Formation of cereal protein disulfide-linked stable matrices by apigeninidin, a 3-deoxyanthocyanidin.

The food matrix is a factor affecting digestion rate of macronutrients, like starch. Sorghum protein networks surrounding starch have been associated with its comparatively low starch digestibility, though their formation mechanism is unclear. Since sorghums contain 3-deoxyanthocyanidins with redox property that could promote sulfhydryl-disulfide interchanges, we hypothesized that added apigeninidin (a 3-deoxyanthocyanidin) will form matrices in a non-matrix-forming cereal (corn). A model system using ovalbumin determined apigeninidin as a polymerizing agent. Starch digestion and microstructure of cereal porridges from yellow corn with and without added apigeninidin, commercial blue corn, and white sorghum were examined. Apigeninidin addition promoted protein matrices in yellow corn and attenuated initial starch digestion rate that was related to matrix formation rather than α-amylase inhibition. Blue corn with 3-deoxyanthocyanidins formed protein matrices with similar lower overall starch digestibility as sorghum. Promoting matrix formation in cereal-based foods with 3-deoxyanthocyanidins may be a strategy to modulate starch digestion rate.

Bioaccessibility, gut microbial metabolism and intestinal transport of phenolics from 100% Concord grape juice and whole grapes are similar in a simulated digestion and fecal fermentation model.

Phenolic rich 100% grape juice has been associated with many health benefits, but its place in dietary guidance is controversial relative to whole fruit. Direct comparisons of phenolic profiles and bioavailability between these food forms are needed. Phenolic bioaccessibility and metabolism from Concord (CG) and Niagara (NG) grapes and corresponding 100% juices were investigated using an in vitro digestion coupled with anaerobic gut fermentation model. Intestinal transport of resulting bioaccessible phenolics and microbial metabolites was estimated using a Caco-2 cell model. Total bioaccessible phenolics from both upper and lower digestion were similar (P > 0.05) between NG (400.9 ± 26.3 µmol per 100 g) and NGJ (349.5 ± 8.3 µmol per 100 g) and significantly different (P < 0.05) between CG (417.2 ± 24.4 µmol per 100 g) and CGJ (294.3 ± 45.4 µmol per 100 g) total cellular transport of phenolics was similar (P > 0.05) between whole grapes (89.4 ± 5.3 µmol per 100 g for CG, and 71.8 ± 2.4 µmol per 100 g for NG) and 100% juices (88.0 ± 5.6 µmol per 100 g for CGJ, and 85.3 ± 9.4 µmol per 100 g for NGJ). Differences were observed between the location of phenolic metabolism, bioaccessibility and subsequent cellular transport of individual phenolics between grapes and juice matrices. Specifically, greater amounts of phenolics were transported from grape juices than whole grapes from the upper tract. However, cumulative bioaccessibility and transport from upper and lower GI digestion/fermentation together indicates that the absorbable phenolics from 100% grape juice is similar to that of whole grapes, suggesting that phenolic-mediated health benefits from consumption of whole fruit and juice may be similar.

Bioaccessibility and intestinal cell uptake of carotenoids and chlorophylls differ in powdered spinach by the ingredient form as measured using in vitro gastrointestinal digestion and anaerobic fecal fermentation models.

Insights into food matrix factors impacting bioavailability of bioactive carotenoids and chlorophylls from fruits and vegetable ingredients are essential to understanding their ability to promote health. The stability and bioaccessibility of carotenoids and chlorophylls were assessed from dehydrated, spray-dried, freeze-dried and fresh spinach ingredient forms using in vitro models simulating upper gastrointestinal (GI) digestion and lower GI anaerobic fecal fermentation. Intestinal transport of bioaccessible bioactives from both upper and lower GI compartments was assessed using the Caco-2 human intestinal cell model. Differences in carotenoid and chlorophyll contents were observed between ingredient forms and these influenced bioaccessibility. Lower carotenoid and chlorophyll contents in spray dried spinach resulted in the lowest total bioaccessible content among all spinach treatments (5.8 ± 0.2 µmoles per g DW carotenoid and chlorophyll). The total bioaccessible content was statistically similar between freeze-dried (12.5 ± 0.6 µmoles per g DW), dehydrated (12.5 ± 3.2 µmoles per g DW), and fresh spinach (14.2 ± 1.2 µmoles per g DW). Post anaerobic fermentation, cellular accumulation of carotenoids was higher (17.57-19.52 vs. 5.11-8.56%), while that of chlorophylls was lower (3.05-5.27 vs. 5.25-6.44%), compared to those observed following upper GI digestion. Collectively, these data suggest that spinach forms created by various drying technologies deliver similar levels of bioaccessible spinach bioactives and that the lower GI tract may serve as a site for significant absorption fostered by interactions with gut microbial communities that liberate additional bioactives from the spinach matrix.

Comparative assessment of phenolic bioaccessibility from 100% grape juice and whole grapes.

Juicing of grapes includes contact with phenolic rich seeds and skins that otherwise rely on maceration for phenolic release. To understand if 100% grape juice can provide a matrix with highly bioaccessible phenolics relative to whole fruit, differences in phenolic content and bioaccessibility from commonly consumed table, Concord (CG) and Niagara (NG) grapes and their 100% juices were compared. Phenolic contents in whole grapes and 100% juices were assayed by LC-MS prior to in vitro digestion to determine phenolic bioaccessibility. Phenolic compounds were concentrated in CG and NG seeds as flavan-3-ols (222.2-285.5 mg per 100 g fw). CG skins were rich in anthocyanins (201.4 mg per 100 g fw) and flavonols (15.5 mg per 100 g fw). Product form had a significant impact on content (p < 0.01), relative bioaccessibility, and absolute bioaccessibility (p < 0.01). CG had a higher total phenolic content (21.9-50.7 mg per 100 g fw) compared to CGJ (5.8 mg per 100 g fw), though NG (4.9-10.8 mg per 100 g fw) was similar in phenolic content to NGJ (9.4-10.8 mg per 100 g fw). Absolute bioaccessibility of total phenolics from CGJ (5.2 mg per 100 g fw) was similar to CG (2.6-9.6 mg per 100 g fw), while NGJ (5.1-5.7 mg per 100 g fw) had higher bioaccessible phenolic content than NG (0.8-1.1 mg per 100 g fw). Differences in bioaccessible content were driven by high relative bioaccessibility of anthocyanins in CGJ (86-135%) compared to CG (14-39%) as well as for flavan-3-ols and phenolic acids from CGJ/NGJ (48-101; 39-85%) compared to CG/NG (0-3; 9-67%). Comparisons between juices and table grapes followed similar trends. A greater fraction of skin and seed phenolics was extracted through juicing and made bioaccessible, making 100% grape juice and whole fruit similar in phenolic delivery to consumers.

Manufacturing the ultimate green banana flour: Impact of drying and extrusion on phenolic profile and starch bioaccessibility.

Use of banana flours as functional ingredients is growing due to their nutritional benefits derived from phenolics and dietary fiber. However, the effect oven-drying, freeze-drying and extrusion on the phenolic compounds or starch digestibility is not understood. In this work, phenolic acids (gallic acid, caffeic acid), flavan-3-ols (epicatechin, catechin) and flavonols (quercetin-3-O-glucoside and myricetin) were quantified in banana flour processed by different methods. Epicatechin, the most abundant phenolic in all flours (up to 1.93 mg/100 g), was significantly reduced during thermal processing (oven-drying and extrusion). Meanwhile, phenolic acids and flavonols were found to be more thermally stable. Thus, oven-drying and extrusion generally improved the extractability of phenolic acids and flavonols. Freeze-drying resulted in native flours with significantly higher insoluble dietary fiber (up to 43.3%), although the digestible starch fraction was digested more rapidly than the oven-dried counterpart.