NUTRITIVE VALUE OF A FIBER-FREE COCONUT PROTEIN EXTRACT OBTAINED BY AN ENZYMIC-CHEMICAL METHOD

The fiber-free coconut extract obtained by an enzymic-chemical method (J. Food Sci. 38: 607) proved to have a higher protein nutritive value than that of the original coconut meal. The improvement is attributable in part to the fact that the fiber of unmodified coconut meal has an unfavorable effect on the nutritive value of coconut protein. Amino acid analysis revealed that the extracted protein had a higher total essential amino acid content including a higher lysine content and a higher lysineto-arginine ratio than the original coconut meal.     

External Fat Cover Influence on Raw and Cooked Beef 2. Cooking Time, Losses, Press Fluid and Shear Force Values

SUMMARY: The semitendinosus muscle was used in a study of the influence of the external fat cover and the oven temperature on the characteristics of cooked beef. Roasts were cooked either with or without the external fat cover to an internal temperature of 58°C (rare). Two oven temperatures, 163° or 218°C, were used. The roasts cooked at 218°C required a shorter time in the oven than did the roasts cooked at 163°C but the presence or absence of the external fat cover had very little effect on the min per lb. Roasting at an oven temperature of 218°C caused significantly greater total cooking losses than roasting at 163°C. The cooking losses were increased significantly by cooking the roasts with the fat cover on, as compared with removing the external fat The increase was mainly due to an increase in the drip losses. The presence or absence of the external fat cover had a significant influence on the quantity of press fluid obtained from the samples. A greater amount of fluid was pressed from the roasts without the fat cover. The posterior ends of the muscle were more tender (as indicated by Warner Bratzler shear force values) than the anteriomr ends. The lower oven temperature also caused significantly more tender roasts.     

ESTIMATION of HEAT of MOISTURE SORPTION and IMPROVED CRITERIA FOR EVALUATING MOISTURE SORPTION ISOTHERM EQUATIONS FOR FOODS

Heat of sorption of moisture on foods can be estimated from sorption isotherm equations having both moisture and temperature as independent variables. Sorption thermodynamics dictate that the heat of moisture sorption should decrease with increased moisture concentration, or increased temperature of food, provided no biological, chemical or other changes occur during sorption. This fact, and the Clausius-Clapeyron equation were used to derive two analytical formulae to evaluate the reliability of moisture sorption equations in the calculation of heat of sorption. As examples, Chung and Pfost, modified Harkins and Jura, modified Henderson, and Guggenheim-Anderson-De Boer equations at specified conditions were analyzed.     

Differentiation of Australian wine isolates of Oenococcus oeni using random amplified polymorphic DNA (RAPD)

Intraspecific variation of Oenococcus oeni , the preferred lactic acid bacteria species for inducing malolactic fermentation in wine, was studied using the randomly amplified polymorphic DNA (RAPD) strain fingerprinting technique. Ten of fifteen isolates of O. oeni from Australian wineries situated in different wine regions could be distinguished by the RAPD technique. Strains of O. oeni which originated from the same winery were either indistinguishable or closely related to each other. Six different commercially available O. oeni strains could be differentiated with the four RAPD primers used and their genetic similarity determined. Analysis of O. oeni present in wines from a single source of fruit (Cabernet Sauvignon, vintage 2002) that underwent spontaneous malolactic fermentation revealed wide genetic variation amongst the isolates. Each fermentor contained several different O. oeni strains, which were present throughout alcoholic and malolactic fermentation. These data highlight the sensitivity of RAPDs when suitable primers are applied to O. oeni of unknown genetic origin, thus enabling O. oeni strains with desirable sensory and fermentation properties to be genetically analysed.     

BACTERIAL ADHERENCE AND VIABILITY ON CUTTING BOARD SURFACES

The adherence and viability of Escherichia coli inoculated onto the surfaces of plastic cutting boards and new and used wood cutting boards were evaluated. Most of the inoculum was recovered from all surfaces after resident drying times of 5 min and from plastic surfaces at 24 h. When the exposure time was extended to 2 h, > 90% of the cells placed on new and used dry wood surfaces were not recovered after vigorous rinsing. Scanning electron microscopy showed that the bacteria resided within the structural xylem fibers and vegetative elements of the wood. After resident drying times of up to 2 h, almost 75% of the adherent bacteria on the wood surfaces were viable, as defined by a nalidixic acid direct viable count procedure. Microcosm studies showed no intrinsic growth-supporting or toxic properties of the cutting board materials. Bacteria that adhered to plastic surfaces were more easily removed by low-temperature washing than were cells that adhered to wood surfaces. These studies demonstrated that bacteria adhering to wood surfaces resided within the structural and vegetative elements of the wood's xylem tissues and were viable; wood was more retentive than plastic; penetration of the inoculum liquid promoted cell adherence to the wood matrix; and conditioning of wood with water before inoculation interfered with bacterial adherence.     

Computational fluid dynamics studies on pasteurisation of canned milk

Pasteurisation is a vital unit operation to inactivate the spoilage organisms and enzymes present in the milk. Computational fluid dynamics (CFD) modelling can be used as a tool to determine the temperature distribution pattern inside canned milk during thermal processing. In this study, a CFD model was developed for the pasteurisation process of canned milk at 74°C and 85°C and validated with the experimental measurements. Moreover, the effect of can rotation (5, 50 and 100 rpm) on processing time and pasteurisation value was investigated. This study predicted rotation of can with 5 rpm was more effective than stationary positioned can during pasteurisation.     

ETHYLENE CAPSULE PROMOTES EARLY RIPENING OF 'd'ANJOU' PEARS PACKED IN MODIFIED ATMOSPHERE BAGS

‘d'Anjou’ pears (Pyrus communis, L.) harvested commercially with flesh firmness of 64.5 N were incapable of ripening normally at 20C within 60 days of air storage at ‐1C (denoted as “under‐chilled” fruits). When under‐chilled ‘d'Anjou’ fruits (8 fruits, total fruit weight of 1.8 kg) were packed in a 3.8‐liter perforated bag inserted with an ethylene capsule, fruit would ripen normally at 20C. The ethylene concentration in the packed bag maintained no less than 100 ppm after 4 days at 20C, and declined to about 25 ppm on day 7. Regardless of the storage length, ripened fruit induced by the ethylene capsule developed high buttery and juicy texture. If ‘d’ Anjou’ fruit had been stored at ‐1C for less than 30 days, ripened fruit lacked high flavor quality. Flavor quality of ripened fruit improved rapidly when the fruit had been stored for longer than 30 days.     

Effect of a bacteriocin‐producing strain of Lactobacillus paracasei on the nonstarter microflora of Cheddar cheese

In this study, the growth of chloramphenicol‐resistant bacteriocin‐sensitive indicator strain Lactobacillus casei DPC 2048^CM was evaluated in Cheddar cheese made with bacteriocin‐producing Lactobacillus paracasei DPC 4715. No suppression of growth of the indicator strain was observed in the cheese during ripening, and no bacteriocin production by L. paracasei DPC 4715 was detected by the well diffusion method in cheese and cheese extracts. The bacteriocin produced by L. paracasei DPC 4715 was sensitive to chymosin and cathepsin D, and it may have been hydrolysed by the rennet used for cheese manufacture or by indigenous milk proteases.     

Inhibition of rennets by blood serum

Incubation of calf chymosin with the serum from blood of various mammalian species before addition to milk reduced its milk‐clotting activity at 30°C; the inhibitory potency of the sera was in the order horse > goat > cattle > donkey = human. For all species, inhibition of calf chymosin increased on increasing both the incubation time and the level of blood serum. Horse blood serum inhibited other milk coagulants in the order porcine pepsin > Cryphonectria parasitica proteinase = calf chymosin > Rhizomucor miehei proteinase = bovine pepsin. Methylamine‐treated blood serum did not inhibit calf chymosin, suggesting that α₂‐macroglobulin may be the principal inhibitor of rennet in blood serum.     

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女主人SUE,自从上个世纪70年代,就搬进了位这间于美国旧金山市中心的老宅,那时,这个地区的房屋曾被作为廉价之所,租住着大批波希米亚的年轻艺术家以及学生们,但随着岁月变迁,这片区域成为了炙手可热的黄金地段且房价不菲。SUE于近年开始计划整修房屋,没想到丈夫却突然辞世,无