Abstract
The aim of this study was to analyze the influence of milk collection frequency (24 h versus 48 h) and milking dayshift (morning and evening) on total mesophilic aerobic bacteria (MAB) and psychrotrophic bacteria (PSY) counts in raw milk samples. MAB counts were determined by flow cytometry (BactoScan) and PSY counts by the plate counting agar method. An univariate statistical analysis was performed to find out significant differences among the studied factors. Results obtained showed that collecting milk every 24 h was effective in reducing MAB and PSY counts by 32 and 18%, respectively, compared to 48 h milk collection. This positive impact allowed reducing up to 4°C the temperature of the heat treatment in the dairy industry, thus involving energy savings of 22%. Milking during the mornings showed a significant reduction of MAB counts in comparison to milking performed during the evenings (P<0.05). These results are highly useful for the improvement of milk quality through the optimization of collection and milking systems set at primary production.
Highlights
Milk reception in industry [6, 7]
Is study was aimed at examining the in uence of milking dayshift and the time elapsed between milking and its delivery to the industry on the mesophilic aerobic bacteria (MAB) and psychrotrophic bacteria (PSY) counts analyzed in raw milk
E largest mean value was obtained for MAB in milk collected every 48 h, with a value of 4.4 × 104 CFU/mL. is value was 10 times higher than that obtained for PSY at 24 and 48 h (4.4 × 103 and 5.4 × 103 CFU/mL, resp.). e coefficient of variance denoted a high variation in counts, which was remarkably higher for two-day collection (Table 1)
Summary
[6, 7]. In this line, some studies have used PSY counts to predict milk stability after heat treatment and packaging [7]. Storing time and temperature of raw milk from collection until reception in dairy industries is de nitely one of the key factors helping to preserve milk quality. Reducing time elapsed from milking to the heat treatment of milk might minimize spoilage due to microbial growth and enzymatic activity. To this end, the frequency of milk collection by trucks on farms should be increased from collection for every 48 hours to daily collection. Is study was aimed at examining the in uence of milking dayshift and the time elapsed between milking and its delivery to the industry (frequency of milk collection) on the MAB and PSY counts analyzed in raw milk. The impact of daily collection on energy expenditure in the industry was quanti ed
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