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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Strategies for raw sheep milk storage in smallholdings: Effect of freezing or long-term refrigerated storage on microbial growth

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Author(s):
Tribst, A. A. L. [1] ; Falcade, I. L. T. P. [1] ; de Oliveira, M. M. [2]
Total Authors: 3
Affiliation:
[1] Univ Estadual Campinas, Ctr Food Studies NEPA, UNICAMP, Albert Einstein 291, BR-13083852 Campinas, SP - Brazil
[2] Fed Ctr Technol Educ Celso Suckow Fonseca CEFET R, Voluntarios Patria 30, BR-27600000 Valenca - Brazil
Total Affiliations: 2
Document type: Journal article
Source: JOURNAL OF DAIRY SCIENCE; v. 102, n. 6, p. 4960-4971, JUN 2019.
Web of Science Citations: 2
Abstract

We assessed the effects of freezing and refrigeration over long periods on the microbiological quality of sheep milk. The raw milk was frozen in 1-L plastic bags or 5-L milk buckets and, after 1 mo, thawed at 7 or 25 degrees C. We evaluated these samples immediately after thawing (d 0) and after 1 d of storage at 7 degrees C. Furthermore, we stored fresh raw milk at 7 degrees C for 10 d in the same packages and in a bulk milk cooler at 4 degrees C (adding 10% of fresh raw milk daily). The total bacterial, total psychrotolerant, and proteolytic psychrotolerant counts were evaluated before and after thawing (for previously frozen milk) and daily (for refrigerated milk). The frozen-thawed milks showed no significant increase in bacterial counts immediately after thawing for all samples (<0.7 log cfu/mL), but only the samples packaged in 1-L bags and thawed at 7 degrees C remained micro-biologically adequate after 1 d of storage. Findings of the refrigerated samples were modeled using a modified Gompertz equation, obtaining a lag phase of around 0.5 (5-L bucket), 2.6 (1-L bag), and 7.0 (bulk milk cooler) d for total bacterial and total psychrotolerant counts. Maximum growth rates (mu(max)) were 1.0 and 1.0 (5-L bucket), 1.2 and 1.3 (1-L bag) and 3.0 and 1.5 (bulk milk cooler) ln(cfu/mL) per day for total bacteria and total psychrotolerant counts, respectively. Compared with total bacteria and total psychrotolerant bacteria, psychrotolerant proteolytic bacteria grew slowly, reaching unacceptable counts only after 9 to 10 d of storage. The studied methods are interesting alternatives for preserving raw sheep milk on smallholdings. (AU)

FAPESP's process: 17/02832-4 - Freezing/ thawing of sheep milk: alterations induced in milk, alternatives for minimize these modifications and impact in the yogurt production
Grantee:Alline Artigiani Lima Tribst
Support Opportunities: Regular Research Grants