摘要:

Because of the wide range of physiological properties found in the genus Bacillus one of the main problems in the standard procedure for isolating these organisms from milk and dairy products is the difficulty in defining conditions which are suitable for the activation and outgrowth of all spores present. This study investigated the effects of various raw milk heat treatments, the addition of L‐alanine (a nutrient encouraging germination) to the milk after heat treatment, different incubation temperature‐time combinations and two confirmatory media on the recovery of psychrotrophic, mesophilic and thermophilic Bacillus spp occurring in raw bulked milk. There was no significant difference (p>0.05) between the confirmatory media used, ie, starch milk agar and milk plate count agar. However, it was found that heat treatment, addition of L‐alanine and the incubation period had significant effects on the recovery of the organisms from raw milk. The highest numbers of psychrotrophic and mesophilic spores were recovered after a heat treatment of 80d̀C for 10 min followed by the addition of L‐alanine to the milk at 0.1% wlv, and incubating at 6.5°C for 15 days for the former and 30d̀C for 15 days for the latter. The highest numbers of thermophilic spores were recovered from raw milk by a heat treatment of 80d̀C for 30 min, addition of L‐alanine and incubating at 55

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1994.tb01531.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

A study of the hygienic quality of samples of commercial raw milks was carried out using total plate count and a reagent kit for estimating bacterial adenosine triphosphate (ATP) in milk. The method based on ATP is of greater precision. A relationship between the two counting procedures is derived and the statistical properties of computed plate counts from measurement of ATP are discussed.

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1994.tb01532.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The growth rate of the starter culture and its effects on the gelation process of caprine milk were determined. Caprine milk was fermented using various levels of starter culture inoculum and the acidification, growth and gelation profiles were obtained. The caprine yogurt samples inoculated with lower starter culture levels (1% and 1.5% wlv) produced gel structures about eight to 10 times stronger than that made using a 2% v/v inoculum. The gelation patterns suggested that the formation of the gel structure during the caprine yogurt fermentation was time dependent. This behaviour may be due to the presence of higher cell numbers in the caprine yogurt system.

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1994.tb01533.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The effect of pH manipulation prior to high heat treatment on the effectiveness of whey protein denaturation in milk for cheesemaking has been studied. It has been found that the severity of heat treatment of milk required for denaturation can be reduced if the pH is altered during heating. The sensory and functional properties of cheddar‐type cheese produced for high heat treated milk can be improved by manipulation of pH on heat treatment of mil

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1994.tb01534.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Cheese sauces were prepared by blending cheese powders, starches, skim milk powder, flavouring agents, milk and/or water to ˜24% dry matter, cooking to 98°C and simmering for ˜2 minutes. Most sauces exhibited thixotrophic behaviour as characterized by the curvilinear decreases in viscosity and shear stress with time when subjected to a constant shear rate (118s‐1). However, Colflo 67 based sauces underwent shear thinning initially and then shear thickening at shearing times>˜200 s. Increasing the total starch level from 2 to 4% resulted in sauces which had more viscous consistencies, higher susceptibility to shear thinning and higher viscosities on completion of shearing. The rheological properties of sauces were markedly influenced by serving temperature and the type of starch base used. Variation in the level of cheese solids in the cheese powder had little influence on the rheological characteristics of sauces when used at levels of<10%

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1994.tb01535.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1994.tb01536.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Book reviewed in this article:Food Safety 1993. By M E Doyle, C E Steinhart and B A Cochrane. Marcel Dekker, New York. 1993.Flavour Measurement. By Chi‐Tang Ho and Charles Manley. Marcel Dekker, New York. 199

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1994.tb01537.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY