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Pomegranate peel extract (PPE), a by-product of the pomegranate juice industry with potential health effects, was explored for use to fortify reconstituted apple juice in the concentration range 0.5 to 2.0% (w/w). Radical scavenging and antioxidative capacities of the fortified apple juices were evaluated using (i) electron spin resonance (ESR) to quantify their ability to scavenge the stable radical Fremy's salt and (ii) the Trolox equivalent antioxidant capacity (TEAC) assay and compared to apple juice without fortification as control. The highest antioxidative capacity was found in the apple juice fortified with the highest percentage of pomegranate peel extract, while the optimal sensory quality was found by addition of 0.5 g PPE per 100 mL. The Artemia salina assay was used as a fast screening method for evaluating overall toxicity, and showed little toxicity with up to 1.0 g per 100 mL addition of PPE, but increasing toxicity at higher concentrations. Accordingly, it is important to balance addition of PPE, when used for enrichment of apple juice in order to obtain a healthier product, without compromising the sensorial quality or toxicological safety of the apple juice. Concentrations between 0.5 and 1.0 g PPE per 100 mL seem to be acceptable.

Grape seed extract (GSE), a by-product from the wine industry, was explored for its use as enrichment to mayonnaise, due to its potential health effects. Mayonnaises were enriched with 0 mg GSE per mL, 0.5 mg GSE per mL (similar to 0.050%), 0.9 mg GSE per mL (similar to 0.10%) and 1.4 mg GSE per mL (similar to 0.15%) during preparation and stored in the dark at room temperature for 8 weeks. The antioxidative capacity of the mayonnaises was evaluated by their ability to scavenge the stable radical TEMPO by electron spin resonance (ESR) spectroscopy. The oxidative stability of the mayonnaises was determined by the content of lipid hydroperoxides (peroxide value, POV), the content of conjugated diene hydroperoxides and the content of thiobarbituric acid reactive substances (TBARS). The highest antioxidative capacity and the lowest content of lipid hydroperoxides and TBARS were found in the mayonnaise with the highest percentage of GSE (0.15%). Therefore, the oxidative stability of the mayonnaises enriched with GSE was slightly improved through storage. However, mayonnaise without GSE had the highest sensorial acceptability compared to mayonnaise enriched with GSE. In the Artemia salina assay, a fast screening method for overall toxicity, the death rate of brine shrimps larvae was found to increase for increasing percentage of GSE. A level of 0.05% GSE in mayonnaise is concluded not to constitute any toxicological risks, but to provide significant protection against oxidation during storage.

Pomegranate peel powder (PP), a by-product of the pomegranate juice industry rich in polyphenols, was explored for use in bread production, due to its potential health effects. Wheat bread was prepared using different levels for replacement of flour with PP (0 to 10 g per 100 g flour) resulting in antioxidant levels expressed as Trolox equivalent antioxidant capacity values (TEAC) ranging from 1.8 to 6.8 μmol TEAC per g bread for fresh bread. TEAC remained constant during 5 days of storage in polyethylene bags at room temperature. The oxidative stability was evaluated by detection of radicals by direct electron spin resonance (ESR) spectroscopy, and peroxide value, and the highest capacity of scavenging of radicals (Fremy's salt) and the lowest content of peroxide values were found in bread with the highest percentage of PP. Safety evaluation was performed by the Artemia salina assay. An increased death rate of the brine shrimp larvae was found as a function of the replacement of wheat flour with PP in fortified bread providing a general screening method for the toxicological test of polyphenol fortified bread to be recommended for use in product development in addition to subjective evaluation. Based on both toxicological and subjective evaluations an addition of 2.5% PP is recommended for the actual product.