Similarities and differences among fluid milk products: traditionally produced, extended shelf life and ultrahigh-temperature processed

Abstract

Extended shelf life milk is a relatively new kind of fluid milk, generally manufactured by high-temperature treatment and/or micro-filtration. Being advertised as 'pasteurized milk with an extended shelf life', its flavour, compositional quality and labelling was questioned. Extended shelf life (high-temperature treatment), pasteurized ('traditionally produced') and ultrahigh-temperature milk were, therefore, compared at the beginning and end of shelf life. In triangle tests, panellists distinguished clearly between all products. High-temperature treatment milk's flavour was closer to ultrahigh-temperature and traditionally produced milk in the beginning and at the end of shelf life, respectively. Physicochemically and bacteriologically, all three types could be distinguished. Since 'extended shelf life' comprises many process varieties (each affecting flavour differently), consumer information and appropriate package labelling beyond 'long-lasting' is necessary, e.g. by mentioning the heat treatment applied.

Identification of the Peptide PyroQ-βCasein194–209 as a Highly Specific and Sensitive Marker to Differentiate between Ultrahigh-Temperature Processed (UHT) Milk and Mildly Heated Milk

“…Industrial heating of milk guarantees microbial safety and reduces enzyme activity to prolong the food’s shelf life. Milk industry uses several heating technologies that result in different milk types, such as traditionally pasteurized milk, ultrahigh-temperature processed (UHT) milk, and sterilized milk. − Traditionally, pasteurized milk is heated at 72 °C for 15 s (or equivalent), whereas conventional UHT milk undergoes 2–4 s of direct heating by steam injection at 140–145 °C or indirect heating by coils or plates at 136–138 °C. , In the past decade, a new milk type was introduced into the European market to fill the gap between pasteurized and UHT milk. Under refrigerated conditions, this “extended shelf life” (ESL) milk provides longer shelf life than pasteurized milk but similar sensory properties .…”

“…Under refrigerated conditions, this “extended shelf life” (ESL) milk provides longer shelf life than pasteurized milk but similar sensory properties . Because there is no legal definition, ESL milk is produced by various techniques: either raw milk is pasteurized after a microfiltration step reducing the bacterial load or the milk is subjected to a higher heat load compared to traditional pasteurization, commonly to 120–130 °C for 1–4 s of direct or indirect heating. ,, Thermal processing influences milk and its constituents to an extent related to the applied heat load . Vitamins are degraded, , whey proteins are denaturated, and amine groups of proteins are modified by lactose and its breakdown products .…”