Amorphous State of Grape Functional Confection Dictates Differences in Bioactive Compound Release

Abstract

Fruit bioactives applied to the oral cavity has been shown to successfully treat oral maladies. Grape phytochemicals such as polyphenols, chalcones, and stilbenes have shown in previous studies to exhibit anti-neoplastic, anti-inflammatory, and anti-atherogenic properties. Localized release of bioactives in the mouth at a desired rate is the goal of controlled release formulations. Liquids spread too easily in the mouth and would dilute the active compounds therefore solids are more desirable. Food solids can exist as glassy, crystalline or rubbery physical states. Variation in moisture content and confection constituents, modulate between the glassy (hard candy model) and rubbery (gummy candy) forms. Therefore the state of the amorphous phases can dictate the rate of absorption of grape bioactives by buccal tissues. By differing soy protein and water inclusions, amorphous grape confections with a variety of physico-chemical and rheological characteristics were obtained. Glassy forms (5g) contained grape juice, high fructose, and sucrose while rubbery (6g) gummy contained grape juice, acid-thinned wheat starch and varying amounts of soy protein (0,25, and 50%). Increases in soy protein concentration attenuated starch gelation by weakening gel structure. Physical state dramatically influences dissolution rate thus limits the rate at which oral tissues can absorb these compounds. Dissolution studies revealed three release kinetics of bioactive ingredients in grape confections (hard candy versus soft gummy). Differences in the confection amorphous phase rheological properties related to differences in dissolution rate. Since the rate-limiting step to drug solubility/release is dissolution, its differences are expected to mitigate the mechanism of bioactive release within the amorphous food forms.