Antioxidant Activity of Potato Peel Extracts in a Fish-Rapeseed Oil Mixture and in Oil-in-Water Emulsions

Effect of in vitro Digestion on the Bioaccessibility of Polyphenols and Potential Prebiotic Properties of Potato Peel

BACKGROUND

Potato peel is a byproduct of the potato processing industry and a potential source of functional ingredients such as dietary fiber, polyphenols, and prebiotics. However, the bioaccessibility of polyphenols and antioxidants during in vitro digestion as well as prebiotic potential after in vitro digestion of potato peel flour has not been reported.

OBJECTIVE

The study was designed to assess the bioaccessibility of polyphenols and the prebiotic potential of potato peel flour.

METHODS

In this study, the changes in polyphenol content and antioxidant capacity during different phases of in vitro digestion, including salivary, gastric and intestinal phases were studied. Additionally, an investigation was conducted to evaluate the prebiotic properties of potato peel flour by in vitro fermentation with Lactobacillus acidophilus.

RESULTS

The findings revealed a significant increase in the recovery index for total phenolic content during both gastric (106.90%) and intestinal (102.71%) digestive phases. Furthermore, polyphenols in potato peel flour exhibited high residual intestinal digestibility index values (>90%). The antioxidant capacity increased by >50% during various phases of in vitro digestion. Regarding prebiotic properties, potato peel flour significantly increased L. acidophilus counts and promoted the production of short-chain fatty acids, specifically propionate and butyrate.

CONCLUSION

This study suggests that potato peel flour has the potential to serve as a functional ingredient or nutraceutical that can enhance health and may help in reducing environmental problems.

Agri-Food Surplus, Waste and Loss as Sustainable Biobased Ingredients: A Review

Ensuring a sustainable supply of food for the world’s fast growing population is a major challenge in today’s economy, as modern lifestyle and increasing consumer concern with maintaining a balanced and nutritious diet is an important challenge for the agricultural sector worldwide. This market niche for healthier products, especially fruits and vegetables, has increased their production, consequently resulting in increased amounts of agri-food surplus, waste, and loss (SWL) generated during crop production, transportation, storage, and processing. Although many of these materials are not utilized, negatively affecting the environmental, economic, and social segments, they are a rich source of valuable compounds that could be used for different purposes, thus preventing the losses of natural resources and boosting a circular economy. This review aimed to give insights on the efficient management of agri-food SWL, considering conventional and emerging recovery and reuse techniques. Particularly, we explored and summarized the chemical composition of three worldwide cultivated and consumed vegetables (carrots, broccoli and lettuce) and evaluate the potential of their residues as a sustainable alternative for extracting value-added ingredients for the development of new biodynamic products.

NaCl induces flocculation and lipid oxidation of soybean oil body emulsions recovered by neutral aqueous extraction

BACKGROUND

Soybean oil bodies (SOB) are naturally pre-emulsified lipid droplets recovered directly from soybean seeds. Almost all food emulsions contain salts. However, it was not clear how the incorporation of salts affected the physicochemical stability of SOB.

RESULTS

This study investigated the effect of NaCl (0-1.2%) on the physical and oxidative stability of SOB emulsions under neutral (pH 7) and acidic (pH 3) conditions. In the presence of NaCl, the SOB emulsion (pH 7) showed strong flocculation during storage due to electrostatic screening. The NaCl-induced flocculation of SOB was attenuated at pH 3, which may be due to the difference in conformation or interaction of the protein interfaces covering SOB at different pH values. The increase in ionic strength or acid conditioning treatment resulted in a remarkable increase in the stability of SOB emulsions against coalescence. The confocal laser scanning microscopy images also confirmed the NaCl-induced changes in the flocculation/coalescence properties of SOB. The oxidative behavior tests indicated that SOB emulsions containing NaCl were more susceptible to lipid oxidation but protein oxidation was inhibited due to electrostatic screening, which reduced pro-oxidant accessibility of unadsorbed proteins in the emulsion. This oxidative behavior was attenuated at pH 3.

CONCLUSION

The incorporation of NaCl significantly reduced the physical and oxidative stability of the SOB emulsion, and acidic pH mitigated NaCl-induced flocculation and lipid oxidation of SOB. © 2021 Society of Chemical Industry.

Emerging Processing Technologies for the Recovery of Valuable Bioactive Compounds from Potato Peels

Potato peel (PP) is the major underutilised by-product in the potato-processing industry and a potential source of valuable bioactive molecules. Among them, glycoalkaloids and polyphenols are important precursors for steroid hormones and natural antioxidants, respectively. Moreover, the huge quantities of industrial potato-peel waste that are produced are a rich source of primary metabolites, which principally include starch as well as non-starch polysaccharides, proteins, lipids, lignin and cellulose. All carbohydrates are prone to undergo fermentation to produce ethanol, lactic and acetic acid. Finally, the main portion of PP is made up of alcohol-insoluble matter with a dietary fibre content of approximatively 40%. The present review summarises the recent advances and emerging technologies in potato-peel extraction and further valorisation processing in the food industry.

Effects of potato peel extract on semen quality, sex hormones and immunity of rabbit bucks under intensive breeding system

This study examined the utilisation of potato peels extract (PPE), derived from potato processing, as possible antioxidants for enhancing immunity and semen quality. Twenty-four V-Line rabbit bucks 10 months old were randomly assigned into three homogenous treatments (n = 8), PPE 25 and 50 groups orally administered two different concentrations (25 and 50 mg PPE/kg body weight) every two days for four months; a control orally administered water only. Semen characteristics, serum hormones, serum immunoglobulin M and antioxidative status of seminal plasma were determined. The results reveal that treatment with both levels of PPE significantly improved sperm concentration and decreased the percentage of dead spermatozoa compared with that of the control. Seminal plasma thiobarbituric acid reactive substances significantly (p < .01) decreased with elevated levels of total antioxidant capacity, catalase, glutathione peroxidase and superoxide dismutase by PPE treatments. Serum immunoglobulin M concentration was significantly (p < .01) higher for the PPE treatments compared to the control. Our results suggest that the use of PPE could prevent the accumulation of oxidation products and may have beneficial impact on the sperm concentration. The extract lowered the percentage of dead spermatozoa by reducing the intensity of oxidation processes. Low dose of the PPE was more effective than high dose.

Evaluating the In Vitro Potential of Natural Extracts to Protect Lipids from Oxidative Damage

Lipid peroxidation is a chemical reaction known to have negative impacts on living organisms' health and on consumer products' quality and safety. Therefore, it has been the subject of extensive scientific research concerning the possibilities to reduce it, both in vivo and in nonliving organic matrices. It can be started by a variety of oxidants, by both ROS-dependent and -independent pathways, all of them reviewed in this document. Another feature of this reaction is the capacity of lipid peroxyl radicals to react with the non-oxidized lipids, propagating the reaction even in the absence of an external trigger. Due to these specificities of lipid peroxidation, regular antioxidant strategies-although being helpful in controlling oxidative triggers-are not tailored to tackle this challenge. Thus, more suited antioxidant compounds or technologies are required and sought after by researchers, either in the fields of medicine and physiology, or in product development and biotechnology. Despite the existence of several laboratory procedures associated with the study of lipid peroxidation, a methodology to perform bioprospecting of natural products to prevent lipid peroxidation (a Lipid Peroxidation Inhibitory Potential assay, LPIP) is not yet well established. In this review, a critical look into the possibility of testing the capacity of natural products to inhibit lipid peroxidation is presented. In vitro systems used to peroxidize a lipid sample are also reviewed on the basis of lipid substrate origin, and, for each of them, procedural insights, oxidation initiation strategies, and lipid peroxidation extent monitoring are discussed.

Utilization of potato peel as eco-friendly products: A review

An eco-friendly product has been the primary agenda of twenty-first century of the global scientists. One of the main focuses is by-product recycling of food processing industries. It has been long time since food industry byproduct converted into energy and value added products. Potato processing is newly emerging food processing factories in developing countries, and potato is the fourth important crop globally. A dramatic food demand increment had shown in the past two decades. This leads to increase the number of food processing industries. Nowadays, food processing industries particularly processed potato manufactures are expanding and generate a huge volume of potato peel. This by-product causes environmental pollution due to decomposition. However, food byproducts like potato peel have essential organic matter. So this review introduces the potential use of potato peel as food preservative, pharmaceutical ingredient, renewable energy, and animal feed to promote eco-friendly food industries.

Establishment of ultrasound-assisted extraction of phenolic compounds from industrial potato by-products using response surface methodology

Potato processing generates large amounts of by-products, which include potato peels and the outer layers of flesh, which contain phenolic compounds. The purpose of this study was to establish an extraction method for phenolic compounds from industrial potato by-products by using response surface methodology (RSM). Box-Behnken design (BBD) was performed to optimize the extraction conditions of phenolic compounds considering different extraction temperature, ratios of ethanol/water, time of extraction and sample/solvent ratio. The optimum extraction conditions were obtained with ethanol/water 55/45 (v/v) by ultrasound bath during 35 min at 35 °C and 1/10 sample/solvent ratio. The best conditions were applied to determine the phenolic content in five potato by-products. The analyses by HPLC-DAD-ESI-MS showed that chlorogenic acid accounted for a 49.3-61% of the total phenolic compounds. Positive Pearson correlations between HPLC data and antioxidant activity confirmed that the phenolic compounds had significant antioxidant properties.

Synthesis of novel octyl sinapate to enhance antioxidant capacity of rapeseed-linseed oil mixture

BACKGROUND

Lipophilisation allows the formation of new functionalised antioxidants having beneficial properties compared to natural hydrophilic phenolic acids. Therefore, this work focused on the synthesis of lipophilic antioxidants, such as a new octyl sinapate, octyl caffeate and octyl ferulate using the modified Fischer esterification of selected hydroxycinnamic acids with 1-octanol.

RESULTS

The lipophilic octyl sinapate was obtained for the first time with satisfactory yield (83%) after purification by column chromatography. The identity of the synthesised phenolipids was confirmed by chromatographic and spectroscopic analyses. Antioxidant capacity of phenolipids was determined by DPPH (IC₅₀  = 35.87-52.24 μg mL^-1 ) and ABTS (IC₅₀  = 39.45-48.72 μg mL^-1 ) methods and compared with IC₅₀ values (7.37-35.30 μg mL^-1 and 7.55-41.67 μg mL^-1 , respectively) for well known antioxidants. The antioxidant capacity of rapeseed-linseed oil enriched with the purified esters was about two to 30 times higher in comparison with a non-supplemented oil.

CONCLUSION

The novel octyl sinapate as well as octyl caffeate and octyl ferulate have antioxidant properties and lipophilic character, therefore they may be added to vegetable oils as potential antioxidants for tackling oxidative processes. © 2017 Society of Chemical Industry.

Evaluation of antioxidant potential of essential oils of some commonly used Indian spices in in vitro models and in food supplements enriched with omega-6 and omega-3 fatty acids

The aim of this study was to evaluate and compare the antioxidant potential of essential oils of some commonly used Indian spices (black pepper, cinnamon, clove, coriander and cumin) in various in vitro models and in food supplements enriched with omega-6 and omega-3 fatty acids. In vitro antioxidant potential was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and Fe²⁺ ion-chelating methods and lipid oxidation stabilisation potential was evaluated in bulk soybean oil-fish oil mixture and their oil-in-water emulsions using peroxide value (PV), p-anisidine value (p-AV) and total oxidation value as indicators of oxidation. Combination effects using DPPH radical scavenging and Briggs-Rauscher oscillating reaction methods were also evaluated. Test essential oils showed varying degrees of radical scavenging and Fe²⁺ ion-chelating efficacy. Clove and coriander oils showed significantly higher (P < 0.05) radical scavenging and Fe²⁺ ion-chelating potential over other tested essential oils as well as BHT and ∞-tocopherol. The anti-lipid peroxidative potential of test essential oils was found in the following decreasing order: clove > coriander > BHT > cinnamon > α-tocopherol > cumin > black pepper. Furthermore, clove and coriander oils showed synergistic antioxidant activity in combination both in DPPH radical scavenging and Briggs-Rauscher oscillating reaction methods whereas other possible combinations showed additive effects. Strong radical scavenging and Fe²⁺-chelating as well as anti-lipid peroxidative activities of clove and coriander oils provide evidence that clove and coriander oils may serve as a potential source of natural antioxidants for retarding lipid oxidation of food supplements enriched with omega-6 and omega-3 fatty acids.

The enhancement of pistachio green hull extract functionality via nanoliposomal formulation: studying in soybean oil

Phenolic compounds of pistachio green hull extract (PGHE) were incorporated into nanoliposomes (NLs). The NLs were prepared with different concentrations of phenolic compounds of PGHE (500, 750 and 1000 ppm) and particle size, polydispersity index (PDI), zeta potential and encapsulation efficiency (EE) were investigated. The antioxidant activity of free and incorporated phenolic compounds of PGHE were evaluated in soybean oil during 39 days of storage by measuring peroxide (PV), thiobarbituric acid (TBA) values and color. The total phenolic content and IC₅₀ (DPPH assay) of PGHE were 614.91 ± 0.45 mg gallic acid equivalent/g fresh weight of extract and 10 ± 0.05 μg/ml extract, respectively. The prepared NLs had 101.86-105.81 nm size and PDI = 0.202-0.235. The zeta potential value of NLs varied between -47.7 and -52.3 mV. The highest EE (32.47%) was observed for NLs containing 1000 ppm of phenolic compounds. The lowest PV and TBA values were related to free phenolic compounds at 500 mg/kg oil. In comparison with free phenolic compounds, loaded NLs had lower antioxidant activity, but encapsulation could improve the stability, gradual release and solubility of phenolic compounds in soybean oil. The color of NLs containing oil samples remained constant during the storage, but free phenolic compounds changed the oil`s color. All concentrations of free and incorporated phenolic compounds had also higher antioxidant activity than BHT. Finally, 500 ppm of phenolic compounds of PGHE in its incorporated forms could be recommended as a substitute for synthetic antioxidant in soybean oil.

Synthesis, characterization, solubilization, cytotoxicity and antioxidant activity of aminomethylated dihydroquercetin

A dihydroquercetin derivative (DHQA) was prepared through aminomethylation to overcome the low water solubility and bioavailability of dihydroquercetin (DHQ). DHQA was characterized through HPLC, nuclear magnetic resonance, scanning electron microscopy, X-ray diffraction, and thermogravimetric analyses. DHQA was converted into the amorphous form, but the major structure of DHQ remained unchanged. Solubilization and dissolution tests were also performed. Results showed that the solubility and dissolution rates of DHQA were approximately 16.28 and 6.31 times higher than those of DHQ, respectively. The MTT assay of DHQA showed a non-toxic effect against non-cancerous HEK-293T cells (EC₅₀ = 820.00 μM), and potent inhibitory activity against cancerous Hela cells (EC₅₀ = 138.17 μM). Finally, the antioxidant activity of DHQA was confirmed in vitro through DPPH and ABTS radical scavenging activity assays. DHQA displayed high antioxidant activities with low IC₅₀ values (0.043 and 0.042 mM, respectively). Reducing Fe³⁺ power assay indicated that DHQA exhibited higher reducing power than DHQ and ascorbic acid.

Health-beneficial properties of potato and compounds of interest

Potatoes have shown promising health-promoting properties in human cell culture, experimental animal and human clinical studies, including antioxidant, hypocholesterolemic, anti-inflammatory, antiobesity, anticancer and antidiabetic effects. Compounds present such as phenolics, fiber, starch and proteins as well as compounds considered antinutritional such as glycoalkaloids, lectins and proteinase inhibitors are believed to contribute to the health benefits of potatoes. However, epidemiological studies exploring the role of potatoes in human health have been inconclusive. Some studies support a protective effect of potato consumption in weight management and diabetes, while other studies demonstrate no effect and a few suggest a negative effect. As there are many biological activities attributed to the compounds present in potato, some of which could be beneficial or detrimental depending on specific circumstances, a long-term study investigating the association between potato consumption and diabetes, obesity, cardiovascular disease and cancer while controlling for fat intake is needed. © 2016 Society of Chemical Industry.

Characterization and Antioxidant Activity of Flash-Assisted Extracted Dihydroquercetin from Wood Sawdust of Larix gmelinii Using a Response Surface Methodology

We investigate a flash-assisted extraction of dihydroquercetin (DHQ) from wood sawdust of Larix gmelinii by response surface methodology. Box–Behnken design optimized the extraction conditions, and the highest DHQ yield (6.15 %) was obtained under optimal extraction conditions: FAE time (3 min), extraction time (3 h), solid-to-liquid (g/mL) ratio (1:15), and ethanol concentration (75 %). After purification, the DHQ purity was 96 % as determined by HPLC and was further characterized by FTIR. Purified DHQ’s antioxidant activities were confirmed in vitro by determining DPPH and ABTS radical scavenging activities and reducing Fe3+ power. In the DPPH and ABTS radical scavenging activity assays, DHQ displayed prominent antioxidant activities with low IC50 values (11.568 and 12.475 μg/mL, respectively). In reducing Fe3+ power assay, high DHQ absorbance values showed that DHQ had higher reducing power than butylated hydroxyl toluene and had nearly the same consistent power as ascorbic acid at the same doses.

Phenolic Compounds in the Potato and Its Byproducts: An Overview

The potato (Solanum tuberosum L.) is a tuber that is largely used for food and is a source of different bioactive compounds such as starch, dietary fiber, amino acids, minerals, vitamins, and phenolic compounds. Phenolic compounds are synthetized by the potato plant as a protection response from bacteria, fungi, viruses, and insects. Several works showed that these potato compounds exhibited health-promoting effects in humans. However, the use of the potato in the food industry submits this vegetable to different processes that can alter the phenolic content. Moreover, many of these compounds with high bioactivity are located in the potato's skin, and so are eliminated as waste. In this review the most recent articles dealing with phenolic compounds in the potato and potato byproducts, along with the effects of harvesting, post-harvest, and technological processes, have been reviewed. Briefly, the phenolic composition, main extraction, and determination methods have been described. In addition, the "alternative" food uses and healthy properties of potato phenolic compounds have been addressed.

Phenolic compounds and antioxidant activities of selected species of seaweeds from Danish coast

Water and ethanolic extracts of 16 species of seaweeds collected along the Danish coasts were screened for antioxidant activities using four in vitro antioxidant assays (2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, reducing power, ferrous ion-chelating and liposome model system). Furthermore their effectiveness in retarding lipid peroxidation in fish oil was evaluated by an accelerated stability test. Significant differences were observed in total and individual phenolic content and the antioxidant activities of seaweed species evaluated. Ethanol was more efficient for polyphenol extraction than water. Polysiphonia fucoides and all the Fucus species tested showed highest radical scavenging activity, reducing power, inhibition of oxidation in liposome model system and in fish oil and were high in phenolic content. These seaweeds could be potential rich sources of natural antioxidants for protection of foods against oxidation. In general, the various antioxidative assays correlated well with the total phenolic content, indicating that algal polyphenols are active components in these extracts. However, in some of the antioxidative assays some species with low total phenolic content also showed good antioxidative effects indicating that some other co-extracted active compounds such as pigments and tocopherols in ethanolic extracts and sulphated polysaccharides, proteins or peptides in water extracts may also contribute to the overall antioxidant properties and this needs further investigation.

Antioxidant ability of fractionated apple peel phenolics to inhibit fish oil oxidation

Polyphenols isolated from frozen and dried apple peels were studied as potential natural antioxidants to stabilize omega-3 polyunsaturated fatty acid (ω3 PUFA) enriched fish oil. The ethanolic extracts of apple peels were fractionated by reversed phase chromatography using gradient elution of 20-100% aqueous ethanol. The collected fractions were analyzed by ultra pressure liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The total phenolic content and antioxidant capacity of each fraction were evaluated by Folin-Ciocalteu (FC), ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging assays. Inhibition of fish oil oxidation was studied using the thiobarbituric acid reactive substances (TBARS) assay. Polyphenols fractionated using frozen apple peel extract had significantly higher FC, FRAP and DPPH(·) scavenging values than those of dried apple peel (p<0.05). The flavonol-rich fractions inhibited fish oil oxidation by 40-62% at a total phenolic concentration of 200 μg/ml. The fractionated polyphenols from both dried and frozen apple peel showed higher inhibition of lipid oxidation compared to α-tocopherol, butylated hydroxytoluene and crude apple peel extracts.

Solvent extraction of antioxidants from steam exploded sugarcane bagasse and enzymatic convertibility of the solid fraction

Solvent extraction of steam exploded lignocellulosic biomass may be a potential way to obtain antioxidative extracts and to enhance the enzymatic convertibility of the solid residue. Boiling solvent extraction (BSE) showed higher solid and phenolic yields than room temperature extraction. Solubilities of phenolics and sugars were higher in anhydrous ethanol (AE) and deionized water (DW) than in ethyl acetate under each individual extraction condition. The antioxidant activities of the AE and DW extract obtained under BSE were better than those of 10mM vitamin C. Conversion of the solid fractions into reducing sugar using Celluclast 1.5L and Novozym 188 after AE and DW extraction was 95.13% and 92.97%, respectively, higher than that obtained with SESB (88.95%).