Short communication: Snapshot of industry milk hauling practices in the western United States

Kuhn, Eva; Meunier-Goddik, Lisbeth; Waite‐Cusic, Joy

doi:10.3168/jds.2017-13279

Cited by 2 publications

(1 citation statement)

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“…Repeated tanker usage maximizes milk collection efficiency and reduces water, chemical, and energy usage. Tanker usage frequency varies depending on size and location of the processing facility but can be typically categorized as (1) high-frequency hauling, where several loads will be collected within 24 h from producers within a short distance from the processing facility; and (2) low-frequency hauling, in which a tanker may remain empty and dirty (parked/idle or en route) for an extended period between loads (Darchuk et al, 2015a,b;Kuhn et al, 2018). Members of the dairy industry are concerned that extended periods between loads at elevated temperatures could promote microbiological growth in the tanker that could affect subsequent loads of milk.…”

Section: Introductionmentioning

confidence: 99%

Effect of leaving milk trucks empty and idle for 6 h between raw milk loads

Kuhn

Meunier-Goddik

Waite‐Cusic

2018

Journal of Dairy Science

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The US Pasteurized Milk Ordinance (PMO) allows milk tanker trucks to be used repeatedly for 24 h before mandatory clean-in-place cleaning, but no specifications are given for the length of time a tanker can be empty between loads. We defined a worst-case hauling scenario as a hauling vessel left empty and dirty (idle) for extended periods between loads, especially in warm weather. Initial studies were conducted using 5-gallon milk cans (pilot-scale) as a proof-of-concept and to demonstrate that extended idle time intervals could contribute to compromised raw milk quality. Based on pilot-scale results, a commercial hauling study was conducted through partnership with a Pacific Northwest dairy co-op to verify that extended idle times of 6 h between loads have minimal influence on the microbiological populations and enzyme activity in subsequent loads of milk. Milk cans were used to haul raw milk (load 1), emptied, incubated at 30°C for 3, 6, 10, and 20 h, and refilled with commercially pasteurized whole milk (load 2) to measure cross-contamination. For the commercial-scale study, a single tanker was filled with milk from a farm known to have poorer quality milk (farm A, load 1), emptied, and refilled immediately (0 h) or after a delay (6 h) with milk from a farm known to have superior quality milk (farm B, load 2). In both experiments, milk samples were obtained from each farm's bulk tank and from the milk can or tanker before unloading. Each sample was microbiologically assessed for standard plate count (SPC), lactic acid bacteria (LAB), and coliform counts. Selected isolates were assessed for lipolytic and proteolytic activity using spirit blue agar and skim milk agar, respectively. The pilot-scale experiment effectively demonstrated that extended periods of idle (>3 h) of soiled hauling vessels can significantly affect the microbiological quality of raw milk in subsequent loads; however, extended idle times of 6 h or less would not measurably compromise milk quality in subsequent loads in commercial tankers. Current tanker sanitation practices appear to be sufficient for maintaining raw milk SPC, LAB, and coliform levels, which are important measures of milk quality.

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Section: Introductionmentioning

confidence: 99%