Onion skin — Raw material for the production of supplement that enhances the health-beneficial properties of wheat bread

Influence of Pretreatments and Freeze-Drying Conditions of Strawberries on Drying Kinetics and Physicochemical Properties

The aim of this study is to analyze the effects of pretreatments and drying temperature on the freeze-drying (FD) kinetics, ascorbic acid content, color changes, and antioxidant activity (AA) of strawberries. Experiments were performed at 20 °C, 40 °C, and 60 °C, with a constant pressure of 63 Pa in the FD chamber. The strawberry samples were cut into slices (CS) and pulped (PS) before drying. The drying kinetics was best described using the Midilli or logistic model depending on the strawberry grinding method used and the FD temperature. The FD of strawberries significantly increased the lightness, redness, and yellowness of the dried fruit. The FD temperature and pretreatment methods had little influence on the total phenolic content (TPC) and AA. The lowest TPC was found in strawberry pulps after dehydration at 60 °C, and the highest TPC was observed in strawberry slices dehydrated at the same temperature (18.54 and 22.04 mg of gallic acid equivalent per gram of dry mass, respectively). Furthermore, the ascorbic acid content in dried strawberries was higher for the samples freeze-dried at a higher temperature.

Pasta Enriched with Dried and Powdered Leek: Physicochemical Properties and Changes during Cooking

Food enrichment is commonly applied to increase the pro-health and dietary value of final products. This study aimed to evaluate how green leek powder (GL) added to semolina influenced the physicochemical, sensory, and cooking characteristics of the pasta. The pasta was prepared by partially substituting semolina with 0, 1, 2, 3, 4, and 5 g/100 g of GL. Then, the pasta samples were assessed for color, cooking properties, sensory features, mechanical properties, total phenolic content (TPC), and antioxidant activity (AA). The results indicated that GL significantly decreased the lightness and increased the yellowness of cooked pasta. The total color difference between the control pasta and enriched pasta samples ranged from 2.54 to 6.89 and 5.60 to 11.06 (for uncooked and cooked pasta, respectively). The addition of GL also caused an increase in the optimal cooking time and cooking loss. Moreover, a significant increase in stretching force was observed in cooked pasta. Sensory evaluation revealed that substitution of semolina with up to 2 g/100 g GL did not affect the smell, taste, and color of pasta. Most importantly, GL-enriched pasta was characterized by higher TPC and higher AA compared to the control samples. In summary, our results recommend partial replacement of semolina by GL (up to 3 g/100 g) in pasta production.

Value-Added Crackers Enriched with Red Onion Skin Anthocyanins Entrapped in Different Combinations of Wall Materials

The objective of this study was to encapsulate anthocyanins from red onion skins into different biopolymeric matrices as a way to develop powders with multifunctional activities. Two different variants of powders were obtained using a combination of gelation and freeze-drying techniques and characterized by encapsulation efficiency, antioxidant activity, phytochemical content, and color. Stability during storage and the bioavailability of anthocyanins in the in vitro simulated digestion were also examined. Powder V2, with a higher concentration of polysaccharides than V1, allowed a better encapsulation efficiency (90.53 ± 0.29%) and good stability during storage. Both variants had a high content of phytochemicals and antioxidant activity. In vitro investigations proved that an increased polysaccharides concentration offers the best protection for anthocyanins. Thus, a controlled release of the anthocyanins in the intestinal medium was achieved. The powder with the highest encapsulation efficiency was added to crackers, followed by phytochemical characterization to assess its potential added value. The addition of the micro-particles improved the functional characteristics such as antioxidant activity, showing its suitability for the development of bakery products. The attained results may bring implicit benefits to consumers, who can benefit from improved bioactive concentrations in foodstuffs, with significant health benefits.

Development of Functional Pizza Base Enriched with Jujube (Ziziphus jujuba) Powder

Functional and enriched foods are increasingly in demand in the global market due to their benefits for human health and their prevention of several diseases. The aim of this work was to develop a functional pizza base, produced in the Neapolitan style, exploiting the beneficial properties of jujube. The jujube fruit is rich in phenolic compounds with high antioxidant activity and represents a good candidate for functional food development. The doughs were prepared by replacing the wheat flour with 2.5%, 5.0%, and 7.5% (w/w) of Ziziphus jujube powder (ZJP) and were subsequently cooked. Chemical analyses showed that both total phenolic compounds and antioxidant activity grew with the increase of ZJP. The addition of ZJP darkened the pizza base and raised its hardness, gumminess, and chewiness. However, no difference was found in the springiness and cohesiveness of the samples with or without ZJP. These results suggest that jujube powder can be successfully introduced into pizza dough as a functional ingredient.

Effect of the Addition of Dried Dandelion Roots (Taraxacum officinale F. H. Wigg.) on Wheat Dough and Bread Properties

Dried and crushed dandelion roots (Taraxacum officinale F. H. Wigg.) (TO) were used as a formulation additive (at the amount of 0, 1, 3, 4, 5, and 6 g 100 g⁻¹ flour) to wheat bread. The farinographic properties of the dough and the physical and chemical properties of the bread were evaluated. It was found that the addition of dried flour caused a significant decrease in water absorption by the flour (1% and higher TO level), an increase in the development time (from 2% to 5% TO addition) and dough stability (3% and 4% TO level), and an increase in dough softening (4% and higher TO level). As the substitution of TO for wheat flour increased, there was a gradual decrease in loaf volume, an increase in specific weight and crumb hardness, and a darkening of the crumb color. The total polyphenol content increased linearly with the percentage increase of dried root additions TO from 0.290 to 0.394 mg GAE g⁻¹ d.m_., which translated into an increase in the antioxidant activity of the bread. It was found that dried crushed roots of Taraxacum officinale can be a recipe additive for wheat bread; however, due to their specific smell and bitter aftertaste, the level of this additive should not exceed 3 g 100 g⁻¹ flour.

Bioactive's Characterization, Biological Activities, and In Silico Studies of Red Onion (Allium cepa L.) Skin Extracts

This study aimed to investigate the thermal stability and biological activities of the phytochemicals from the red onion skins extract, which are a rich source of anthocyanins. Eight anthocyanins were identified in the extract by high-performance liquid chromatography, the most abundant ones being cyanidin 3-O-laminaribioside and cyanidin 3-O-(6″-malonoyl-laminaribioside). The study also involved the assessment of the thermal degradation kinetics of anthocyanins and antioxidant activity in the 75-155 °C temperature range. The thermal degradation kinetics was described using the first-order kinetics model. In terms of thermal stability, increasing the temperature resulted in lower half-life values (t_1/2) and higher degradation rate constant values (k) for both anthocyanins and antioxidant activity. The thermodynamic parameters revealed that the phytochemicals' degradation is a non-spontaneous and endothermic reaction. Furthermore, the inhibitory effect of the extract was investigated against the enzymes affiliated with metabolic syndrome, oxidative stress, and inflammatory process diseases. Thus, we also demonstrated that the red onion skins extract exerted inhibitory activity on α-glucosidase, α-amylase, lipase, and lipoxygenase. Considering the high content of bioactives and various biological properties, the red onion skins extract is suitable for multiple applications.

Dehydrated at Different Conditions and Powdered Leek as a Concentrate of Biologically Active Substances: Antioxidant Activity and Phenolic Compound Profile

This study aimed to analyze the antioxidant activity, phenolic acid profile, color changes, and chemical composition of dried and powdered leek (Allium porrum). Leek was divided into white shaft (WH) and green shaft (GR) and subjected to drying by different methods—convection drying, vacuum drying, and freeze-drying (FD)—at a temperature of 60 °C. A sample freeze-dried at a temperature of 20 °C was used as control. Analyses of the dried leek samples revealed that GR contained a higher amount of ash, protein, fat, fiber, phenolic acids, and flavonoids, and exhibited higher antioxidant capacity compared to WH. The dominant phenolic acid in WH was p-cumaric acid followed by synapic and protocatechuic acids. GR had a several-fold higher content of phenolic acids than WH, with ferulic acid being dominant (about 85% of the total phenolic content). It was also observed that a higher drying temperature resulted in the degradation of phenolic compounds and reduced the antioxidant properties of leek shafts. Most importantly, FD under a temperature of 60 °C caused a similar degree of degradation of biologically active compounds as air drying. An increase in drying temperature was associated with a slight decrease in the lightness of GR, whereas in the case of WH no significant change in this parameter was observed.

Physicochemical and Thermal Characteristics of Onion Skin from Fifteen Indian Cultivars for Possible Food Applications

Every year tons of onion waste is produced worldwide. The dried outer onion skin contributed up to 70% of this waste. Outer-dried skins of fifteen prominent onion cultivars from India were selected for the study. A comparative study was done for proximate profiling, thermal characteristics, functional grouping, and mineral contents. Skin of cv. “NHRDF Red” contained the highest amount of crude protein (5.97 ± 0.15 g/100 g), ash (12.24 ± 0.59 g/100 g), and fiber (8.28 ± 0.20 g/100 g), whereas cv. “Pusa Red” possessed the highest amount of total fat (0.47 ± 0.02 g/100 g) and the maximum carbohydrates (76.66 ± 0.56 g/100 g) were found in “Pusa Riddhi.” Mineral analysis showed that cv. “NHRDF Red” had the maximum concentration of all 9 minerals along with sulphur content. Fourier transform infrared spectroscopy analysis explored the various metabolites present in each cultivar. The thermal analysis explored cv. “Agrifound Dark Red” as highly thermally stable having 70.98% residual mass. The lowest Tg temperature range was found between 64.4°C and 90.6°C for “Agrifound Dark Red.” Skin of cv. “NHRDF Red” was reported as the best source of protein, fiber, and minerals, which may be utilized for developing a food product.

Dough rheology, antioxidants, textural, physicochemical characteristics, and sensory quality of pizza base enriched with onion (Allium cepa L.) skin powder

In the present research, wheat flour was replaced with onion skin powder (OSP) in 2%, 3.5%, and 5% concentration along with control to produce different pizza base variants. Prepared pizza doughs and base were investigated for different quality parameters. Rheology revealed that increased concentration of OSP elevated the storage modulus (G') (solid nature) of pizza doughs. Colour measurement of both the doughs and pizza base exhibited lightness in control (L* 86.46 ± 0.39) and darkness in 5% OSP variant (L* 46.43 ± 0.69). Physicochemical investigation showed no significant difference however, a gradual increase was obtained in fiber, water, and oil holding capacity of pizza base. Texture properties showed that the addition of OSP imparted an increased trend of hardness i.e. 5% OSP variant had maximum hardness (14.87 ± 0.20 N). A higher level of total phenols, total flavonoids, and antioxidant activity was obtained in fortified products, which exhibits onion skin as a natural source of antioxidants for functional foods. Sensory evaluation revealed OSP 2% as the most accepted variant in terms of overall acceptability. The storage study of the pizza base revealed that controlled environment was the best-suited atmosphere for a longer shelf-life of pizza base.

Effects of processing on onion skin powder added extrudates

It is possible to enhance the functional properties of extruded products with the inclusion of fruit and vegetable by-products. Onion skin, a rich source of quercetin and fiber, is considered as waste in the industry and can be used as an alternative ingredient to improve the nutritional value of the extruded products. Three levels (3, 6, and 9%) of onion skin powder (OSP) were added to wheat flour and compared with control (0% OSP). The effect of the extrusion process on accessible quercetin, total phenolic content, and antioxidant activity of the samples were investigated. In addition, carbohydrate digestibility analyses were conducted for the products. Mass spectrometry (LC-MS/MS) results indicated that increasing the OSP level increased the quercetin content. The process caused the release of the entrapped quercetin from OSP, which was revealed by significantly higher quercetin levels for the extrudates. Some of the quercetin was lost during in vitro digestion process. Increasing the OSP level increased antioxidant activity and total phenolic contents of the samples. Total phenolic contents decreased significantly after the processing, yet antioxidant activities were not affected. The extruded products showed high amounts of rapidly available glucose (69.5 g/100 g). The OSP enhancement did not change the carbohydrate digestibility of products. The results indicated that the extrusion process could increase the level of accessible bioactive ingredients, and the level of functional compound addition can be optimized further.

Sustainable Use of Fruit and Vegetable By-Products to Enhance Food Packaging Performance

Fruit and vegetable by-products are the most abundant food waste. Industrial processes such as oil, juice, wine or sugar production greatly contribute to this amount. These kinds of residues are generally thrown away in form of leftover and used as feed or composted, but they are a great source of bioactive compounds like polyphenols, vitamins or minerals. The amount of residue with potential utilization after processing has been estimated in millions of tons every year. For this reason, many researchers all around the world are making great efforts to valorize and reuse these valuable resources. Of greatest importance is the by-product potential to enhance the properties of packaging intended for food applications. Therefore, this overview collects the most recent researches dealing with fruit and vegetable by-products used to enhance physical, mechanical, antioxidant and antimicrobial properties of packaging systems. Recent advances on synthetic or bio-based films enriched with by-product components are extensively reviewed, with an emphasis on the role that by-product extracts can play in food packaging materials.

Enhanced Yield of Bioactivities from Onion (Allium cepa L.) Skin and Their Antioxidant and Anti-α-Amylase Activities

There is increasing concern for reduction of the ecological impacts of industrial waste caused by fruits and vegetables. To reduce costs of onion waste disposal while obtaining value-added products, onion skin can be used to extract quercetin, a natural flavonoid with antioxidant, anti-inflammatory and anti-cancer effects. The aim was to optimize quercetin extraction from brown onion (Allium cepa L.) skin through investigation of the effects of different parameters on quercetin yield. Operational parameters for conventional maceration extraction and for ultrasound-assisted extraction were compared: solvent type, mass-to-liquid ratio, extraction time and temperature. Antioxidant capacity was determined using DPPH· radical scavenging assays and quercetin yield using HPLC/DAD. Anti-α-amylase activity of onion skin extracts was investigated using α-amylase inhibition assays. Optimal extraction conditions of quercetin from onion skin were obtained with maceration extraction, 50% ethanol, 1:100 mass-to-liquid ratio, 25 °C, for 15 min. Under these conditions, the antioxidant capacity (expressed as quercetin equivalents) was 18.7 mg/g and the mass fraction of quercetin was 7.96 mg/g. The onion skin extracts showed a dose-dependent relationship between dry extract concentration and α-amylase inhibition, which confirms that this onion skin extract can be considered as an anti-diabetes agent.

Quantification of flavonoids, total phenols and antioxidant properties of onion skin: a comparative study of fifteen Indian cultivars

Onion waste disposal issue could be solved by using onion skin as food ingredient. Therefore, the aim of present study is the estimation of flavonoid concentration, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities of onion skin of fifteen Indian cultivars. Flavonoid quantification was achieved by high performance liquid chromatography, which showed highest concentration of quercetin, quercetin 3-β-D-glucoside, luteolin and kaempferol in cv. 'NHRDF Red' (11,885.025 mg/kg), 'Hissar-2' (1432.875 mg/kg), 'Pusa Riddhi' (1669.925 mg/kg) and 'Bhima Shakti' (709.975 mg/kg), respectively in dry weight. Highest TPC and TFC were found in cv. 'NHRDF Red' while lowest were measured in cv. 'Bhima Shubhra'. DPPH assay (%), ABTS assay (%) and FRAP assay (µmol gallic acid/g) were showed maximum antioxidant capacity for cv. 'NHRDF Red' whereas least obtained for cv. 'Bhima Shubhra'. Skin of cv. 'Hissar-2' and 'NHRDF Red' are the best source of flavonoids and natural antioxidants.

Banana Powder as an Additive to Common Wheat Pasta

This study aimed to analyse the effect of dried banana powder (BP) on common wheat pasta characteristics. Wheat flour (type 500) was replaced with 1%, 2%, 3%, 4% and 5% of BP. Control pasta without BP addition was also prepared. Pasta quality parameters including texture, colour, cooking characteristics and sensory evaluation were determined. Total phenolics content and antioxidant activity were also evaluated. The increase in BP in the pasta recipe resulted in an increase in the weight increase index (from 2.88 to 3.55) and cooking loss (from 5.2% to 6.4%). The effects of the addition of bananas were also observed in changes in colour coordinates. It was shown that BP slightly decreased the lightness of cooked pasta and had little influence on colour coordinates of raw pasta. It was also found that the addition of BP higher than 3% decreased pasta firmness. The total phenolics content and antioxidant capacity of pasta increased with the addition of BP. Sensory evaluation of pasta showed that the replacement of common wheat flour with BP should not exceed 3%.

Cytoprotective Compounds Interfere with the Nutraceutical Potential of Bread Supplemented with Green Coffee Beans

The proliferation and motile activity of prostate epithelial (Pnt2) and cancer cells (DU-145; PC-3) in the presence of bioavailable compounds from green coffee beans (GCB), wholemeal wheat bread (WMWB), and its GCB-fortified variant were analyzed. The considerable cytostatic and anti-invasive activity of GCB extracts was correlated with its phenolic contents. WMWB extract contained significantly lower levels of phenolics but still displayed relatively high cytostatic activity. However, the cytostatic properties of WMWB compounds were hardly augmented by 3% GCB flour supplementation. The cytoprotective activity of the WMWB compounds exerts a negative impact on the cytostatic activity of GCB compounds. These data confirm the relatively high chemopreventive potential of GCB. However, they also indicate that subtle interactions between bioavailable compounds in GCB and WMWB can negatively affect the nutraceutic potential of the fortified bread. Apparently, gastrointestinal processing differentially regulates the availability of individual compounds and affects the balance between the cytostatic and cytoprotective activity of the whole product. Our data show that comprehensive research is necessary before the fortification of a specific carrier with a specific supplement can be recommended.

Effects on the quality and health-enhancing properties of industrial onion waste powder on bread

Industrial onion waste powder (IOWP) was used as an additive in wheat flour at different levels: 0, 1, 2, 3, 4 and 5%. The effect of onion waste addition on the mixing properties of the dough and quality of bread was investigated. The mixing properties of the dough were determined by farinograph. The bread were characterized and evaluated for crumb hardness, crumb porosity, sensory properties, dietary fiber, total phenolic content and total flavonoids. DPPH and FRAP assays were carried out to measure antioxidant activity in vitro. The results indicated that IOWP could be used as a potential health-enhancing functional ingredient up to 3% level to produce bread enriched with dietary fiber, total phenolic compounds and total flavonoids, and characterized by high antioxidant activity and acceptable quality.

Technologies for enhancement of bioactive components and potential health benefits of cereal and cereal-based foods: Research advances and application challenges

Cereal grains are a major source of human food and their production has steadily been increased during the last several decades to meet the demand of our increasing world population. The modernized society and the expansion of the cereal food industry created a need for highly efficient processing technologies, especially flour production. Earlier scientific research efforts have led to the invention of the modern steel roller mill, and the refined flour of wheat has become a basic component in most of cereal-based foods such as breads and pastries because of the unique functionality of wheat protein. On the other hand, epidemiological studies have found that consumption of whole cereal grains was health beneficial. The health benefit of whole cereal grain is attributed to the combined effects of micronutrients, phytochemicals, and dietary fibre, which are mainly located in the outer bran layer and the germ. However, the removal of bran and germ from cereal grains during polishing and milling results in refined flour and food products with lower bioactive compounds and dietary fibre contents than those from whole grain. Also, the level of bioactive compounds in cereal food is influenced by other food preparation procedures such as baking, cooking, extrusion, and puffing. Therefore, food scientists and nutritionists are searching for strategies and processing technologies to enhance the content and bioavailability of nutrients, bioactive compounds, and dietary fibre of cereal foods. The objective of this article was to review the research advances on technologies for the enhancement of bioactive compounds and dietary fibre contents of cereal and cereal-based foods. Bioactivities or biological effects of enhanced cereal and cereal-based foods are presented. Challenges facing the application of the proposed technologies in the food industry are also discussed.

Nutritional and health-promoting properties of bean paste fortified with onion skin in the light of phenolic–food matrix interactions

The study examined the effect of fortification of bean paste with onion skin phenolics.