ID: 2265

• Title:
  Bacterial microbiome of goat’s cheese produced with milk subjected to pulsed electric fields
  
  Authors:
  

  Fernandes, Paulo
  Araújo, Alberta
  Barbosa, Carla
  Romão, Alexandre
  Alves, Rui

  
  
  Abstract:
  Goat's milk is recognized for its higher heat sensitivity compared to cow's milk, primarily attributed to its distinct composition and physicochemical properties. As a result, when exposed to traditional thermal treatments, goat's milk exhibits lower heat stability, rendering it more vulnerable to damage and adversely affecting its organoleptic qualities. To address this issue and ensure microbiological safety, alternative approaches such as pulsed electric fields (PEF) may provide a viable solution to mitigate microbial risks and simultaneously preserve the quality and nutritional stability of goat’s milk. The viability of bacterial cells exposed to pulsed electric fields (PEF) is contingent upon various factors, including the characteristics of the medium (e.g., conductivity) and the specific type and size of the cells being targeted. We produced cheeses using heat-treated goat's milk at 75 °C for 3.4 seconds, as well as milk treated with PEF (10 kV/cm, 50 µs pulse width, 3 Hz), followed by heat treatment at 63 °C for 6.0 seconds. Both conditions assured a 5 log decrease in the counts of L. monocytogenes ATCC 13932. The cheeses were then aged for 25 days, and samples were collected at 5, 15, and 25 days. After extracting and purifying DNA, a high-throughput sequencing of 16S amplicons using the MiSeq Illumina platform has been conducted. Comparing the α-diversity indices (Simpson, ACE, Chao1, and Shannon) of the bacterial populations in both types of cheese revealed similar species richness and abundance. However, the cheese made with PEF-treated milk exhibited a slightly lower species diversity with an uneven distribution of relative abundance. Nevertheless, when examining the composition of the bacterial communities in the two types of cheese, including species presence/absence and relative abundance, significant differences were observed. This was confirmed by a Weighted UniFrac analysis (p=0.02612) and an Analysis of Similarities (ANOSIM, p=0.04), indicating an impact on the development of the starter culture. A LEfSe analysis revealed significant differences in specific taxa between the two groups of cheeses. Notably, Lactococcus lactis was found to be significantly more prevalent (p=0.014) in cheeses produced using PEF+HT milk compared to cheeses made with HT milk. The findings suggest that PEF alongside mild heat pasteurization may be suitable as an alternative processing method of goat milk for cheese production.
  
  
  
  Acknowledgements: This work was funded by UIDB/05937/2020 and UIDP/05937/2020 – CISAS, funded by national funds, through FCT – Fundação para a Ciência e a Tecnologia.
  
  
  
  Keywords:
  cheese, microbiome, PEF
  
  Refs:
  
  
  Topic 1:
  10. Food safety and food preservation
  
  Topic 2:
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