Within 4 h at 103 cells/mL, all five compounds, at every
concentration (0.5%, 0.25% and 0.1%, w/v), proved to be bactericidal; for higher inocula, 0.1% (w/v) was
only bacteriostatic; at 107 or 105 cells/mL, and independently of the inoculum level, 0.25% (w/v) of any
chitooligosaccharide (COS) mixture was sufficient to reduce the E. coli initial population by at least 3 log
cycles; COS never exhibited bactericidal action over S. aureus, unlike high and medium MW
chitosans—which, at 0.5% (w/v), presented a bactericidal effect even against 107 cells/mL. When
incorporated in liquid food matrices, medium and high MW chitosans maintained their activity, for both
matrices and bacteria, although a slower activity was noticeable in milk; however, COS lost their activity
upon both bacteria in milk after 4–8 h. Furthermore, addition of chitosans to apple juice led to several
unpleasant off-flavors, such as astringency and after taste—which increased in magnitude with MW