摘要:

The acceptance of dairy products by consumers is generally determined by the product's sensory characteristics. These characteristics are a result of various changes in the product and the surrounding environment. The purpose of this paper is to report on a detailed sensory and consumer investigation of the changes in liquid skimmed milk held over an eight day period at three different storage temperatures: 1°C, 5°C and 10°C. Results of an objective sensory profile and subsequent data analysis revealed that sensory changes in milk could be described and quantified, clearly indicating the product's shelf‐life profile. Product acceptability as perceived by consumers was undertaken on a subset of samples, illustrating the points at which consumers noticed significant changes. Overall, as the samples went through their shelf‐life at the higher temperature they became less acceptable. The final part of the experiment used statistical modelling procedures to interpret and understand the data. As expected, it was shown that products became more stale during storage, and that temperature of storage affected the rate of staling, this being most marked at the higher temperature. Staleness was related to the attributes vegetable, sour, cardboard, chalky and mouthc

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1995.tb02428.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A study of the effect of pasteurization on goats' milk took place in order to compare the effectiveness of two pasteurization processes (low and high pasteurization) by assessing the procedure microbiologically and biochemically. The results revealed that both pasteurization processes were effective, showing microbial destruction of approximately 100%. With regard to the determination of phosphatase activity to monitor pasteurization, data in both cases were higher than the limit established for a well pasteurized milk, according to the method used. Machine milked milk showing a lower microbial content nearly achieved the standard level by batch pasteurization, 0.75 μg phenol/ml, but 2.5 μg phenol/ml by the high temperature short time (HTST) method. Phosphatase activity levels of 1.8 and 4.3 μg phenol/ml were the mean values obtained for low and high pasteurization respectively. Our results lead to the conclusion that the batch method for pasteurization of goats' milk is more efficient in terms of total bacterial count than the HTST method. Furthermore, the technique used for the determination of phosphatase activity does not seem to be adequate for pasteurization control of goats' milk, since in very rare situations were we able to attain the limit establish

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1995.tb02429.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1995.tb02430.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A pilot study was carried out to assist management in the development of an improved strategy for net quantity control in a medium volume, liquid milk, carton line operation. A low cost statistical quality control system was used to demonstrate that computerization for net quantity data handling and interpretation must be part of an improved strategy to prove compliance with weights and measures legislation. A process capability study identified differential behaviour between filling valve sets which required an improved maintenance plan in order to prevent process instability when filling one litre cartons. Preliminary and ongoing process capability indices for skimmed, semi‐skimmed and whole milk in half pint and one pint cartons were two to four times the minimum required to prove capability. Overfill was typically of the order 0.2 to 0.4% of the nominal quantity for half pint and one pint fills, but it tended to be higher for whole milk due to an overestimation of the milk density. Overfill on the one litre carton was shown to be excessive at 0.8% of the nominal quantit

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1995.tb02431.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Flux rate performance for both rennet and cheddar wheys were similar to those described for acid casein whey beginning at 37–41 l m‐2h‐1and declining to 10 l m‐2h‐lat volume concentration ratio of 4. The chloride in dry matter reduction for these wheys was much greater at 71% compared to ∼41% for acid casein whey. Losses of organic solids from acid casein whey in terms of chemical oxygen demand were similar to those published for cellulose acetate membranes. Lactose and true protein nitrogen (total protein nitrogen less non‐protein nitrogen; NPN) losses amounted to 2.6% and 8.1% respectively. NPN constituted the main nitrogen loss (77%) through the HC‐50 membrane. True protein loss increased as pH was lowered to 3.6. Solubility index values obtained for nanofiltered powders produced from acid casein whey were comparable with those obtained for conventional spray dried powders and whey protein concentrates. In a case study based on the performance of the HC‐50 membrane the economic feasibility of nanofiltration along with other demineralization proce

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1995.tb02432.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Raw milks from farm bulk tanks in England and Wales were sampled over a 15 month period in 1992–93 and analysed for Salmonella spp, Listeria spp and Listeria monocytogenes. Of 1673 samples tested for Salmonella spp, six (0.36%) yielded a positive result. A total of 2009 samples were analysed for Listeria spp. Of these, 310 (15.43%) were found positive for Listeria spp, 102 (5.08%) of the positive samples yielded L monocytogenes, which represented 33% of the Listeria isolations. There was a significant rise in the isolation rate for listerias between October and March broadly in line with the period during which the cows were housed indoors. The highest isolation rate was in January, 25.89% in 1992 and 28.4% in 1993, and the lowest isolation rate (3.1%) in August. Although the incidence of L monocytogenes broadly paralleled the trend for total Listeria, the highest percentage of L monocytogenes to total Listeria was found in the months of April to September when the total Listeria isolations were at a minimum. Thirty two (1.59%) samples were found to be positive for Listeria spp prior to enrichment procedure, with 17 (0.85%) positive for L monocytogenes. The highest counts reported for L monocytogenes were 62 and 30 colony forming units (cfu)/ml with over 60% at a level of less than 10 cfu/ml. Of the direct isolations, some 78% were obtained between the months of March and Jul

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1995.tb02433.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY