Effect of Different Drying Methods and Storage Time on the Retention of Bioactive Compounds and Antibacterial Activity of Wine Grape Pomace (Pinot Noir and Merlot)

Abstract

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.

Impingement drying for preparing dried apple pomace flour and its fortification in bakery and meat products

“…This phenomena is not unique to apple pomace, and as such different drying methods have been studied in various fruit pomace and vegetables (Bai et al 2013;Choicharoen et al 2009;Constenla et al 2002;de Torres et al 2010;Khanal et al 2010;Raghavan and Orsat 2007;Tseng and Zhao 2012;Yemmireddy et al 2013). Khanal et al (2010) reported that drying grape and blueberry pomaces at lower temperature for longer time (40°C for 72 h) did not cause significant losses in anthocyanins, while higher temperature drying (125°C) for a much shorter time (8 h) led to 70 % reduction.…”

Effect of Sun, Oven and Freeze-Drying on Anthocyanins, Phenolic Compounds and Antioxidant Activity of Black Grape (Ekşikara) (Vitis vinifera L.)

“…On the other hand, drying methods have a significant effect on the quality characteristics of dried fruit, such as phenolic compounds and sensorial properties (Angulo et al, 2007;Tseng & Zhao, 2012). The sun-drying method has the advantage of being more cost-effective than the other drying methods.…”

“…In addition, some studies have investigated the changes in bioactive compounds (such as total phenolic, anthocyanin, total flavonol) and antiradical scavenging activity of grape skin and pomace by using different drying methods (Larrauri et al, 1997;De Torres et al, 2010;Tseng & Zhao, 2012).…”

Influence of Temperature and Drying Time on Extraction Yield of Phenolic Compounds from Grape Pomace Variety “Portogizac”

“…Otherwise, convection drying based on heated air in different designed drying devices (cabinet driers, tunnel driers, fluid-bed driers), vacuum drying, freeze-drying, and alternative methods, such as infrared drying and microwave drying, ensure better process control, shelf-stability and microbiologically safe dried product, with minimal degradation of nutrients and sensory quality 21,22 . Several studies have investigated the effects of different drying methods on the recovery of phenolic compounds from grape pomace [32][33][34][35][36][37] . These studies have compared conventional hot air or vacuum drying with freeze-drying as a more effective drying method for by-products where material is not exposed to high temperatures resulting with preservation of organoleptic and nutritive properties of the products.…”