No abstract

Wine grape pomace (WGP) as a source of antioxidant dietary fiber (DF) was used to fortify baked goods, including breads, muffins, and brownies. Pinot Noir WGP (RWGP) and Pinot Grigio WGP (WWGP) substituted wheat flour at concentration of 5%, 10%, and 15% for bread, 10%, 15%, 20%, and 25% RWGP for brownies, and 5%, 10%, and 15% RWGP or 10%, 15%, and 20% WWGP for muffins. The finished products were evaluated for total phenolic content (TPC), radical scavenging activity (RSA), and total DF, as well as physicochemical and sensory properties. WGP flour blends were also tested for solvent retention capacity (SRC). The highest TPC and RSA values for bread and muffins were achieved in 15% RWGP fortified samples with TPC and RSA values of 68.32 mg gallic acid equivalent (GAE)/serving and 80.70 AAE mg/serving, respectively for bread, and 2164 mg GAE/serving and 1526 mg AAE/serving, respectively for muffins. Brownies fortified with 10% RWGP had the highest RSA value (115.52 mg AAE/serving) while the control had the highest TPC value (1152 mg GAE/serving). Breads and muffins with 15% RWGP and brownies with 25% RWGP had the highest amount of DF (6.33, 12.32, and 7.73 g/serving, respectively). Sensory evaluation concluded that there is no difference in overall liking of 5% and 10% RWGP breads and muffins or 15% and 20% WGP brownies compared to the controls. This study demonstrated that WGP is a viable functional ingredient in bakery goods to increase TPC, RSA, and DF in consumer's diets.

The effects of different drying methods (40 °C conventional and vacuum oven, 25 °C ambient air and freeze dry) on the stability of two red wine grape (Pinot Noir, PN and Merlot, M) byproducts, pomace containing skins and seeds (P) and pomace containing skins only (S) were investigated. Freeze dried samples retained the highest bioactive compounds with total phenolic content (TPC) of 21.19-67.74 mg GAE/g d.m., anthocyanin content (ACY) of 0.35-0.76 mg Mal-3-glu/g d.m., DPPH antiradical scavenge activity (ARS) of 22.01-37.46 mg AAE/g d.m., and total flavanol content (TFC) of 30.16-106.61 mg CE/g d.m., followed with ambient air dried samples. All samples lost significant amount of bioactive compounds during 16 wk of storage at 15 ± 2 °C, in which ambient air and freeze dried samples had TPC reduction of 32-56% and 35-58%, respectively, but ARS in PN-P and M-P still remained more than 50 mg TE/g d.m. Overall, TPC, ARS, and TFC were higher in PN than in M, and higher in pomace than in skins, while reverse results were observed in ACY. Pomace extracts showed higher antibacterial efficiency against Listeria innocua ATCC 51142 than Escherichia coli ATCC 25922 with minimal inhibition concentration (MIC) of 3%, 6%, 4%, and 9% against E. coli, and 2%, 7%, 3%, and 8% against L. innocua for PN-P, PN-S, M-P, and M-S samples, respectively. Dietary fiber content of samples was 57-63% of total dry matter. This study demonstrated that Pinot Noir and Merlot pomace are good sources of antioxidant dietary fibers and may be incorporated into various food products as a functional ingredient. Practical Application:  Wine grape pomace (WGP), the byproduct of wine making, is a good source of polyphenols and dietary fibers and may be incorporated into various food products as a functional ingredient. This study reported the effect of four drying methods and storage at 15 ± 2 °C up to 4 months on the retention of polyphenols and antioxidant activity in two types of red WGP (with and without seeds). Antibacterial activity, dietary fiber content and the basic physicochemical properties of dried pomace powder were also reported. The information is essential for developing specific applications of the pomace.