Dhiraj Vattem

SOLID-STATE PRODUCTION OF PHENOLIC ANTIOXIDANTS FROM CRANBERRY POMACE BY RHIZOPUS OLIGOSPORUS

ABSTRACT Cranberry pomace is a byproduct of the cranberry processing industry that can be targeted for production of value-added phenolic ingredients. Bio-processing of pomace by solid state fermentation (SSF) using food grade fungi provides unique strategies to improve nutraceutical properties and to produce functional phenolic ingredients. Several functional phenolic phytochemicals exist as glycosides or as other conjugated forms with reduced biological activity. We hypothesize that during SSF the fungal glycosidases mobilize some phenolic antioxidants in cranberry pomace and their activity by hydrolysis via β-glucosidase and releasing the aglycone. To develop this strategy we used food grade fungus Rhizopus oligosporus. Our goal was to target the release of simple phenolic aglycones and mobilized diphenyls. SSF of cranberry pomace was done for 16 days with nitrogen sources, ammonium nitrate (NH4NO3) and fish protein hydrolysate (FPH). The two nitrogen treatments increased water extractable phenolics by 15–26% by day 10 in the pomace. Antioxidant protection factor was highest on day 10 for both nitrogen treatments and was 20–25% higher than control for water extracts and 16.5–19.5% for ethanol extracts. The DPPH radical inhibition (DRI) capacity increased by 5% only for the NH4NO3 treatment and gradually decreased for FPH treatment in water extracts. There was no significant change in DRI of the ethanol extracts. The β-glucosidase activity increased by 60-fold for NH4NO3 treatment and by over 100-fold for FPH treatment and correlated well with the increase in the extractable phenolics and antioxidant activity. Changes in diphenyl profiles during the solid-state process analyzed using HPLC indicated that ellagic acid increased by 4–5 fold in water extracts for both the nitrogen treatments. This increase was between 15–27% in the ethanol extracts. We conclude that SSF of cranberry pomace increased the antioxidant activity concurrent with increased β-glucosidase activity. The HPLC profile showed ellagic acid, a compound with anti-carcinogenic properties was enriched. The antioxidant function has implications for prevention of major oxidation-linked diseases such as cancer and CVD. This value-added SSF strategy is an innovative approach to enhance nutraceutically-relevant functional phytochemicals for food and feed applications.

Ellagic acid production and phenolic antioxidant activity in cranberry pomace (Vaccinium macrocarpon) mediated by Lentinus edodes using a solid-state system

Abstract Cranberry pomace is a byproduct of the cranberry processing industry that can be targeted for production of value-added phenolic ingredients. Bio-processing of pomace by a solid state process using food grade fungi provides a unique strategy to improve nutraceutical properties and to produce functional phenolic ingredients. The investigation was carried out to understand the changes and mobilizations of simple phenolics and diphenyls and their antioxidant properties in cranberry pomace processed by solid-state growth using food grade fungus Lentinus edodes . The role of β-glucosidase in the mobilization of phenolic antioxidants by hydrolysis of the glycosides was also investigated. During the course of solid-state growth there was an increase in the extractable phenolic content. Antioxidant activity measured by both 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) inhibition system and β-carotene oxidation model system increased over the course of growth. Both phenolics and antioxidant capacity correlated with the increase in the β-glucosidase activity and peaked in a similar manner, showing that the enzyme may play an important role in the release of phenolic aglycones from cranberry pomace and, therefore, increase the antioxidant capacity. In addition, HPLC analysis indicated that the cranberry pomace was enriched with ellagic acid to a level of 350 μg/g dw of pomace.

Acrylamide in food: a model for mechanism of formation and its reduction

Abstract Acrylamide and its analogues have been widely used since the last century for various chemical and environmental applications and can be formed by heating of biological material derived from plant tissues. This compound, identified previously as a potential industrial hazard, has now been found in many cooked foods. Reports of the presence of acrylamide in a range of fried and oven-cooked foods have caused worldwide concern because of its probable carcinogenicity in humans. The exact mechanism for the acrylamide formation in food is not well understood. The existing models to explain its formation have several limitations. This study was carried out to investigate the acrylamide formation in commonly consumed food stuff model and possible mechanisms of its reduction. Our system uses fried potato slices previously treated either with phenolic antioxidants from cranberry and oregano or coated with chickpea batter. We have shown that formation of acrylamide in fried potato chips is not an oxidative phenomenon and can be reduced by protective effects of chick pea proteins. Based on the results of our investigation we have proposed a non-oxidative model for acrylamide formation.

Enrichment of Phenolic Antioxidants and Anti-Helicobacter pylori Properties of Cranberry Pomace by Solid-State Bioprocessing

Cranberry pomace modified by solid-state bioprocessing with the food-grade fungi Rhizopus oligosporus and Lentinus edodes was investigated for antimicrobial effects against Helicobacter pylori. The results indicated that solid-state bioprocessing enriched the cranberry pomace with phenolic antioxidants and important phenolic phytochemicals such as ellagic acid. The antimicrobial activity of the extracts against H. pyloriwas also enriched by solid-state bioprocessing. Further, the results also indicated that the antimicrobial activity correlated strongly with total soluble phenolic content and ellagic acid, suggesting different modes of antimicrobial function. A dose-dependent analysis of antimicrobial activity suggested that there could be a possible synergistic mode of interaction between the phenolic phytochemicals. Solid-state bioprocessing of cranberry pomace using the food-grade fungi R. oligosporus and L. edodes could therefore be an innovative approach to develop antimicrobial ingredients for dietary management of H. pylori infections.