Optimization of Raw Ewes' Milk High-Pressure Pre-Treatment for Improved Production of Raw Milk Cheese.

Rita S Inácio,Rui Barros,Ana M P Gomes,Jorge A Saraiva

doi:10.3390/foods11030435

Abstract

Serra da Estrela protected designation of origin (PDO) cheese is manufactured with raw milk from Bordaleira and/or Churra Mondegueira da Serra da Estrela sheep breeds. Several socio-environmental shortcomings have reduced production capacity; hence, treatments that may contribute to its efficient transformation into cheese are welcome. High-pressure processing (HPP) milk pre-treatment may contribute to a cheese yield increment, yet optimization of processing conditions is warranted. An initial wide-scope screening experiment allowed for pinpointing pressure intensity, holding time under pressure and time after HPP as the most important factors influencing curd yield. Based on this, a more targeted screening experiment allowed for selecting the range of experimental conditions to be used for an experimental design study that revealed an HPP treatment at 121 MPa for 30 min as the optimum for milk processing to improve curd yield (>9%) and effectively maintain the beneficial cheese microbiota; the optimum was validated in a final experimental framework.

Highlights

Academic Editors: Anet RežekIn cheesemaking, the cheese yield is of particular economic interest since small differences in yield translate into big differences in both milk volume savings and final profits; the higher the solids percentage recovered, the greater the amount of cheese obtained, reflecting economic gains
Firmer curds were obtained from High-pressure processing (HPP) processed milk for 5 min, while the milk treated for 30 min resulted in a curd/paste similar to a granular whey cheese (Figure S1)
In a study performed with ovine milk, authors achieved results that support those presented in the current study; they were able to show that coagulation time decreased slightly after HPP 100 MPa for 30 min and increased significantly after

Summary

Introduction

Academic Editors: Anet RežekIn cheesemaking, the cheese yield (kg cheese/kg milk) is of particular economic interest since small differences in yield translate into big differences in both milk volume savings and final profits; the higher the solids percentage recovered, the greater the amount of cheese obtained, reflecting economic gains. In the particular case of the protected designation of origin (PDO) Serra da Estrela ewe cheese, the available milk is becoming scarcer due to limitations of various kinds, such as environmental and social cues. High-pressure processing (HPP) is a non-thermal food processing technology, wherein the food is subjected to a very high pressure range from 100–800 MPa during a holding period between 5–60 min. Different literature reports have indicated that HPP milk pretreatment can increase curd yield [4,5]. Milk HPP has the potential to reduce viable cell numbers of undesirable contaminant micro-organisms, without significant effects on flavour and nutritional components, contributing to safer high-quality cheese products; HPP may influence the physicochemical and technological properties of the milk [6,7,8]. The effect of HPP on the curd yield has been evaluated mainly in cows’

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