturonase (PG), three fractions were obtained (residual tissue, free cells or pulp, juice) in which the cell wall material was measured as alcohol-insoluble solids (AIS). A model is proposed to describe the distribution of cell wall material in these three fractions during the course of the enzymatic maceration process, which fitted the experimental data with a determination coefficient r² superior to 0.99. Two processes of maceration were shown to be involved. A first, fast process, degraded a small part of the tissue while the second process slowly degraded the remaining tissue. The maceration products were principally non degradable cells and non degradable soluble pectins. The degradable cells and the degradable pectins accumulated only at the beginning of the maceration. The rate constants followed the Arrhenius law. The initial rate of maceration increased with the amount of PG or the surface area to reach a limit value at high enzyme concentrations or high surface areas, respectively.     

ALPHA-GALACTOSIDASE OF GERMINATING SEEDS OF CASSIA SERICEA SW.

Germinating seeds of Cassia sericea Sw. contain two molecular forms of α-galactosidase which were partially purified and characterized. Both enzyme forms had an optimum pH of 5.0 and an optimum temperature of 50 °C. K_m values for the substrate p-nitrophenyl-α-D-galactoside (PNPG) were 0.91 mM and 1.05 mM for the two forms, and substrate inhibition was observed at high concentrations of PNPG. The two forms of the enzyme had molecular weights of 46,000 and 33,000 by gel filtration. The enzyme forms were inhibited completely by Ag⁺, Cu²⁺ and Hg²⁺ ions and by p-chloromercuribenzoate showing that thiol groups are probably involved in catalysis. Both α-galactosidases hydrolyzed melibiose and raffinose, although hydrolysis of stachyose could not be detected. The enzyme may find potential use in the food industry to hydrolyze flatulence-causing sugars in processed foods and in production of sucrose from high-raffinose sugar beets. That the source (C. sericea seeds) of the enzyme is inexpensive provides an added advantage over use of cultivated legumes as a source of α-galactosidase.     

THE AROMA OF HOPS. II. ON THE COMPOSITION OF HOP OIL

Hop oil was investigated by gas chromatography coupled to a mass spectrometer. Almost all substances were obtained by preparative gas chromatography in amounts sufficient for N.M.R. spectral identification. Hop oil was separated into hydrocarbon- acid- alcohol- and ketone-containing fractions using adsorption chromatography, saponification, alkaline extraction and extraction with Girard T reagent. Fifty-three substances were identified of which sixteen have not been recorded previously as occurring in hop oil.     

THE CHEMISTRY OF HOP CONSTITUENTS. PART XXXV. INTERCONVERSION OF HUMULONE AND ISOHUMULONE

Isohumulone reverts partially to humulone in solution or in sealed tubes under the influence of heat.     

EFFECTS OF LONG-TERM STORAGE OF FOODS ON QUALITY OF PROCESSED FOODS II.

The effects of long-term storage at 4.4, 21.1, and 37.8°C on physicochemical characteristics, nutritional and organoleptic qualities of freeze-dehydrated ration items from Packet Long Range Patrol were studied. The items included beef hash, beef stew, chicken stew, spaghetti with meat sauce, chili con carne with beans, chicken and rice, pork with escalloped potato, and beef and rice. The freeze-dehy drated foods were stable in quality during storage at 4.4, 21.1, and 37.8°C. After 44 months of storage all freeze-dehy drated ration items were in acceptable condition.