In this study, whey protein concentrate (WPC) was sonicated or partially hydrolyzed by Alcalase, then examined as an emulsifier and carrier for the emulsification and spray drying of grape seed oil (GSO)-in-water emulsions. The modification treatments increased the free amino acid content and antioxidant activity (against DPPH and ABTS free radicals), as well as, the solubility, emulsifying, and foaming activities of WPC. The modified WPC-stabilized emulsions had smaller, more homogeneous droplets and a higher zeta potential as compared to intact WPC. The corresponding spray-dried powders also showed improved encapsulation efficiency, oxidative stability, reconstitution ability, flowability, solubility, and hygroscopicity. The morphology of particles obtained from the primary WPC (matrix type, irregular with surface pores) and modified WPC (reservoir type, wrinkled with surface indentations), as well as the oxidative stability of the GSO were influenced by the functional characteristics and antioxidant activity of the carriers. Changes in the secondary structures and amide regions of WPC, as well as the embedding of GSO in its matrix, were deduced from FTIR spectra after modifications. Partial enzymolysis had better results than ultrasonication; hence, the WPC hydrolysates are recommended as emulsifiers, carriers, and antioxidants for the delivery and protection of bioactive compounds.
Brassica vegetables, particularly turnip, contain many natural antioxidants. This
review focuses on antioxidant components and the influence of different processing and storage
conditions on antioxidant activities of some Brassica vegetables including turnip. Long
storage times had an adverse effect on antioxidant value of turnip. Also, the activity of antioxidants
in cruciferous vegetables could be influenced by antioxidant breakdown and leaching
during cooking. Heat treatment has a major impact on the antioxidant activity of Brassica
vegetables and it has been perceived minor antioxidant ability in processed vegetables compared
with uncooked samples. Food processing operations in terms of blanching, canning,
sterilizing and freezing, in addition to cooking methods perhaps can have a major influence on
the yield, chemical structure and bioavailability of antioxidants in Brassica family. Cooking
methods such as steaming and microwaving are proper methods for a short time. Consumption
of raw or slightly blanched turnip is an appropriate way to maximize its health benefits.
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