Impact of Grape Pomace Powder on the Phenolic Bioaccessibility and on In Vitro Starch Digestibility of Wheat Based Bread

Abstract

Breads were prepared by substituting common wheat flour with 0 (GP0), 5 (GP5) and 10 (GP10) g/100 g (w/w) of grape pomace powder (GPP) and were analyzed for the phenolic profile bioaccessibility as well as the in vitro starch digestion during simulated digestion. The free and bound phenolic composition of native GPP and resulting breads were profiled using ultra-high-performance chromatography-quadrupole-time-of-flight (UHPLC-QTOF). The raw GPP was characterized by 190 polyphenols with the anthocyanins representing the most abundant class, accounting for 11.60 mg/g of cyanidin equivalents. Regarding the fortified bread, the greatest (p < 0.05) content in phenolic compounds was recorded for the GP10 sample (considering both bound and free fractions) being 127.76 mg/100 g dry matter (DM), followed by the GP5 (106.96 mg/100 g DM), and GP0 (63.76 mg/100 g DM). The use of GPP determined an increase of anthocyanins (considered the markers of the GPP inclusion), recording 20.98 mg/100 g DM in GP5 and 35.82 mg/100 g DM in GP10. The bioaccessibility of anthocyanins increased in both GP5 and GP10 breads when moving from the gastric to the small intestine in vitro digestion phase with an average value of 24%. Both the starch hydrolysis and the predicted glycemic index decreased with the progressive inclusion of GPP in bread. Present findings showed that GPP in bread could promote an antioxidant environment in the digestive tract and influence the in vitro starch digestion.

Distilled grape pomace as a functional ingredient in vegan muffins: effect on physicochemical, nutritional, rheological and sensory aspects

“…Free and bound phenolics were extracted following the protocol previously reported by Rocchetti et al . (2021). For free phenolics, a homogeniser‐assisted extraction was used (Rocchetti et al ., 2021).…”

“…Different authors evaluated the effect on technological, nutritional and sensory properties of cereal‐based foods fortified with powdered grape pomace (GPP) (Tolve et al ., 2020, 2021), and Rocchetti et al . (2021) investigated the effect of GPP on the phenolic bio‐accessibility of fortified wheat bread, showing an increase of anthocyanins bio‐accessibility and a reduction in the predicted glycaemic index of GPP‐enriched breads. Little information is however available on cereal‐based food fortification with distilled GP (DGP), which represents the by‐product from ethanol extraction.…”

Metabolomics as a Tool to Elucidate the Sensory, Nutritional and Safety Quality of Wheat Bread—A Review

“…This approach allowed the advanced characterization of grape pomace but more than that, the fortified bread samples profiling revealed the anthocyanins variation in relation to the bioaccessibility, starch hydrolysis and glycemic index. Moreover, according to the authors, these findings showed that grape pomace enriched bread could promote an antioxidant environment in the digestive tract [78]. In the same regard, Taglieri et al [79] showed that secondary metabolites from Vitellote potatoes significantly improved the phenolic content and antioxidant activity of fortified bread with the highest values when sourdough was the leavening agent.…”

Effect of the distillation process on polyphenols content of grape pomace

“…Another trouble found is the reduction of the digestibility when grape pomace is added to the ruminant diet [8], increasing the environmental impact by elevating the nitrogen requirements [9]. Nevertheless, grape pomace is a promising source of bioactive compounds [5] such as polyphenols, which have been reported to remain up to 70% in grape pomace [10]. Polyphenols are known to present not only cardio-protective, anti-inflammatory, antidiabetic, antimicrobial, among other biological activities, but also excellent properties as food preservatives due their antioxidant and antibacterial capacity [11][12][13][14].…”