Physico-Chemical Changes, Microbiological Properties, and Storage Shelf Life of Cow and Goat Milk from Industrial High-Pressure Processing

Sok Fern Tan,Tuan Poy Tee,Nyuk Ling Chin,Sook Kuan Chooi

doi:10.3390/pr8060697

Abstract

Industrial high-pressure processing (HPP) was conducted on cow and goat milk in comparison to conventional heat pasteurization. No significant changes were found in the physico-chemical properties of the treated milk except for pH, where pasteurized cow milk experienced a decrease while goat milk’s pH increased for both pasteurized and HPP treated. HPP-treated cow and goat milk both achieved microbial shelf life of 22 days at 8 °C storage with no increase in Bacillus cereus, mesophilic aerobic spores, coliform, yeast and mold but slight increase in psychrotrophic bacteria and total plate count. Pasteurized goat milk was spoilt at the end of storage with exceeding count of psychrotrophic bacteria (9.0 × 108 CFU/mL) and total plate count (3.5 × 108 CFU/mL). HPP-treated cow milk exhibited higher physico-chemical stability than goat milk as evidenced by non-significant change of titratable acidity but goat milk experienced an increase of 0.04% averagely.

Highlights

Milk is well-known as a major source of dietary energy, protein, and fat
The results recognized that high-pressure processing (HPP) treatment of 7 min at 450 MPa is sufficient to render both cow and goat milk a shelf life of 22 days at 8 ◦ C, higher pressure of 600 MPa can give a better safety margin with best treatment results in the order of 600 MPa/7 min, 600 MPa/5 min, and lastly
The HPP treatment has shown better capability of preserving milk than pasteurization where pasteurized goat milk was considered spoilt during storage since both total plate count (TPC) and psychrotrophic bacteria count exceeded the permissible limit

Summary

Introduction

Milk is well-known as a major source of dietary energy, protein, and fat. It contributes 134 kcal of energy/capita per day on average [1]. Apart from cow milk, goat milk has started to gain interest worldwide in recent years [2]. Goat milk contains lower amount of caseins by 89% compared to cow milk, gives a greater digestive utilization compared to cow milk [3]. The nature of milk and its chemical composition render it as one of the ideal culture media for microbial growth and multiplication [4]. The major challenge in milk industries is to ensure delivery of safe and healthy milk products of consistent quality to an ever-increasing demand of milk

Methods

Results

Conclusion