Uncovering the promising role of grape pomace as a modulator of the gut microbiome: An in-depth review.

Grape pomace is the primary wine coproduct consisting primarily of grape seeds and skins. Grape pomace holds immense potential as a functional ingredient to improve human health while its valorization can be beneficial for industrial sustainability. Pomace contains bioactive compounds, including phenols and oligosaccharides, most of which reach the colon intact, enabling interaction with the gut microbiome. Microbial analysis found that grape pomace selectively promotes the growth of many commensal bacteria strains, while other types of bacteria, including various pathogens, are highly sensitive to the pomace and its components and are inactivated. In vitro studies showed that grape pomace and its extracts inhibit the growth of pathogenic bacteria in Enterobacteriaceae family while increasing the growth and survival of some beneficial bacteria, including Bifidobacterium spp. and Lactobacillus spp. Grape pomace supplementation in mice and rats improves their gut microbiome complexity and decreases diet-induced obesity as well as related illnesses, including insulin resistance, indicating grape pomace could improve human health. A human clinical trial found that pomace, regardless of its phenolic content, had cardioprotective effects, suggesting that dietary fiber induced those health benefits. To shed light on the active components, this review explores the potential prebiotic capacity of select bioactive compounds in grape pomace.

Coupling an ion chromatography to high resolution mass spectrometry (IC-MS) for the discovery of potentially prebiotic oligosaccharides in Chardonnay grape marc.

Oligosaccharides are carbohydrates made of three to twenty monosaccharide units linked through glycosidic bonds. Emerging research into the potential prebiotic activity of oligosaccharides is creating opportunities to use industrial byproducts as value-added products. Grape marc is a residue left after winemaking and has been shown to provide health benefits to humans. In this study, we analyzed the oligosaccharides in Chardonnay grape marc by utilizing a hyphenated platform in which an ion chromatography (IC) system is coupled to an Orbitrap mass spectrometer (MS). With this platform, we obtained a structural library including 32 oligosaccharides with unique compositions of monosaccharides and 61 oligosaccharide structures. Notably, the ion chromatographic separation provided resolution of charged isomers while maintaining separation capacity for small, neutral oligosaccharides. High-quality tandem MS also facilitated the identification of oligosaccharides with structural modifications including methylation and the presence of sugar alditols and hexuronic acids. The data acquired by the IC-MS system were also compared with previously published LC-MS data. We found that these two platforms are largely complementary and, in combination, provide a more comprehensive characterization of oligosaccharides than either platform achieves alone.

Health benefits of first and second extraction drum-dried pitted olive pomace.

Olive pomace (OP) is the main by-product of olive oil extraction. After pit and skin removal, OP pulp has high concentrations of dietary fiber and phenolics with high antioxidant capacity. This study evaluated mice health benefits of drum-dried pitted OP pulp obtained after first and second oil extraction. Fresh OP was steam blanched, then pits and skins separated in a pulper/finisher, and pulp drum-dried and milled. OP was characterized by proximate analysis, total soluble phenolics (TSP), individual phenolics, and dietary fiber. Drum-dried pitted OP from first and second extraction was formulated at 10% and 20% in a high fat mice diet. Low fat (5%) and high fat (18%) control diets were also used for comparison. First extraction OP had higher TSP than OP from second extraction. Hydroxytyrosol was the main phenolic in OP. Mice weight gain was lower for the four OP diets compared to high and low-fat control diets. Fecal protein was high for all OP diets, indicating poor protein retention in mice, possibly by phenolics binding of protein and enzymes. Liver weight and adipose tissue were lower in mice consuming the four high fat OP diets compared to high fat control diet. Also, there was no effect on blood glucose by OP in diets. Mice gut microbiota analysis indicated that Actinobacteria decreased in the OP diets compared to the two control diets while Bacteroidetes increased, indicating a positive correlation with reduced body fat and weight. Drum-dried pitted OP is a novel agricultural by-product with its bioactive compounds having the potential to be incorporated in feeds and foods providing health benefits. PRACTICAL APPLICATION: Drum-dried pitted olive pomace can be produced from first or second olive oil extraction byproducts to be used as a shelf-stable healthy food or feed supplement.

Preservation of grape tomato by isochoric freezing.

This study investigated the potential of isochoric freezing to preserve tomatoes. Isochoric freezing is an emerging technology that preserves biological matter at subfreezing temperatures without any ice damage. Isochoric freezing was compared with freezing under isobaric conditions and with preservation techniques used in the food industry: cold storage at 10 °C and individual quick freezing (IQF). Physicochemical and nutritional properties were evaluated weekly for four weeks. Preservation under isochoric conditions maintained the mass, color, nutrient content (ascorbic acid, lycopene and phenolics) and antioxidant activity of the fresh tomatoes. Also, isochoric preservation led to minimal texture damage. In comparison, mass loss of tomatoes stored at 10 °C for 3 weeks contributed to changes in overall visual quality and firmness as well as significant losses in nutrient content. The greatest mass, texture, and nutrients losses were obtained for tomatoes subjected to IQF and isobaric freezing. The results show that isochoric freezing has the potential to preserve tomatoes while maintaining physicochemical and nutritional properties similar to those of fresh tomatoes which might find application in the commercial preservation of tomatoes.

Functionality of strawberry powder on frozen dairy desserts.

This study investigated the potential use of freeze-dried strawberry powder as a stabilizer in frozen dairy desserts. Five different dessert mixes were developed that contained 0%, 2.5%, 3%, 3.5%, and 4% strawberry powder. An additional dessert using strawberry extract was prepared to differentiate the effects of dietary fiber from the effect of polyphenols on sample properties. The rheological and physical characteristics of dessert mixes, fresh dessert, and stored dessert were studied. The addition of strawberry powder to dairy desserts caused an increase in the mix viscosity and a decrease in hardness and meltdown values. Complete avoidance of meltdown was achieved with the addition of 3% or greater amount of strawberry powder. The viscosity of mixes was enhanced due to the increase of total solids in the serum phase and the formation of hydrated and gel-like networks in the presence of cellulosic material, pectin, and calcium. The increase in viscosity and unfrozen water with the addition of strawberry powder also caused a reduction in ice crystallization, which resulted in softer and more stable desserts over time.

Phenolics and Antioxidant Capacity of Pitted Olive Pomace Affected by Three Drying Technologies.

This study investigated drum-drying's ability to produce dried food-grade olive pomace as a potential food ingredient that is more nutritionally dense than its freeze-dried and hot-air dried counterparts. The pits and skin were removed from fresh olive pomace, and the remaining pulp was dried to <5% moisture through freeze-drying, hot-air drying, and drum-drying at two rotational speeds. The drying treatments had no significant (P ≤ 0.05) effect on the olive pomace's fat or dietary fiber contents but did increase the L* , a* , and b* color parameter values. Although all the drying treatments significantly (P ≤ 0.05) decreased the fresh olive pomace's antioxidant capacity, drum-drying preserved the olive pomace's antioxidant capacity significantly (P ≤ 0.05) better than freeze-drying and hot-air drying. The drum-dried samples had concentrations of caffeic acid and verbascoside that were significantly (P ≤ 0.05) higher than the other dried pomace samples and were not significantly (P ≤ 0.05) different from the fresh pomace. The drum-dried olive pomace contained concentrations of hydroxytyrosol, tyrosol, vanillic acid, luteolin-7-glucoside, and rutin that were not significantly (P ≤ 0.05) different from the dried sample with the highest concentration of each respective phenolic compound. No oleuropein was found in the fresh or dried olive pomace. The results of this study show that drum-drying is an energy efficient method for converting olive pomace into a stable food-grade supplement that preserves its high phenolic, antioxidant, and dietary fiber contents to potentially benefit human health when incorporated into food or supplement products. PRACTICAL APPLICATION: Pitting and drying converts the olive pomace into a stable form that is free of physical hazards and could be incorporated into food products to increase their nutritional quality through olive pomaces' high fiber, antioxidant, and phenolic contents. Drum-drying allows food-grade olive pomace to retain higher amounts of beneficial soluble phenolics and a higher antioxidant capacity than conventional drying methods, thus furthering olive pomace's potential valorization as a food ingredient.