Grape Pomace: A Potential Ingredient for the Human Diet

Pre-Treatment Effects on Chemico-Physical Characteristics of Argan Press Cake Used for Bread Production

Argan oil is known worldwide for its nutritional, therapeutic, and cosmetic benefits. However, the extraction process produces 40-50% of argan press cake (APC), which is rich in protein, fiber, and minerals. Despite its nutritional potential, the high saponin content of APC imparts a bitter taste and anti-nutritional properties, making it unsuitable for human consumption and often wasted. This study addresses this issue by using boiling treatments with citric acid (CA) and distilled water (DW) to reduce the saponin content while evaluating the impact on APC quality. In addition, this study explores, for the first time, the incorporation of treated argan press cake, APC-CA and APC-DW, at different levels (5%, 10%, 15%, and 20%) into whole wheat flour (WWF) for bread production to improve the nutritional profile. The results indicate that both treatments significantly reduce saponin content while maintaining nutritional quality comparable to untreated APC. This includes a 50% reduction in phytic acid levels. The absence of tryptophan fluorescence emission was observed in APC-CA, which may be related to chemical degradation or interactions with other molecules. The substitution of APC-CA and APC-DW increased the protein of composite flours in a level-dependent manner. At substitution levels up to 10%, APC-CA and APC-DW positively influenced the technological properties of the bread. This study demonstrates the potential of APC to improve the nutritional value of bread and supports zero-waste initiatives by reusing by-products.

Assessing the Potential of Brewer's Spent Grain to Enhance Cookie Physicochemical and Nutritional Profiles

Brewers' spent grain (BSG), the major by-product of the brewery industry, has high nutritional value, making it suitable for upcycling into products such as healthy, and sustainable cookies. Nonetheless, the incorporation of BSG in cookies can impact their quality, given the increased fiber and protein content. This work explored the effect of replacing wheat flour with BSG at 50% and 75% in cookie formulations, focusing on physical, chemical, and sensory properties. The dietary fiber, lipid, and protein content of cookies improved considerably with the highest incorporation of BSG, increasing from 6.37% to 15.54%, 9.95% to 13.06%, and 9.59% to 12.29%, respectively. Conversely, moisture and water activity decreased from 11.03% to 3.37% and 0.742 to 0.506, respectively, forecasting a lower risk of microbial contamination and increased shelf-life. The incorporation of BSG in cookies resulted in decreased brightness and increased hardness, from 40 N to 97 N. Moreover, colorimetric shifts among the control cookies and the two BSG-rich formulations could be easily identified by an untrained observer. Sensory evaluation showed that cookies with 50% BSG retained acceptable sensory characteristics, suggesting potential for further development. Overall, BSG enhances the nutritional profile of cookies with no excessive detrimental impact on sensory features.

Polyphenolic Screening and the Antioxidant Activity of Grape Pomace Extracts of Romanian White and Red Grape Varieties

Due to its valuable organic compounds, grape pomace represents a valuable resource in the creation of value-added food products. In this study, we investigated grape pomace hydroalcoholic extracts obtained by ultrasonication from two white and two red Romanian grape varieties. The phytochemical parameters, i.e., polyphenolics, flavonoids, anthocyanins, condensed tannins content, and antioxidant activity, were determined by UV-Vis spectrometry. The statistical analysis revealed that Tămâioasă Românească and Negru de Drăgășani, respectively, and Fetească Albă and Fetească Neagră are similar to each other. Significant differences among the pomaces obtained from different grape varieties were noticed in terms of their phenolic contents. The red varieties (Fetească Neagră and Negru de Drăgășani) were richest in terms of total phenolics and total anthocyanins, respectively. The antioxidant activity of extracts obtained from grape pomace showed that Negru de Drăgășani had the higher value due to its high amounts of polyphenols, followed by Fetească Neagră, Fetească Albă, and Tămâioasă Românească. Higher levels of bioactive polyphenolic substances, i.e., catechin, myricetin, resveratrol, and vanillic acid, were found in the pomace of Negru de Drăgășani extracts using high-performance liquid chromatography. These results emphasize the potential of the Negru de Drăgășani variety to be further exploited for nutritional and functional applications.

Exploring the Benefits of Nutritional and Chemical Characteristics of Touriga Nacional and Arinto Varieties (Vitis vinifera L.)

Environmental degradation leads to an unsustainable food system. In addition to this issue, the consumption of foods that improve people's health and well-being is recommended. One of the alternatives is undoubtedly the use of by-products of winemaking, namely in the form of grape pomace flour (GPF). To verify the benefits of using the Touriga Nacional and Arinto (Vitis vinifera L.) flour varieties, analytical determinations were made to identify and quantify different components. In terms of nutritional characterization, the Touriga Nacional GPF showed results that indicate better nutritional quality than the Arinto GPF. The Touriga Nacional and Arinto samples had protein contents of 10.13% and 8.38%, polyunsaturated fatty acids of 6.66% and 5.18%, soluble dietary fiber of 14.3% and 1.7%, and insoluble dietary fiber of 55.1% and 46.4%, respectively. The anthocyanins, proanthocyanidins, and flavonols presented in samples were detected by HPLC-DAD/ESI-MS. Atomic absorption spectrometry revealed elevated concentrations of certain elements in Touriga Nacional compared to Arinto, with the former showing higher levels of aluminum (130 mg/kg) and iron (146 mg/kg) against the latter's Al (120 mg/kg) and Fe (112 mg/kg) content. GPF could become a valuable ingredient due to its nutritional quality and high content of various polyphenols.

Grape Pomace-Advances in Its Bioactivity, Health Benefits, and Food Applications

From a circular economy perspective, the appropriate management and valorization of winery wastes and by-products are crucial for sustainable development. Nowadays, grape pomace (GP) has attracted increasing interest within the food field due to its valuable content, comprising nutritional and bioactive compounds (e.g., polyphenols, organic and fatty acids, vitamins, etc.). Particularly, GP polyphenols have been recognized as exhibiting technological and health-promoting effects in different food and biological systems. Hence, GP valorization is a step toward offering new functional foods and contributing to solving waste management problems in the wine industry. On this basis, the use of GP as a food additive/ingredient in the development of novel products with technological and functional advantages has recently been proposed. In this review, we summarize the current knowledge on the bioactivity and health-promoting effects of polyphenolic-rich extracts from GP samples. Advances in GP incorporation into food formulations (enhancement of physicochemical, sensory, and nutritional quality) and information supporting the intellectual property related to GP potential applications in the food industry are also discussed.

Effect of infrared drying on chemical and microbial properties of Cold-Hardy grape pomace (Edelweiss and Marquette)

This study aims to add value to a common wine industry waste by preserving bioactive compounds in cold-hardy grape pomace (GP) and preventing any microbial growth under the proper drying conditions. Effects of infrared (IR) and hot air (HA) drying on the microbial and physicochemical properties such as color, phenolic compounds, and antioxidant activity of white (Edelweiss) and red (Marquette) GP were studied. The IR heating rapidly reduced the moisture content of GP from 55% wet basis (w.b.) to less than 10%, which resulted in a drying time reduction of 71.9% to 80.2% compared to HA drying. There were no significant differences in color parameters among the IR- and HA-dried pomaces (p > .05). The phenolic content of 'Edelweiss' pomace was not significantly affected by both IR and HA drying, whereas the phenolic content of 'Marquette' pomace was substantially reduced from 274 mg/g dry extract in raw pomace to 127 mg/g dry extract after HA drying and to 141.9 mg/g dry extract after IR drying. Overall, the microbial load on the fresh pomace samples was dramatically reduced by IR heating, with a reduction of more than 99.9% when the pomaces were dried using IR at a temperature higher than 130°C. However, this high temperature of IR led to a significant reduction of DPPH antiradical scavenge activity for 'Edelweiss' pomace (p < .05). This study shows that using the IR approach, cold-hardy 'Edelweiss' and 'Marquette' grape pomaces can be efficiently dried with the antioxidant activity maintained, which could be used in a variety of food products as a functional ingredient.

Effect of Grape Pomace Flour in Savory Crackers: Technological, Nutritional and Sensory Properties

The wine industry generates large amounts of by-products that are usually destined as waste. Grape pomace is the residue of the winemaking process and is rich in compounds with functional properties, such as dietary fiber and phenolic compounds. The aim of this research was to study the influence of white and red grape pomace flour (GPF) addition in the enhancement of functional properties of savory crackers. Different levels of incorporation were tested (5%, 10% and 15% (w/w)). Analysis of physical properties, nutritional composition and sensory acceptability were conducted to evaluate the effect of GPF incorporation. GPF cracker stability throughout a four-week period was achieved with regard to firmness and color. These products presented distinctive and appealing colors, ranging from a violet (GPF of Touriga Nacional variety) to a brown hue (GPF of Arinto variety). Concerning nutritional composition, both crackers incorporated with 10% GPF of Arinto or Touriga Nacional varieties could be considered “high in fiber”, as per the Regulation (EC) No. 1924/2006, suggesting a functional food. GPF crackers demonstrated an overall great acceptance of this kind of innovative foods, with the majority indicating that they would certainly/probably buy them. Moreover, the cracker with 10% Arinto GPF achieved the most balanced and overall preference.

The Wine Industry By-Products: Applications for Food Industry and Health Benefits

Each year, 20 million tons of wine by-products are generated, corresponding to 30% of the total quantity of vinified grapes. Wine by-products are a source of healthy bioactive molecules, such as polyphenols and other molecules (pigments, fibers, minerals, etc.). The abundance of bioactive compounds assures a promising future for nutritional foodstuff production. Wine by-products can be used to fortify aromatized waters and infusions, bread, pasta, dairy products, alcohol, sugary beverages, and processed foods. These innovative products are part of the Mediterranean diet and are of great interest to both human and environmental health. Pre-clinical studies show that consumption of food produced with wine by-products or with their extracts attenuates the inflammatory state and increases antioxidant status. As such, wine by-products provide protective effects against the underlying pathophysiological hallmarks of some chronic diseases such as atherosclerosis, diabetes, hypertension, obesity, and cancer. However, the poor bioavailability warrants further investigation on how to optimize the efficacy of wine by-products, and more clinical trials are also needed. The scientific evidence has validated the uses of the dietary nature of wine by-products and has helped to promote their use as a functional food to prevent chronic human diseases.

Evaluation of the antioxidant capacity, volatile composition and phenolic content of hybrid Vitis vinifera L. varieties sweet sapphire and sweet surprise

Bioactive compounds were extracted using two different extraction solvents (acetone and water) from pulp and whole grape berries derived from hybrid Vitis vinifera L. varieties Sweet sapphire (SP) and Sweet surprise (SU) and were characterised based on a comprehensive metabolomic approach by chromatography coupled with mass spectrometry (UPLC-QTOF-MSE and GC-FID/MS). GC-FID/MS analysis was performed with two different extraction methods (solvent extraction method and solid-phase extraction). Anthocyanins were characterised and quantified by HPLC-UV. The antioxidant potential was assessed by different assays. SP acetone extract from grape skin had the highest mean to DPPH, FRAP, ORAC and phenolic content SP samples, also showed higher anthocyanin content. Globally, 87 phenolic compounds were identified. The relative quantification by UPLC-MS^E showed flavonoids the most abundant class. Forty two compounds were found in the volatile fraction of SU, while only thirty one volatile compounds were found in the SP samples.