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Effect of Nitrogen Flushing on the Production of Proteinase by Psychrotrophic Bacteria in Raw Milk
Author(s) -
MURRAY S.K.,
KWAN K.K.H.,
SKURA B.J.,
McKELLAR R.C.
Publication year - 1983
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1983.tb09183.x
Subject(s) - casein , raw milk , food science , psychrotrophic bacteria , chemistry , proteolytic enzymes , bacteria , nitrogen , lactic acid , biology , enzyme , biochemistry , organic chemistry , genetics
Raw milk was flushed with 100 ml N 2 min ‐1 during storage at 4°C. Microflora (total psychrotrophs, proteolytic psychrotrophs, lactic acid bacteria) in nitrogen‐flushed milk exhibited a longer lag phase and slower growth rates than those in milk stored aerobically at 4°C. Although proteolytic psychrotrophs grew in nitrogen‐flushed milk, proteinases could not be detected in these milk samples. Proteinase assays and electrophoresis showed extensive proteolytic activity and hydrolysis of β‐casein in control milk but no detectable casein degradation in nitrogen‐flushed milk, even after storage for 18 days at 4°C. This study shows the potential of controlled atmosphere storage of raw milk for inhibition of the accumulation of proteolytic enzymes from psychrotrophic bacteria.