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.