Biomedical Engineering Reference
In-Depth Information
Chapter 5
Biopreservation of Milk and Dairy Products
5.1
Application of Bacteriocin Preparations
5.1.1
Raw Milks
Milk may act as vehicle for human pathogenic bacteria (reviewed by Claeys et al.
2013
). Pasteurization of milk before human consumption or for the manufacture of
dairy products is often required or recommended. Pasteurizarion will decrease the
background spoilage microbiota, but it will not yield a sterile product. Some tradi-
tional, highly appreciated fermented dairy foods are still made from raw milk, and
there is an ongoing debate on the benefi ts of consuming raw milk versus pasteurized
milk (Claeys et al.
2013
). According to foodborne disease reports from different
industrialized countries, milk and milk products are implicated in 1-5 % of the total
bacterial foodborne outbreaks, with 39.1 % attributed to milk, 53.1 % to cheese and
7.8 % to other milk products (De Buyser et al.
2001
; Claeys et al.
2013
). Bacteriocins
seem an attractive approach to improve the safety of milk and dairy products (espe-
cially in those made from raw milk), and at the same time may offer some potential
technological applications such as in acceleration of cheese ripening (Table
5.1
).
The antimicrobial effects of bacteriocins and/or their produced strains have been
investigated both in raw milks and in several types of dairy products.
Many different bacteriocins preparations have been tested for preservation of
milks and dairy products, with the purpose of inactivating foodborne pathogenic or
spoilage bacteria. Addition of nisin to raw milks may help solving particular shelf-
life problems associated with hot weather temperature and/or long distance trans-
port and inadequate refrigeration systems (Davies and Delves-Broughton
1999
;
Thomas et al.
2000
). The application of nisin in combination with heat treatments
decreased the D values of bacteria such as
Bacillus cereus
and
Geobacillus stearo-
thermophilus
and natural microbiota, making it possible to apply milder thermal
treatments and at the same time extend the shelf life of milk even under poor refrig-
eration conditions. Another suggested approach was to use coatings containing
