In view of the above data, this research effort was aimed at
further elucidating the relationship between MW of chitosans and
their antimicrobial activity upon selected common food-borne
spoilage and pathogen microorganisms, as well as the effects
of interaction with food ingredients upon the activity in
typical liquid food products. Our study used S. aureus and
E. coli as model microorganisms (one Gram-positive and one
Gram-negative, respectively), and milk and apple juice as
examples of food matrices (one rich in proteins and one rich in
carbohydrates, respectively)—including, for the first time, sensory
tests.Chitooligosaccharide mixtures, characterized by two distinct MW
(designated as o5 and o3 kDa), and with a degree of deacetylation
in the range 80–85%, were purchased from Nicechem
(Shanghai, China). The chitosans and COS tested were obtained
from crab shells.
Two food matrices were tested—UHT semi-skimmed milk
containing 1.6% (w/v) milkfat, purchased from AGROS (Porto,
Portugal); and pasteurized apple juice, obtained from Compal
(Almeirim, Portugal).
Microorganisms were from NCTC (London, UK), viz. E. coli
(NCTC 9001) and S. aureus (NCTC 8532).