The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory Study

Raw milk is the primary material for all dairy products, making it imperative to characterize and monitor its microbial composition to ensure product quality. To investigate microbial contamination from pasture to processing facilities and establish microbial traceability systems, eighty-seven raw m...

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Main Authors: Han Lu, Chongshu Dang, Ruonan Liu, Shufei Zhang, Yuling Xue, Lili Feng, Yaoguang Zhang, Yan Wu, Shijie Wang
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Journal of Food Protection
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Online Access:http://www.sciencedirect.com/science/article/pii/S0362028X25000560
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author Han Lu
Chongshu Dang
Ruonan Liu
Shufei Zhang
Yuling Xue
Lili Feng
Yaoguang Zhang
Yan Wu
Shijie Wang
author_facet Han Lu
Chongshu Dang
Ruonan Liu
Shufei Zhang
Yuling Xue
Lili Feng
Yaoguang Zhang
Yan Wu
Shijie Wang
author_sort Han Lu
collection DOAJ
description Raw milk is the primary material for all dairy products, making it imperative to characterize and monitor its microbial composition to ensure product quality. To investigate microbial contamination from pasture to processing facilities and establish microbial traceability systems, eighty-seven raw milk samples were collected from a dairy farm in Shijiazhuang of China in August. The raw milk samples were categorized into three experimental groups based on: sampling sites along the production chain (manual milking, buffer tank, filter, refrigeration tank, milk truck, and plant factory), sampling time (before dawn, morning, noon, and afternoon), and refrigeration storage (0–72 h at 12 h intervals). The microbiota were evaluated by 16S rRNA sequencing. The results identified Pseudomonas, Lactobacillus, and Prevotella as the predominant bacterial genera across all sampling conditions. The α-diversity (Shannon and Chao1) and β-diversity analysis jointly revealed significant differences in microbial communities of raw milk samples. Specifically, raw milk collected from milk truck showed distinct bacterial communities compared with upstream collecting points, while morning-collected samples showed marked compositional differences from other time points. These findings were consistently supported by cluster heatmap analysis. In addition, the relative abundance of Pseudomonas in raw milk decreased but Lactococcus and Serratia increased with refrigerated time (P < 0.05). This inverse relationship was further evidenced in cooccurrence network showing a strong negative correlation between Lactococcus, Serratia, and Pseudomonas. These results indicated where and when (after being transported to milk truck and in the morning) we need to alert owing to potential contamination in raw milk. Our results also suggested that psychrotrophic bacteria in raw milk should be paid attention, especially Pseudomonas during early refrigerated storage and Serratia during late refrigerated storage.
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spelling doaj-art-3214b544cdd94f5294dcb7d1f7740da92025-08-20T03:53:51ZengElsevierJournal of Food Protection0362-028X2025-05-0188610050410.1016/j.jfp.2025.100504The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory StudyHan Lu0Chongshu Dang1Ruonan Liu2Shufei Zhang3Yuling Xue4Lili Feng5Yaoguang Zhang6Yan Wu7Shijie Wang8College of Food Science and Biology, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China; Junlebao Dairy Co. Ltd., Shijiazhuang, Hebei 050221, China; Shanghai Jiao Tong University, Shanghai 200240, ChinaCollege of Food Science and Biology, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, ChinaJunlebao Dairy Co. Ltd., Shijiazhuang, Hebei 050221, ChinaCollege of Food Science and Biology, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, ChinaJunlebao Dairy Co. Ltd., Shijiazhuang, Hebei 050221, ChinaJunlebao Dairy Co. Ltd., Shijiazhuang, Hebei 050221, ChinaJunlebao Dairy Co. Ltd., Shijiazhuang, Hebei 050221, ChinaShanghai Jiao Tong University, Shanghai 200240, ChinaCollege of Food Science and Biology, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China; Junlebao Dairy Co. Ltd., Shijiazhuang, Hebei 050221, China; Correspondence author at: Shijiazhuang, Hebei 050221, China.Raw milk is the primary material for all dairy products, making it imperative to characterize and monitor its microbial composition to ensure product quality. To investigate microbial contamination from pasture to processing facilities and establish microbial traceability systems, eighty-seven raw milk samples were collected from a dairy farm in Shijiazhuang of China in August. The raw milk samples were categorized into three experimental groups based on: sampling sites along the production chain (manual milking, buffer tank, filter, refrigeration tank, milk truck, and plant factory), sampling time (before dawn, morning, noon, and afternoon), and refrigeration storage (0–72 h at 12 h intervals). The microbiota were evaluated by 16S rRNA sequencing. The results identified Pseudomonas, Lactobacillus, and Prevotella as the predominant bacterial genera across all sampling conditions. The α-diversity (Shannon and Chao1) and β-diversity analysis jointly revealed significant differences in microbial communities of raw milk samples. Specifically, raw milk collected from milk truck showed distinct bacterial communities compared with upstream collecting points, while morning-collected samples showed marked compositional differences from other time points. These findings were consistently supported by cluster heatmap analysis. In addition, the relative abundance of Pseudomonas in raw milk decreased but Lactococcus and Serratia increased with refrigerated time (P < 0.05). This inverse relationship was further evidenced in cooccurrence network showing a strong negative correlation between Lactococcus, Serratia, and Pseudomonas. These results indicated where and when (after being transported to milk truck and in the morning) we need to alert owing to potential contamination in raw milk. Our results also suggested that psychrotrophic bacteria in raw milk should be paid attention, especially Pseudomonas during early refrigerated storage and Serratia during late refrigerated storage.http://www.sciencedirect.com/science/article/pii/S0362028X2500056016S rRNA gene sequencingMicrobiotaMilking processingPsychrotrophic bacteriaRaw milk
spellingShingle Han Lu
Chongshu Dang
Ruonan Liu
Shufei Zhang
Yuling Xue
Lili Feng
Yaoguang Zhang
Yan Wu
Shijie Wang
The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory Study
Journal of Food Protection
16S rRNA gene sequencing
Microbiota
Milking processing
Psychrotrophic bacteria
Raw milk
title The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory Study
title_full The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory Study
title_fullStr The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory Study
title_full_unstemmed The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory Study
title_short The Effects of Sampling Sites, Collection Time, and Refrigerated Storage Duration on Microbiota of Raw Milk From a Chinese Dairy Farm: An Exploratory Study
title_sort effects of sampling sites collection time and refrigerated storage duration on microbiota of raw milk from a chinese dairy farm an exploratory study
topic 16S rRNA gene sequencing
Microbiota
Milking processing
Psychrotrophic bacteria
Raw milk
url http://www.sciencedirect.com/science/article/pii/S0362028X25000560
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