This review aims to familiarize the reader with research efforts on the cultivation media of lactic acid bacteria (LAB). We have also included a brief discussion on standard ingredients used in LAB media and chemically defined media as related to bacterial growth requirements. Recent research has focused on modifying standard media for the enumeration, differentiation, isolation, and identification of starter cultures and probiotics. Even though large numbers of these media have been developed to serve dairy microbial control, they have failed to provide consistent results. The research consequently points to the need to develop a reliable lactobacilli growth medium for the dairy industry.

The effects of low and high frequency ultrasound on the production of volatile compounds along with their derivation and corresponding off-flavours in milk and milk products are discussed in this review. The review will simultaneously discuss possible mechanisms of applied ultrasound and their respective chemical and physical effects on milk components in relation to the production of volatile compounds. Ultrasound offers potential benefits in dairy applications over conventional heat treatment processes. Physical effects enhance the positive alteration of the physicochemical properties of milk proteins and fat. However, chemical effects propagated by free radical generation cause redox oxidations which in turn produce undesirable volatile compounds such as aldehydes, ketones, acids, esters, alcohols and sulphur, producing off-flavours. The extent of volatile compounds produced depends on ultrasonic processing conditions such as sonication time, temperature and frequency. Low frequency ultrasound limits free radical formation and results in few volatile compounds, while high ultrasonic frequency induces greater level of free radical formation. Furthermore, the compositional variations in terms of milk proteins and fat within the milk systems influence the production of volatile compounds. These factors could be controlled and optimized to reduce the production of undesirable volatiles, eliminate off-flavours, and promote the application of ultrasound technology in the dairy field.

Biofilm formation is a prevalent contamination source in the dairy processing industry. It enhances the tolerance of bacterial cells and elevates the risk of product spoilage. Moreover, biofilms can present significant challenges to dairy processing equipment, thereby threatening the safety and efficiency of operations. In the dairy product processing environment, biofilms typically appear as mixed biofilms. Compared to single-species biofilms, mixed biofilms are characterized by high diversity, complex spatial distribution, strong antibiotic resistance and high adaptability to environmental conditions. Consequently, it is essential to comprehensively understand the formation mechanisms and characteristics of mixed biofilms and develop effective control strategies. This review provides an overview of the formation of common microbial biofilms and their mixed biofilms during dairy processing, describes the cellular interactions and characteristics, and finally outlines current common biofilm control measures. All of these efforts aim to provide valuable insights for reducing risks associated with mixed biofilms in the dairy environment.