Effect of Grape Seed Flour on the Antioxidant Profile, Textural and Sensory Properties of Waffles

Agro-Industrial By-Products of Plant Origin: Therapeutic Uses as well as Antimicrobial and Antioxidant Activity

The importance of bioactive compounds in agro-industrial by-products of plant origin lies in their direct impacts on human health. These compounds have been shown to possess antioxidant, anti-inflammatory, and antimicrobial properties, contributing to disease prevention and strengthening the immune system. In particular, the antimicrobial action of these compounds emerges as an important tool in food preservation, providing natural alternatives to synthetic preservatives and contributing to combating antimicrobial resistance. Using agro-industrial by-products of plant origin not only addresses the need to reduce waste and promote sustainability but also inaugurates a new era in the formulation of functional foods. From fruit peels to pulps and seeds, these by-products are emerging as essential ingredients in the creation of products that can promote health. Continued research in this area will unveil new applications and properties of these by-products and open doors to a food paradigm in which health and sustainability converge, paving the way to a healthier and more equitable future. The present review presents an overview of our knowledge of agro-industrial by-products and some of their more relevant health-promoting bioactivities.

Strategies to Formulate Value-Added Pastry Products from Composite Flours Based on Spelt Flour and Grape Pomace Powder

In recent years, sustainability has promoted new research to develop reformulation strategies for value-added food products by exploiting grape pomace. Grape pomace powder (GP) was used to substitute spelt flour (SF) at 0, 5, 10, 15, 20 and 25% to obtain three types of fortified pastry products: biscuits and cakes involving a chemical leavening agent, and rolls leavened by yeast. Proximate composition, total phenolic content (TPC), total flavonoids content (TFC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and ferric-reducing antioxidant power (FRAP) along with physical characteristics and sensory analysis of the enriched products were considered. The retention rate of the functional attributes of formulations in response to baking was also evaluated. Significant improvements in TPC, TFC and both antioxidant tests were achieved in the fortified products by the incremental incorporation of GP. With a substitution of 25% SF by GP, the following increases were recorded in biscuits, cakes and rolls over the control samples: 7.198-, 7.733- and 8.117-fold for TPC; 8.414-, 7.000- and 8.661-fold for TFC; 16.334-, 17.915- and 18.659-fold for FRAP and 16.384-, 17.908- and 18.775-fold for DPPH. The retention rates of TPC, TFC, FRAP and DPPH relative to the corresponding dough were 41-63%, 37-65%, 48-70% and 45-70%. The formulas leavened by yeast revealed higher functionality than those produced with a chemical raising agent. With the increase in GP, the elasticity and porosity gradually decreased for cakes and rolls, while the spread ratio of biscuits increased. Regarding sensory evaluation, all formulations with incorporated GP up to 10% were rated at an extremely pleasant acceptability level. The solutions derived from this study have great practical applicability for the development of new pastry formulations with improved functionality from GP valorisation.

Waste By-Product of Grape Seed Oil Production: Chemical Characterization for Use as a Food and Feed Supplement

Among the waste materials of wine production, grape seeds constitute an important fraction of the pomace, from which the precious edible oil is extracted. The residual mass from oil extraction, the defatted grape seeds (DGS), can be destined for composting or valorized according to the circular economy rules to produce pyrolytic biochar by gasification or pellets for integral energy recovery. Only a small quantity is used for subsequent extraction of polyphenols and tannins. In this study, we performed a chemical characterization of the DGS, by applying spectroscopic techniques (ICP-OES) to determine the metal content, separation techniques (HS-SPME-GC-MS) to evaluate the volatile fraction, and thermal methods of analysis (TGA-MS-EGA) to identify different matrix constituents. Our main goal is to obtain information about the composition of DGS and identify some bioactive compounds constituting the matrix in view of possible future applications. The results suggest that DGS can be further exploited as a dietary supplement, or as an enriching ingredient in foods, for example, in baked goods. Defatted grape seed flour can be used for both human and animal consumption, as it is a source of functional macro- and micronutrients that help in maintaining optimal health and well-being conditions.

Valorization of biowastes from sustainable viticulture with bioactive potential: application in functional yogurt

Seed and peel flours of organic Bordeaux grapes (Vitis labrusca L.), containing phenolics and antioxidant capacity, influenced both the composition and properties of a yogurt. The total phenolic content (TPC) of the yogurts containing 3% of grape seed flour (GSFY) and 3% of the mixture of flours (MFY, containing 50% of seed and 50% of peel grape flours, w/w) were 18.800 ± 1.060 and 19.509 ± 1.216 mg/g of gallic acid equivalents (GAE), respectively, significantly higher than the content of the control formulation (CY, 3.199 ± 0.326 mg GAE/g). The GSFY, MFY and CY exhibited an antioxidant capacity (mean values), respectively, of 0.6100, 0.7833 and zero µmol TEAC/g by the FRAP method; and 3.6658, 2.9217 and 0.2468 µmol TEAC/g by the ABTS method. The yogurts presented typical coloration of each flour and the texture of the yogurts did not vary significantly compared to the CY. Principal Component Analysis (PCA) results distinguished the yogurts containing the grape flours and the control sample, regarding their composition and properties. The grape bioresidues were valorized by obtaining a functional and clean label yogurt.

Graphical abstract

An Innovative, Green Cascade Protocol for Grape Stalk Valorization with Process Intensification Technologies

Valorization of agri-food residues to produce bio-based platform chemicals will enhance the transition to the bio-economy era. To this end, a sustainable process has been developed for the overall valorization of grape stalks (GS) according to a circular approach, starting from the lignin fraction to further deal with the cellulose-rich residue. This non-conventional protocol fully adheres to green chemistry principles, exploiting the so-called enabling technologies—mainly ultrasound and microwaves—for energy-saving innovative processes. Firstly, ultrasound-assisted extraction (UAE, 40 kHz, 200 W) demonstrated to be an excellent technique for GS delignification combined with natural deep eutectic solvents (NaDESs). Delignification enables isolation of the pertinent lignin framework and the potential to obtain a polyphenol-rich liquid fraction, focusing on the valorization of GS as source of bioactive compounds (BACs). Among the NaDESs employed, the combination of choline chloride (ChCl) and levulinic acid (LevA) (ChLevA) presented noteworthy results, enabling a delignification higher than 70%. LevA is one of the top-value biobased platform chemicals. In this work, a flash microwave (MW)-assisted process was subsequently applied to the cellulose-rich fraction remained after delignification, yielding 85% LevA. The regeneration of this starting compound to produce ChLevA can lead to a further biomass delignification cycle, thus developing a new cascade protocol for a full valorization of GS.

Biovalorization of Grape Stalks as Animal Feed by Solid State Fermentation Using White-Rot Fungi

This work aimed to evaluate the potential of three fungi strains, Lentinula edodes, Pleurotus eryngii, and Pleurotus citrinopileatus, to degrade lignin and enhance the nutritive value of grape stalks (GS). The GS was inoculated with the fungi and incubated under solid-state fermentation at 28 °C and 85% relative humidity for 7, 14, 21, 28, 35, and 42 days, in an incubation chamber. The influence of the treatments was evaluated by analyzing the potential modifications in the chemical composition, in vitro organic matter digestibility (IVOMD) and enzymatic kinetics. An increase (p < 0.001) in the crude protein content was observed in the GS treated with L. edodes and P. citrinopileatus at 42 days of incubation (50 and 75%, respectively). The treatment performed with L. edodes decreased (p < 0.001) lignin content by 52%, and led to higher (p < 0.001) IVOMD values at 42 days of incubation. By contrast, P. eryngii did not affect lignin content and IVOMD. A higher activity of all enzymes was also detected for the treatment with L. edodes. Results indicated that L. edodes has a great potential to enhance the nutritive value of GS as an animal feed, due to its lignin degradation selectivity.

Vegetarian “Sausages” with the Addition of Grape Flour

Vegan sausages with the addition of grape flour represent a way to reduce the intake of processed meat and at the same time to increase the intake of a healthy substance of plant origin. Grape flour obtained from grape marc as a byproduct of wine production is a source of many bioactive substances, such as antioxidants and polyphenols. The study was conducted using vegetarian sausage production: six batches of sausages with different concentrations of grape flour (0%, 1%, 3%, 7%, 10%, and 20%) were produced. The following analyses were applied for the evaluation of these vegetarian sausages: ferric reducing antioxidant power assay (FRAP), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), total polyphenolic content, total protein content, and textural and sensory parameters. The results clearly indicated that the grape seed flour addition resulted in a higher antioxidant capacity of experimentally produced vegan sausages. Based on the sensory evaluation, vegan sausages with 1% (according to taste evaluation, these samples were the most acceptable by panelists) and 3% additions of grape flour were selected as the most suitable since they were statistically more acceptable than samples produced with 20% grape flour addition. The results of this study confirm that the addition of grape flour to vegan sausages is nutritionally beneficial for consumers because it increases the antioxidant capacity and polyphenol content; however, a slight decrease in protein content was recorded too. The sustainability of the product is also achieved using the grape flour since it is a waste material generated worldwide within grape processing.

Antioxidant Potential of Cookies Formulated with Date Seed Powder

Utilising major waste products from the food industry can have both a great environmental impact and be a means to improve consumer health. Date seed is a food industry byproduct that has been proven to have high nutritional value. The aim of this work was to measure the total polyphenolic content (TPC), flavonoids, and antioxidant activity of the seeds of six date fruit varieties, Fard, Khalas, Khinaizi, Sukkary, Shaham, and Zahidi, and to use those seeds to enhance the antioxidant value of cookies by partially substituting flour with ground date seed. Date seed powder (DSP) was extracted at three levels of sample to solvent ratio (5:1, 10:1 and 15:1 mg/mL). Cookies were prepared using three substitution levels of wheat flour (2.5, 5.0, and 7.5%, w/w) by DSP and two types of flour (white and whole wheat), and were baked at two different temperatures, 180 and 200 °C. The composite cookies were found to contain a significant amount of TPC and flavonoids, and showed increased antioxidant activity compared with the control samples.

Byproducts (Flour, Meals, and Groats) from the Vegetable Oil Industry as a Potential Source of Antioxidants

The present study presents the use of photochemiluminescence assay (PCL) and 2,2 diphenyl-1-picryl-hydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), the ferric reducing antioxidant power (FRAP), and cupric ion reducing antioxidant capacity (CUPRAC) methods for the measurement of lipid-soluble antioxidant capacity (ACL) of 14 different byproducts obtained from the vegetable oil industry (flour, meals, and groats). The research showed that the analyzed samples contain significant amounts of phenolic compounds between 1.54 and 74.85 mg gallic acid per gram of byproduct. Grape seed flour extract had the highest content of total phenolic compounds, 74.85 mg GAE/g, while the lowest level was obtained for the sunflower groats, 1.54 mg GAE/g. DPPH values varied between 7.58 and 7182.53 mg Trolox/g of byproduct, and the highest antioxidant capacity corresponded to the grape seed flour (7182.53 mg Trolox/g), followed by walnut flour (1257.49 mg Trolox/g) and rapeseed meals (647.29 mg Trolox/g). Values of ABTS assay of analyzed samples were between 0 and 3500.52 mg Trolox/g of byproduct. Grape seed flour had the highest value of ABTS (3500.52 mg Trolox/g), followed by walnut flower (1423.98) and sea buckthorn flour (419.46). The highest values for FRAP method were represented by grape seed flour (4716.75 mg Trolox/g), followed by sunflower meals (1350.86 mg Trolox/g) and rapeseed flour (1034.92 mg Trolox/g). For CUPRAC assay, grape seed flour (5936.76 mg Trolox/g) and walnut flour (1202.75 mg Trolox/g) showed the highest antioxidant activity. To assess which method of determining antioxidant activity is most appropriate for the byproducts analyzed, relative antioxidant capacity index (RACI) was calculated. Depending on the RACI value of the analyzed byproducts, the rank of antioxidant capacity ranged from −209.46 (walnut flour) to 184.20 (grape seed flour). The most sensitive methods in developing RACI were FRAP (r = 0.5795) and DPPH (r = 0.5766), followed by CUPRAC (r = 0.5578) and ABTS (r = 0.4449), respectively. Strong positive correlations between the antioxidant capacity of lipid-soluble compounds measured by PCL and other methods used for determining antioxidant activity were found (r > 0.9). Analyses have shown that the different types of byproducts obtained from the vegetable oil industry have a high antioxidant activity rich in phenolic compounds, and thus their use in bakery products can improve their nutritional quality.

Wafer products with non-traditional raw materials

Fortification of recipes for products containing only refined raw materials, such as ice cream wafer cups, is a modern trend for such products. The use of soy okara in wet and dry form for these purposes allows you to unlock the potential of this raw material as an improver in the quality of wafer products. In the cup recipe, soy okara was added instead of flour dry matter in the amount of 10–30% in increments of 5%. In the wafer dough the mass fraction of moisture and spreadability were determined, in finished products - the mass fraction of moisture and wettability. It has been established that the use of wet and dry soy okara instead of the dry matter of flour in the formulations of wafer cups for ice cream allows increasing the moisture content of the dough by 2.3–4.9% and 3.6–8.8% and reducing its spreadability by 2–13 mm and 2–7 mm, respectively. In finished wafer cups, the introduction of wet and dry soy okara contributes to an increase in the mass fraction of moisture by 0.1 - 0.4% and 0.1 - 0.9%, a decrease in wetness by 2 - 22% and 2 - 15%, respectively, compared with the control sample. Rational dosage was taken 15% of dry soy okara and 20% dry soy okara instead of flour dry matter in the wafer cup recipe. At the same time, the wettability of finished products is reduced by 5–6%, which will positively affect the consumer properties of finished products when stored with ice cream. In experimental products, the amount of carbohydrates decreases by 4.9 - 5.9%, cellulose - increases by 78 and 87 times, calcium - by 1.5-1.8 times, the energy value decreases by 1.4 - 1.7%, and the biological value increases by 2.9 - 3.4% compared with control sample.

Alkali Concentration and Diluent Effects on Properties of Grape Cane Fiber-Reinforced Polymer Composites

The main objective of this study was to investigate the properties of polymer composites reinforced with grape cane fibers. The fibers were subjected to a sodium hydroxide (NaOH) treatment at two treatment concentrations to extract the fibers as well as fiber surface treatment. Panels were fabricated by hand lay-up and compression molding according to different fiber types, namely outer bark (OB) and whole (W) fibers. The whole fiber was a mixture of OB and inner bark (IB) fibers. Grape cane fibers were used as the reinforcement material for unsaturated polyester (UPE) resin panels. Acrylated epoxidized soybean oil (AESO) was used as a reactive diluent material with the UPE resin, and the results were compared with panels prepared with commercial styrene-UPE. There were inconsistent alkali treatment concentration effects on the mechanical properties and water absorption. However, panels fabricated with the whole bark fibers that have been treated with 1 wt % NaOH and had AESO-UPE resin resulted in the best tensile and flexural strength.

Dynamic Effect of Operational Regulation on the Mesophilic BioMethanation of Grape Marc

Wine production annually generates an estimated 11 million metric tonnes of grape marc (GM) worldwide. The diversion of this organic waste away from landfill and towards its use in the generation of renewable energy has been investigated. This study aimed to evaluate the effectiveness of operational parameters relating to the treatment regime and inoculum source in the extraction of methane from GM under unmixed anaerobic conditions at 35 °C. The study entailed the recirculation of a previously acclimated sludge (120 days) as downstream inoculum, an increased loading volume (1.3 kg) and a low substrate-to-inoculum ratio (10:3 SIR). The results showed that an incorporation of accessible operational controls can effectively enhance cumulative methane yield (0.145 m³ CH₄ kg⁻¹ VS), corresponding to higher amounts of digestible organics converted. The calculated average volumetric methane productivity equalled 0.8802 L CH₄ L_Work⁻¹ d⁻¹ over 33.6 days whilst moderate pollutant removal (43.50% COD removal efficiency) was achieved. Molecular analyses identified Firmicutes and Bacteroidetes phyla as core organisms for hydrolytic and fermentative stages in trophic relationships with terminal electron acceptors from the methane-producing Methanosarcina genus. Economic projections established that the cost-effective operational enhancements were sustainable for valorisation from grape marc by existing wineries and distilleries.

Biscuits Polyphenol Content Fortification through Herbs and Grape Seed Flour Addition

The study aimed to verify whether the addition of selected herbs and spices will affect the content of polyphenols in biscuits and their antioxidant capacity, as well as what impact it will have on their sensory properties and attractiveness to consumers. Ground cloves, cinnamon, mint, and grape flour were added to the biscuits in concentrations of 1.0, 3.0, 5.0, and 10.0%. The total content of polyphenols in spices and biscuit samples was determined using the Folin–Ciocalteau solution and, subsequently, the antioxidant capacity was measured by FRAP (ferric ion reducing antioxidant power) and DPPH (2,2-diphenyl-1-picrylhydrazyl inhibition). Polyphenols were transferred through spices and herbs into the biscuits in all samples and thus their antioxidant capacity was increased. The antioxidant capacity of the control sample measured by the DPPH method was 15.41%, and by the FRAP method 1.02 μmol Trolox/g. There was an increase in antioxidant capacity in all samples with the addition of spices and herbs. The highest increase was recorded in the sample with cloves, namely with the addition of 10% of cloves there was an increase measured by the DPPH method to 92.6% and by the FRAP method to 208.42 μmol Trolox/g. This also corresponds to the measured TPC (Total Polyphenol Content) in the pure clove, which was 219.09 mg GAE/g, and in the samples where the content gradually grew up to 4.51 mg GAE/g in the sample with the addition of 10%, while the polyphenol content of the control sample was 0.2 mg GAE/g. For other parameters, changes were also observed, depending on the addition of spices/herbs. There was a reduction in both texture parameters, hardness and fracturability, depending on the addition of spices/herbs, which was confirmed by both instrumental measurements and sensory analysis. Colour measurements clearly separated the control from the fortified samples, thus confirming the colour changes. The addition of grape flour shows the smallest difference from the control when the overall impression does not change with the addition. In terms of the combination of increased antioxidant capacity and overall consumer acceptability, the addition of cloves at a concentration of 3.0% appears to be the best option.

Plastic Cutlery Alternative: Case Study with Biodegradable Spoons

Plastics are mixtures of organic polymers that play a major role in environmental contamination worldwide. One way to reduce the waste arising from the use of plastics, especially disposable ones, can be to produce environmentally friendly cutlery. The aim of the work was the production of biodegradable spoons and evaluation of their texture, antioxidant activities and total polyphenols content. The spoons were made from a combination of the following ingredients: water, grape, proso millet, wheat, xanthan and palm oil in different concentrations. The samples were baked at 180 or 240 °C, some spoons were dried in a fruit dehydrator. According to the results of the analysis, a spoon prepared from a mixture of all three flours and with the addition of xanthan appears to be the most suitable replacement for plastic cutlery. This spoon showed high strength and antioxidant activity. It was confirmed that the use of grape flour has a beneficial effect on the nutritional profile of the experimentally produced biodegradable spoons.

The Influence of Hypericum perforatum L. Addition to Wheat Cookies on Their Antioxidant, Anti-Metabolic Syndrome, and Antimicrobial Properties

The aim of this study was to characterize wheat cookies enriched with 0.5% and 1.0% of Hypericum perforatum L. (St. John's wort, SJW) and determine their pro-health properties in vitro after hydrolysis in simulated gastrointestinal conditions. The results indicated that 1.0 SJW was characterized by the highest content of polyphenols, flavonoids, and phenolic acids (2.32 mg mL-1, 4.93 µg mL-1, and 12.35 µg mL-1, respectively). The enriching cookies had no effect on water absorption capacity (WAC) and oil absorption capacity (OAC). After in vitro hydrolysis, the highest peptide content was noted in 1.0 SJW (0.52 mg mL-1), and the bioactive compounds were characterized by high potential bioaccessibility (PAC), but poor bioavailability (PAV). The addition of SJW increased the ACE, α-amylase, and LOX inhibitory effect, but reduced the inhibition of pancreatic lipase. The highest antioxidant activity was noted for 1.0 SJW. The results showed that only 0.5 SJW and 1.0 SJW had slight antimicrobial activity against E. coli ATCC 25922 and B. cereus ATCC 14579 with MIC = 12.5 mg mL-1. Fractions with molecular mass <3.0 kDa were characterized with the highest p-coumaric acid content. The results show that SJW cookies had a higher content of bioactive compounds and more potent anti-metabolic syndrome effects.

Unripe Papaya By-Product: From Food Wastes to Functional Ingredients in Pancakes

Papaya is one of the most economic and valuable fruits in tropical countries. However, the fruit processing industries generate a high volume of unripe papaya waste and by-products. To reduce this waste, unripe papaya powder (UPP) was manufactured and incorporated into pancake formulation. The results showed that a particle size of UPP was 140.8 ± 2.1 µm, which contained polyphenolic compounds, dietary fiber and demonstrated ferric reducing antioxidant power (FRAP). Compared with wheat flour, UPP had higher values of water absorption index, water solubility index and swelling index and lower level of amylose. In the cholesterol-reducing effect, UPP decreased the formation of cholesterol micellization and bound bile acids. Interestingly, incorporation of 5-20% UPP into pancakes could decrease the glucose release with a concomitant increase in the percentage of undigestible starch. The hardness and chewiness of pancake was increased with a higher amount of UPP (10-20%). The results suggest that UPP from fruit processing waste can be regarded as a promising functional ingredient to incorporate with pancakes.