Calidad De Leche Toxicologia.

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International Dairy Journal 18 (2008) 109–113 www.elsevier.com/locate/idairyj

The influence of storage on the farm and in dairy silos on milk quality for cheese production
Gabriel Leitnera, Nissim Silanikoveb, Shamay Jacobic, Limor Weisblita, Solange Bernsteind, Uzi Merind,Ã
b a Kimron Veterinary Institute, Bet Dagan 50250, Israel Department of Animal Physiology, TheVolcani Center, Bet Dagan 50250, Israel c The Volcani Center, Bet Dagan 50250, Israel d Department of Food Science, The Volcani Center, Bet Dagan 50250, Israel

Received 19 March 2007; accepted 7 September 2007

Abstract Refrigerated storage of good-quality milk from a single cow resulted in moderate deterioration of its quality, low level of bacterial growth (standard plate and psychrotrophcounts), and low small losses of curd yield. When milk was collected from farm bulk milk tanks and from dairy silos, its quality deteriorated faster than that of single-cow milk, resulting in high bacteria counts and high loss of curd yield, most of which was already apparent for the farm bulk milk tank. Statistical analyses did not reveal any significant interaction between bacterial growth, milkcomposition, somatic cell count, and curd yield loss, indicating that other mechanisms such as enzymatic activity might be responsible. From the comparison between the high-quality milk from an uninfected cow’s udder and the commingled milk on the farm and in the dairy silos, it appears that introduction of milk coming from infected udders might cause curd yield loss such as that noted in the presentstudy. r 2007 Elsevier Ltd. All rights reserved.
Keywords: Milk storage; Milk quality; Curd yield

1. Introduction Milk storage time comprises two distinct periods: in the farm bulk milk tank (BMT) and in the dairy silo. While milking practices and herd management are in the sole hands of the farmer, the storage times of milk in the BMT and in the silos are usually determined by the dairies.There is common agreement that milk quality deteriorates over time, and that holding the milk for a long time impairs its quality, mainly with respect to microbiological standards, but also with regard to other quality aspects, such as curd yield and suitability for manufacturing various dairy products (Barbano, Ma, & Santos, 2006; Barbano,

ÃCorresponding author. Tel.: +972 3 968 3422; fax: +972 3960 5724.

E-mail address: uzmerin@agri.gov.il (U. Merin). 0958-6946/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.idairyj.2007.09.001

Rasmussen, & Lynch, 1991; Mara, Roupie, Duffy, & Kelly, 1998; Roupas, 2001). In bulk milk with high bacterial counts and high somatic cell count (SCC) the impairment of product quality is intensified (Barbano et al., 2006) andcurd yield is lowered (Auldist & Hubble, 1998; Celestino, Iyer, & Roginski, 1996; Leitner, Krifucks, Merin, Lavi, & Silanikove, 2006; Marino, Considine, Sevi, McSweeney, & Kelly, 2005; Roupas, 2001). Despite all the above considerations, very little research has addressed the changes in milk quality between its production on the farm and its processing in the dairy. In the present study the raw milkquality (SCC and bacteria counts) and its suitability for manufacturing cheese were studied in relation to three periods: storage of the milk from individual cow for a period similar to the storage period in the BMT; the storage period in the BMT; and the storage period in the dairy silo.

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110 G. Leitner et al. / International Dairy Journal 18 (2008) 109–113

2. Materialsand methods 2.1. Study design An Israeli-Holstein cow with SCC below 25 Â 103 cells mLÀ1 and a gland free of bacteria as tested for three consecutive times according to accepted standards (Oliver, Gonzalez, Hogan, Jayarao, & Owens, 2004) was used to study the effects of storage on the highest quality milk that could be obtained. The cow was milked in the morning, into an individual sterile...