摘要:

ABSTRACTSimple ranking and rating procedures for hedonic testing were developed from which signal detection analysis gave simple probability values indicating preference. Data were pooled over judges to give preference scores for specific groups of consumers. Rating was preferable when forced choice was to be avoided; ranking was preferable when response bias was a consideration. The rating procedure was less prone to instructional bias than the 9‐point hedonic scale. Ranking methods were extended to measure‘likelihood to buy', when price was included in the decision, as well as degree of prefere

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07960.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe thermal inactivation kinetics of three food‐borne yeasts from heat‐treated products‐twoSacc. cerevisiaeand oneZygosacc. rouxii‐hsve been determined. Thermal treatment and evaluation of results were carried out according to the dynamic heat destruction method. Results for 0.5% (w/w) glucose as heating medium expressed in D55values were 1.05, 2.67 and 0.16 min, respectively. The respective z values were 4.00, 6.23 and 5.55°C. The apparent activation energy for heat destruction calculated from the Arrhenius plot for the three yeasts were 5.05*105, 3.61*105and 3.60*105Jmol‐1. Applying Eyring's theory of absolute reaction rates for thermal destruction, values for enthalpy and entropy of activation could be

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07961.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTListeria monocytogenesstrain Scott A in Tryptose Broth was treated with 100‐300 ppm butylated hydroxyanisole (BHA), 300‐700 ppm butylated hydroxytoluene (BHT) and 10‐30 ppm tertiary butylhydroquinone (TBHQ). Resulting growth curves were fitted using the logistic model, and growth parameters [lag period (LP), generation time (GT), and maximum growth (MG)] were calculated. BHA and BHT inhibitedListeria monocytogenesby increasing LP and GT and decreasing MG. Extent of inhibition was concentration‐dependent for cultures with BHA, but not with BHT. TBHQ at 10‐30 ppm increased LP but did not affect other parameters. LP increased exponentially with increased BHA or TBHQ inListeriaculture. Concentrations of additive required to increase LP by one order of magnitude were 240 ppm for BHA and 26 ppm

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07962.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe effect of aspartame on the early stage of ascorbic acid oxidation in solutions was studied by measuring ascorbic acid retention in an open system at 30°C and the oxygen uptake in a closed system at 33°C. Comparisons were also made between aspartame (0.06% and 0.12%) and sucrose (10% and 20%) in Cu‐catalyzed and noncatalyzed solutions at 30°C. Copper activity in aspartame solution was measured by using a cupric ion selective electrode. Aspartame increased the rate of ascorbic acid oxidation in all tested solutions. In the presence of copper the oxidation rate of ascorbic acid was significantly higher in aspartame solutions than in sucrose solutions despite the fact that aspartame showed Cu‐complex capacity in so

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07963.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTKinetics of aspartame degradation in low to intermediate moisture systems were evaluated by incorporating aspartame into agar/micro‐crystalline cellulose model systems. They were prepared at pH 3, 5, and 7, equilibrated after freeze‐drying to three water activities (0.34, 0.56, and 0.66), and stored at 25 to 45°C. Aspartame in such systems was most stable at pH 5 and became less stable as pH decreased or increased. As the molar buffer salt concentration increased, the rate of aspartame degradation increased. The activation energy ranged from 23 to 36 kcal/

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07964.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThree commercial yogurt cultures and strains ofLactobacillus bulgaricusandStreptococcus thermophilusisolated therefrom were evaluated for their effect on aspartame degradation during and after fermentation. The rate of aspartame loss was related to growth of the organisms. Differences in losses due to strain type did not appear signficiant. Aspartame degradation rates were correlated to metabolic rate of the culture. As the rate decreased, loss of aspartame decreased. As a result, less than 10% aspartame was degraded during 6 wk refrigerated storage. Results indicate aspartame should remain stable in yogurt, provided it is added after fermentation.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07965.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTDrainage of 14 protein‐stabilized foams was determined as a function of time. Drainage conformed to the empirical equation v = Vt/(B + t), where v is the volume of drained liquid at time t, V is the maximum drained volume, and B is the time needed to drain V/2. Rate constants and initial rates of drainage could be calculated from parameters V and B. However, B would be the preferred index of foam stability as it was not influenced by the initial volume of liquid in the foa

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07966.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTEffects of residual air were evaluated on the heating rates of a convectionheating product processed in a continuous rotary sterilizer. Heat penetration tests were conducted in a Steritort at various reel speeds (1‐10 rpm) and air overpressures (0‐69.0 kPa) using 211 × 300, 300 × 407 and 603 × 700 cans containing Washington white beans in brine. Sterilization times calculated by Ball's formula method were longer for test cans processed with overpressure than those processed with no overpressure. Maximum reduction in calculated lethality for 69.0 kPa air overpressure was 15.2% for 211 × 300 and 300 × 407 experiments and 49.4% for 603 × 700 experiments. For each can size and reel speed, average process time was a linear function of ove

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07967.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTNaringin and limonin are two bitter components of some citrus products such as grapefruit juice. Naringin could be removed by hydrolysis with immobilized naringinase and limonin might be removed by adsorption with cellulose monoacetate gel beads. Cellulose triacetate fibers show a similar limonin adsorption capacity as cellulose monoacetate gel beads. Thus when naringinase fromPenicillium sp.was entrapped in such fibers, an enzyme column was made which could remove both bitter components simultaneously. When grapefruit juice was debittered with this enzyme column, sugar components, total organic acids and turbidity were not affected. The enzyme column could be regenerated by washing with warm water. In addition, operational stability of the enzyme column was satisfactory. Such enzyme column could be considered for industrial use.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07968.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe ability of low density polyethylene (LDPE) to absorb citrus flavor compounds was examined. The LDPE sample was mounted on an oxygen electrode. As volatiles were absorbed, oxygen permeation through the polymer increased. Limonene, ethyl butyrate, myrcene, and α‐pinene were readily absorbed by LDPE. Octanal, citral, linalool, and α‐terpineol were absorbed at much lower levels. Time‐course changes in readings were used to calculate diffusion coefficients of volatiles in the polymer. Diffusion coefficients were proportional to the volatile's solubility in the

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb07969.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY