Detection of Phenylalanine Ammonia-Lyase in the Skin of Blueberry and Cranberry Fruits

Phenylalanine ammonia-lyase (PAL) was extracted from the skin of individual berries and assayed spectrophotometrically under conditions minimizing interference from co-extracted constituents. Analyses for total anthocyanin (TAcy), soluble solids (SS), and titratable acidity (A) were performed on the same berries. In blueberry fruits, PAL activity was present at all maturity levels examined. Cultivar differences in anthocyanin accumulation were unrelated to PAL activity. PAL activity in cranberry fruit was unrelated to harvest date, cultivar differences in anthocyanin accumulation, or values of TAcy and SS/A in individual berries. Activity was retained in cranberries during 4 wk of refrigerated storage.     

CYSTINE LYASES IN PLANTS: A COMPREHENSIVE REVIEW

Cystine lyases cleave L-cystine through aβ-elimination reaction producing thiocysteine (cysteine persulfide), pyruvate and ammonia. They are responsible for the initial reaction that produces characteristic flavors and aromas in important vegetables of the genus Brassica. In this review, an overview of these plant C-S lyases, comparison with alliin lyases andβ-cystathionases, purification protocols, substrate specificity, function and biochemical characteristics will be discussed. The importance of these enzymes to food science will also be examined.     

AQUEOUS GARLIC EXTRACT AND MICROBIOLOGICAL QUALITY OF REFRIGERATED POULTRY MEAT

The antibacterial effect of garlic extract (5, 10 and 15%) was investigated on poultry carcasses obtained from a slaughterhouse, stored under refrigeration, and evaluated at selected time intervals. The effect of the garlic extract on the microbial contaminants of the poultry carcass surface – Salmonella, strict and facultative aerobic, mesophilic, and total and fecal coliforms – was evaluated. The garlic extract exhibited a concentration‐dependent reduction of microbial contamination. Garlic extract concentrations of 10 and 15% were the most effective. The bacteriostatic action of garlic extract against mesophilic microbiota can be observed until the third storage day. The count of total and fecal coliforms remained low during the storage period. Chicken feed was the apparent source of Salmonella contamination, and the aqueous garlic extract was not effective against Salmonella.     

Role of Acetaldehyde Production in the Removal of Astringency from Persimmon Fruits under Various Modified Atmospheres

Astringency of persimmons was removed by enclosing the fruits in polyethylene bags under vacuum or by replacing air with N₂ or CO₂. Acetaldehyde produced by the fruit under these conditions accumulated at different rates. The rate of the deastringency process was directly proportional to the level of acetaldehyde accumulation. Thus, the fruit held at 20°C in CO₂ was the first to lose its astringency, but showed internal browning after 1 wk. Fruits under vacuum or N₂, where less volatiles accumulated, maintained their high quality and firmness for 2 wk at 20°C or 3 months at ? 1°C. However, fruit held under vacuum began to show internal browning when acetaldehyde accumulated above a certain level.     

Microbiological and physicochemical characteristics and aminopeptidase activities during ripening of Serrano cheese

The physicochemical and microbiological characteristics and the aminopeptidase activity variation of Serrano cheese during winter and summer were investigated. Samples from different producers varied significantly, showing nonstandardized procedures for the manufacturing and ripening of this product. There were no significant changes in aminopeptidase activity during maturation and most of the enzyme activity found in the water extracts of cheese would have their origin in lactobacillus and enterococci, suggesting autolysis of these micro-organisms. Results show an increase in free amino acids during maturation, with higher amounts in the summer product.     

Optimizing the Enzymatic Maceration of Foliole Purée from Hard Pieces of Hearts of Palm (Euterpe edulis Mart.) using Response Surface Analysis

Response surface analysis was applied to investigate modifications in viscosity of foliole purée treated with commercial enzyme preparations high in cellulase and endopolygalacturonase (pectinase) with changes in enzyme concentration (0.3–1.2%), incubation time (3.3–6.7 hr) and temperature (40–50°C). Foliole purée was obtained by trituration of hard pieces of hearts of palm (Euterpe edulis) and incubated in a rotating agitator. After treatment with 0.81% cellulase for ～5 hr at 50°C, a fourfold reduction in viscosity was found relative to a control sample. The minimum viscosity for this treatment was within the experimental range investigated. Optimized experimental conditions for treatment with pectinase however were outside the experimental range. The application of the cellulase preparation to the purée resulted in a 10% increase in yield of edible palm.     

ANTIBIOTIC RESISTANCE OF CAMPYLOLOBACTER ISOLATED FROM AUTOMATED BROILER FARMS

The use of the same antibiotics in animal food and conventional medicine can cause problems in the treatment of human diseases, because poultry frequently carry human pathogens. The aim of the present study was to determine the antibiotic resistances patterns of Campylobacter jejuni isolated from the rearing environment of broiler chickens – litter, drinking water, feed and the bird's cloaca. The results showed significant resistance to the following antibiotics: sulfonamide (77%), tetracycline (100%), erythromycin (80%) and penicillin G (100%). Intermediary resistance was present in bacitracin (90%), trimethoprim (100%), vancomycin (100%), chloramphenicol (97%), nalidixic acid (100%) and azithromycin (100%). However, new studies need to be carried out in Brazil to determine the resistance amplitude of this microorganism in other animals and humans. It is important to define some control strategies of the antibiotics used in animal production and human medicine.     

Involvement of Acetaldehyde and Ethanol Accumulation During Induced Deastringency of Persimmon Fruits

Application for 48 hr of CO₂ or N₂, or mixtures of both, to astringent persimmon fruits, was found to be efficient in removal of astringency. Anaerobic conditions induced stimulated production of acetaldehyde and ethanol by the fruits. Ethanol production was unaffected by the different gas compositions. However, the highest level of acetaldehyde was found with the highest CO₂ concentration. The lowest acetaldehyde levels were measured in fruits treated with N₂ only. The rate of the deastringency process was positively correlated to the endogenous level of acetaldehyde attained in the fruit. However, the high acetaldehyde levels produced during CO₂ treatment of 72–96 hours evidently caused injury to the fruit pulp.