Search Results (44)

Mercury (Hg) exposure is a major environmental risk factor, closely linked to oxidative stress and cardiovascular disease. Red blood cells (RBC), due to their high oxygen exposure and lack of repair mechanisms, are particularly sensitive to oxidative injury and are key indicators of systemic redox imbalance. This study evaluates the protective effects of polyphenolic extracts from Annurca apple, specifically flesh and peel, from both ripe and unripe fruit, on HgCl₂-exposed human RBCs. Key oxidative stress markers were measured, including ROS production, GSH levels, lipid peroxidation (TBARS), MetHb formation, SH group content, microvesicle (MV) generation, and morphological changes. Peel extracts, particularly those from ripe apples, consistently exhibited stronger antioxidant and cytoprotective effects than flesh extracts, effectively reversing Hg-induced oxidative damage and preserving RBC integrity. Notably, these extracts restored redox homeostasis and GSH levels, reduced ROS and TBARS accumulation, prevented MetHb formation, and mitigated MV release and morphological alterations. These protective effects appear to involve multifactorial mechanisms. These findings highlight the nutraceutical potential of Annurca apple extracts in counteracting heavy metal-induced oxidative stress and support their possible relevance for future studies aimed at health protection and waste valorization. Full article

This study explores the sustainable valorization of Annurca apple by-products by examining the polyphenolic content and antioxidant activity of peel, flesh, and core at two ripening stages. Ripening significantly enhanced the concentration of bioactive compounds, particularly in the peel, where total polyphenols increased from 124.4 to 423.3 mg of CAE/100 g FW, flavonoids from 18.2 to 51.3 mg of quercetin equivalents, and ortho-diphenols from 11.9 to 36.1 mg of CAE. The flesh and core showed more moderate increases. Antioxidant activity, assessed using five in vitro assays (DPPH, ABTS, FRAP, TAC, and H₂O₂), was consistently highest in the peel, especially in the ABTS assay. Although the flesh had fewer phenolics, it showed a 1.5-fold increase during ripening, accompanied by improved antioxidant performance. The core also proved notable antioxidant potential, particularly in ripe samples. UHPLC-MS/MS analysis identified 11 phenolic compounds, showing tissue- and ripening-specific distribution. SDS-PAGE revealed a ripening-related increase in Thaumatin-like Protein 1a (TLP1a), especially in the core and flesh. Its association with tissues showing high antioxidant ability suggests a possible role in enhancing the bioactivity of polyphenol-rich extracts. From an agri-food waste valorization perspective, the peel and core represent promising sources of bioactive compounds for developing functional foods and nutraceuticals. Full article

The circular economy approach offers innovative solutions for valorizing apple by-products through biofortification strategies transforming waste into high-value products and reducing environmental impact. This study evaluates innovative solutions for valorizing Granny Smith apple peel (RM) through biofortification in phenolic compounds using individual or combined abiotic stresses, like wounding stress and ultraviolet A (UVA) radiation. The effects of cutting type (Ct) [whole (C1), 5 mm (C2), 1.5 mm (C3)], storage temperature (ST) [20, 15, 10, 5 °C], and storage time (TM) [0, 12, 24, 48, 72 h] on phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) activity, total phenolic content (TPC), and phenolic profiles were studied first. The results show that higher stress intensity (C3, 15 °C, 48 h) significantly enhanced secondary metabolism, leading to notable increases in PAL activity (1201%), PPO activity (308%), TPC levels (108–118%), and Procyanidin B2 (PACB2, 22%), the predominant phenolic compound. These changes were critical for improving the bioactive properties and antioxidant potential of RM. The second assay combined wounding stress (same levels of Ct and ST of previous assay, TM: 56 h) with UVA radiation (UVA-D) [0, 86.4 KJ m⁻², 172.8 KJ m⁻²], determining the optimal conditions (C3, UVA-D 66 KJ m⁻², 17 °C) for maximizing PAL activity (0.12–0.20 ΔA h⁻¹ mg⁻¹), and TPC (3.3 g GAE kg⁻¹). This study demonstrates the potential of combined abiotic stresses as cost-effective scalable tools to biofortify RM, promoting the sustainable and value-added utilization of agro-industrial by-products. Full article

Apple by-products (i.e., peels) are often thrown away, yet they are highly nutritious and provide numerous advantages as they contain a variety of nutrients such as vitamins, minerals, and antioxidants. Apple peels also comprise a high level of antioxidants, particularly polyphenols and flavonoids. This research aimed to determine the most efficacious extraction techniques and parameters to accomplish maximum bioactive compounds recovery from apple peels. Several extractions were conducted, including stirring, ultrasonication, and pulsed electric field-assisted extractions. Response surface methodology and several factors such as temperature, extraction duration, and solvent composition were considered to have a major impact on the isolation of bioactive compounds. The findings indicated that the most practical and efficient approach was to combine the pulsed electric field process with ultrasonication and stirring at 80 °C for 30 min, while 75% aqueous ethanol comprised the optimal solvent concentration, demonstrating the critical role of the solvent in optimizing extraction efficiency. The optimal conditions were obtained through response surface methodology with a statistical significance of p < 0.05. The extract exhibited a total polyphenolic content (TPC) of 17.23 mg gallic acid equivalents (GAE) per g of dry weight (dw), an ascorbic acid content (AAC) of 3.99 mg/g dw, and antioxidant activity of 130.87 μmol ascorbic acid equivalents (AAE)/g dw, as determined by FRAP and 95.38 μmol AAE/g dw from the DPPH assay. The measured antioxidant activity highlighted the significant potential of apple peels as a cost-effective source of exceptionally potent extracts. Full article

Polyphenols are important functional components that have anti-cancer and anti-inflammatory effects. Apple fruit is rich in polyphenols and is one of the dietary sources of polyphenols. The polyphenol components and contents of the peel and pulp of 74 Malus sieversii (Led.) Roem. and 26 Chinese Malus germplasm resources were determined using ultra-high-phase chromatography (UPLC) and liquid chromatography–mass spectrometry (LC–MS). The results showed that 34 components were detected in the peel and 30 in the flesh, and that the polyphenol components and contents of the different germplasm resources were significantly different; the polyphenol content of Malus sieversii (Led.) Roem. was significantly higher than that of the other local varieties, and the polyphenol content in the peel was also higher than that in the flesh. Rutin, quercetin 3-O-arabopyranoside, kaempferol 3-O-rutinoside, and peonidin 3-O-galactoside were detected only in the peel. The total polyphenol content in the peel ranged from 949.76 to 5840.06 mg/kg, and the polyphenol content in the pulp ranged from 367.31 to 5123.10 mg/kg. The cluster analysis of polyphenol components and contents in peel and pulp showed that 100 Malus germplasm resources could be grouped into four categories. Principal component analysis of 34 kinds and 30 kinds of polyphenols in peel and pulp of 100 resources was performed. If the eigenvalue is greater than 1, eight and seven principal components are extracted, respectively. Five Malus resources with high polyphenol content in the peel and pulp were selected: ‘XY-77’ (peel: 5840.06 mg/kg, pulp: 5123.10 mg/kg; ‘LF-09’ (peel: 4692.63 mg/kg, pulp: 3729.79 mg/kg); ‘2012-5’ (peel: 4377.61 mg/kg, pulp: 3847.54 mg/kg); ‘29028’ (peel: 5088.05 mg/kg, pulp: 3994.61 mg/kg); and ‘11-01’ (peel: 5154.45 mg/kg, pulp: 3616.15 mg/kg). These results provide us with information regarding the polyphenol composition and content of the wild apple resources and local cultivars. The high polyphenol content resources obtained by screening can be used as raw materials for the extraction of polyphenol components and functional fruit juice processing and can also be used as parents for functional fruit creation and variety breeding. Full article

In this study, fruits of the red flesh Malus plant ‘Hongxun 2’ (Malus neidzwetzkyana (Dieck) Langenf.) and green flesh Malus plant ‘Xinye 13-11’ (Malus sieversii (Led.) Roem.) were used as experimental materials. Both of them came from Xinjiang, China, and Malus neidzwetzkyana (Dieck) Langenf. is believed to be a variant of Malus sieversii (Led.) Roem. The components and contents of polyphenols in the peel and pulp of the two kinds of fruit during the development period were detected, and the dynamic changes and differences in the polyphenols between the two kinds of fruit were discussed. The results showed that the total polyphenol content of ‘Xinye 13-11’ was higher in the peel and pulp than that of ‘Hongxun 2’, and the content of peel was higher than that of pulp in the two kinds of fruit. An analysis of five types of polyphenols showed that anthocyanins were only contained in the peel and pulp of ‘Hongxun-2’, and the peel had a higher content than the pulp. Cyanidin 3-O-galactoside was the main anthocyanin component. Four other types of substances, except hydroxycinnamics, were higher in ‘Hongxun-2’ than ‘Xinye 13-11’, while the contents of other substances in ‘Xinye 13-11’ were higher than those of ‘Hongxun 2’. The accumulation of major polyphenol components in the peel and flesh of ‘Hongxun 2’ and ‘Xinye 13-11’ apples was significant in the period before and after 65 days after flowering, and the contents of procyanidin B1 and procyanidin C1 were the highest in this period. In addition to the difference in anthocyanin content between ‘Hongxun 2’ and ‘Xinye 13-11’, the chlorogenic acid content in the peel and pulp of ‘Hongxun 2’ was significantly higher than that of ‘Xinye 13-11’, and the contents of other components were lower than those of ‘Xinye 13-11’. Moreover, based on the components and contents of polyphenol components, this paper supports the viewpoint that Malus neidzwetzkyana (Dieck) Langenf is a separate species to Malus sieversii (Led.) Roem. Full article

The cider-making industry in Asturias generates between 9000 and 12,000 tons of apple pomace per year. This by-product, the remains of the apple pressing, and made up of peel, flesh, seeds and stems, is a valuable material, containing substantial amounts of antioxidant compounds associated with healthy properties. Polyphenols such as dihydrochalcones and quercetin glycosides, and triterpenic acids, among which ursolic acid is a major compound, are the main antioxidant families described in apple pomace. The simultaneous recovery of those families has been accomplished by low frequency ultrasound-assisted extraction. Working extraction conditions were optimised by response surface methodology (RSM): time, 5.1 min; extractant composition, 68% ethanol in water; solid/liquid ratio, 1/75 and ultrasonic wave amplitude, 90%. This procedure was further applied to analyse those components in the whole apple pomace (WAP), apple peel (AP) and apple flesh (AF). On average, dry WAP contained almost 1300 µg/g of flavonols, 1200 µg/g of dihydrochalcones and 4200 µg/g of ursolic acid. These figures increased in the apple peel to, respectively 2500, 1400 and 8500 µg/g dry matter. Two linear multivariate regression models allowed the antioxidant activity of apple by-products to be predicted on the basis of their bioactive composition. The results derived from this study confirm the potential of industrial cider apple pomace as a source of high-value bioactive compounds, and the feasibility of the ultrasound-assisted extraction technique to recover those components in a simple and efficient way. Full article

This study investigates agro-industrial by-products as sources of bioactive compounds, particularly focusing on phenolic compounds known for their antioxidant properties. With growing interest in natural alternatives to synthetic antioxidants due to safety concerns, this study highlights the health benefits of plant-derived phenolic compounds in food preservation and healthcare products. Traditional and advanced analytical techniques were used to obtain phytochemical profiles of various residue extracts, including espresso (SCG) and cold-brew spent coffee grounds (CBCG), pineapple peel (PP), beetroot pomace (BP), apple pomace (AP), black carrot pomace (BCP), and garlic peel (GP). Assessments of total phenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity (AC) supported their revalorization. CBCG showed the highest TPC, TFC, and AC. TPC content in by-products decreased in the order CBCG > SCG > GP > BCP > PP > AP > BP, with a similar trend for TFC and AC. Phytochemical profiling via FI-ESI-FTICR-MS enabled the preliminary putative identification of a range of compounds, with polyphenols and terpenes being the most abundant. Univariate and multivariate analyses revealed key patterns among samples. Strong positive correlations (Pearson’s R > 0.8) indicated significant contribution of polyphenols to antioxidant capacities. These findings highlight the potential of agro-industrial residues as natural antioxidants, advocating for their sustainable utilization. Full article

Background: Alkaloid- and polyphenol-rich white mulberry leaf and apple peel extracts have been shown to have potential glucose-lowering effects, benefitting the control of postprandial blood glucose levels. This study aimed to determine the effect of the combination of Malus domestica peel and Morus alba leaf extracts (GLUBLOC^TM) on postprandial blood glucose and insulin-lowering effects in healthy adults after a carbohydrate-rich meal or sucrose drink intake. Methods: This study was designed as a randomized, crossover, single-blinded clinical trial. Out of 116 healthy participants, 85 subjects (aged 18–60 years) completed the day 1 and 5 crossover study. On day 1, subjects were supplemented with a placebo or GLUBLOC^TM tablet 10 min before the carbohydrate-rich meal (300 g of tomato rice) or sucrose drink intake (75 g of sucrose dissolved in 300 mL water). On day 5, the treatments were crossed over, and the same diet was followed. Postprandial blood glucose and insulin levels were measured on days 1 and 5 (baseline 0, post-meal 30, 60, 90, and 120 min). Differences in iAUC, Cmax, and Tmax were determined between the placebo and GLUBLOC^TM-treated cohorts. Results: Significant changes in total iAUC (0–120 min), Cmax, and Tmax of postprandial blood glucose and insulin levels were noticed upon GLUBLOC^TM supplementation. The percentage reduction in the iAUC of blood glucose levels was 49.78% (iAUC_0–60min) and 43.36% (iAUC_0–120min), respectively, compared with the placebo in the sucrose drink intake study. Similarly, there was a 41.13% (iAUC_0–60min) and 20.26% (iAUC_0–120min) glucose-lowering effect compared with the placebo in the carbohydrate-rich meal intake study. Conclusions: Premeal supplementation with GLUBLOC^TM significantly reduced the postprandial surge in blood glucose and insulin levels after a carbohydrate-rich meal or sucrose drink intake over 120 min in healthy individuals. This study proves that GLUBLOC^TM can manage steady postprandial blood glucose levels. Full article

Supercritical fluid extraction (SFE) was used to extract bioactive compounds from apple (Malus domestica) peel waste from three different Italian cultivars. The bioactive fractions were extracted applying a temperature of 60 °C and a pressure of 250 bar for 15 min with 20% ethanol as co-solvent, at a flow rate of 2 mL/min. The total polyphenol (TP), anthocyanin (TA), ascorbic acid (AA), and antioxidant activity contents (TACs) were measured, while chromatographic analyses were performed to highlight the differences between the extracts. The Stark cultivar had the highest levels of polyphenols, anthocyanins, and ascorbic acid, while the Royal Gala cultivar showed the highest total antioxidant activity. SFE extracts were then tested for their effect on the mitochondrial NADH–ubiquinone oxidoreductase (Complex I) activity on mitochondria isolated from human embryonic kidney cells (HEK239). The Stark extract showed the most positive response in terms of NADH oxidation. The results obtained in this work highlight the potential of apple peel waste as a source of functional phytocompounds and suggest that Stark cultivar extracts may be exploited for pharmacological applications. This study supports the circular bioeconomy by promoting the use of waste products as a valuable resource. Full article

The aim of this study is to assess the storability and nutritional value of new Polish apple cultivars recommended for cultivation after storage under low-oxygen atmospheric conditions (ULO and DCA). Fruit characteristics of ‘Chopin’ and clone ‘JB’ were evaluated in relation to commonly grown apple cultivars. Fruits of six selected apple cultivars were stored for a period of 9 months in conventional (0.04% CO₂: 21% O₂), Ultra-Low Oxygen (1.5% CO₂: 1.5% O₂), and Dynamic Controlled Atmosphere (0.6% CO₂: 0.6% O₂) cold storage. Physicochemical characteristics of the apples (firmness, soluble solids, acidity, and fibre content), nutritional and antioxidant values of the fruit (P, K, Ca, Mg, Fe, Cu, Zn, total polyphenols, total flavonoids, and antioxidant capacity), and safety of consumption (residues of pesticides) were assessed. The new cultivar ‘Chopin’ and clone ‘JB’ were characterised by above-average acidity and clone ‘JB’ stood out in terms of antioxidant properties. Storage in a low-oxygen atmosphere in DCA was more effective in limiting fruit ripening than conventional cold storage, contributing to the preservation of the high potential of biologically active compounds in the apples. Apples after 9 months of storage were characterised by higher firmness (from 3.5 to 14 N), higher total polyphenol content in the flesh (from 8 to 23 mg∙100 g⁻¹ FW) and peel (from 32 to 97 mg∙100 g⁻¹ FW), as well as higher antioxidant capacity in the flesh (from 15 to 37 mg AAE∙100 g⁻¹ FW) and peel (from 28 to 59 mg AAE∙100 g⁻¹ FW) when stored in DCA compared to cold storage. Full article

Freeze-dried apple peel powder (Fd-APP) was subjected to in vitro digestion and colonic fermentation to evaluate the variations in its phenolic composition, bioactivities (antioxidant activity, α-amylase, and α-glucosidase inhibition), and fecal metabolic outputs. A total of 88 phenolics were tentatively identified, of which 51 phenolic compounds were quantitated in Fd-APP sample extracts before digestion, and 34 were released during subsequent phases of digestion. Among these, phenolic acids showed the highest bio accessibility index (BI) of 68%, followed by flavonoids (63%) and anthocyanins (52%). The inhibitory functions of Fd-APP extract against α-amylase and α-glucosidase pre- and post-digestion were moderate and ranged from 41.88 to 44.08% and 35.23 to 41.13%, respectively. Additionally, the antioxidant activities revealed a significant (p ≤ 0.05) decline during the in vitro digestion. However, the colonic fermentation stage presented different products where the intact parent phenolic compounds present in Fd-APP were utilized by gut microbes and produced various phenolic metabolites such as 3- hydroxyphenyl acetic acid (3-HPAA), ferulic acid (FA), 3-(4-hydroxyphenyl) propionic acid (3,4 HPPA) and 4- hydroxybenzoic acid (4-HBA). Furthermore, colonic fermentation of Fd-APP accelerated the production of short-chain fatty acids (SCFAs), with acetic acid being the most prevalent (97.53 ± 9.09 mM). The decrease in pH of fermentation media to 4.3 significantly (p ≤ 0.05) enhanced counts of Bifidobacterium (10.27 log CFU/mL), which demonstrated the potential prebiotic effects of Fd-APP. These findings indicated that the consumption of apple peel as a constituent of novel functional foods may support and protect the intestinal microbiota and consequently promote human health. Full article

Apple pomace (AP) from the food industry is a mixture of different fractions containing bioactive polyphenolic compounds. This study provides a systematic approach toward the recovery and evaluation of the physiochemical and biological properties of polyphenolic compounds from AP. We studied subcritical water extraction (SCW) and solvent extraction with ethanol from four different AP fractions of pulp, peel, seed, core, and stem (A), peel (B), seed and core (C), and pulp and peel (D). The subcritical water method at the optimum condition resulted in total polyphenolic compounds (TPC) of 39.08 ± 1.10 mg GAE per g of AP on a dry basis compared to the ethanol extraction with TPC content of 10.78 ± 0.94 mg GAE/g db. Phloridzin, chlorogenic acid, and quercetin were the main identified polyphenolics in the AP fractions using HPLC. DPPH radical scavenging activity of fraction B and subcritical water (SW) extracts showed comparable activity to ascorbic acid while all ethanolic extracts were cytocompatible toward human fibroblast (3T3-L1) and salivary gland acinar cells (NS-SV-AC). Our results indicated that AP is a rich source of polyphenolics with the potential for biomedical applications. Full article

The present research was undertaken to investigate polyphenolic profiles of peel, pulp and juices made from two standard commercial and five traditional apple cultivars from Bosnia and Herzegovina. The main goal of the study was to monitor the distribution and changes of polyphenolic profiles through different phases of apples’ processing into cloudy and clear juices, with regard to L-ascorbic acid pretreatment. Quantitative determination of phenolic compounds was carried out by using high-performance liquid chromatography with diode-array detection. The obtained results showed that traditional cultivars, namely ‘Paradija’ and ‘Prijedorska zelenika’, displayed significantly higher content of these compounds compared to commercial ones. Flavan 3-ols and flavonol glycosides were mostly found in peels of all cultivars (21.2–44.1 and 5.40–33.3%, respectively), while phenolic acids along with flavan 3-ols were predominant in the pulp (8.20–30.8 and 5.10–13.9%, respectively). Apples’ processing into juices caused decrease (more than 90%) in the content of all polyphenols and the distribution of these compounds from fruits to final products had a negative trend, particularly evident in clear juices. The most drastic loss occurred in the flavonol glycosides and dihydrochalcones content, while chlorogenic acid displayed quite stable distribution from apples to final products due to its good solubility. Apple mash pretreatment with L-ascorbic acid had a positive impact on the preservation and retention of polyphenols. Full article

The aim of the study was to describe the physicochemical properties, with particular emphasis on nutritional value, of apples ‘Chopin’ and clone ‘JB’. The new cultivars were compared with the cultivars commonly cultivated in Polish orchards, namely ‘Gala Brookfield’, ‘Šampion’, ‘Ligol’ and ‘Idared’. The study focuses on the evaluation of physicochemical characteristic (firmness, soluble solids content and titratable acidity) and the content of monosaccharides, sucrose and organic acids based on HPLC with an RI detector. In addition, the nutritional value of apples were described separately for the flesh and peel of the fruit, focusing on the assessment of the antioxidant activity and the content of total polyphenols, phenolic acids, flavonols using the HPLC technique. ‘Chopin’ and ‘JB’ clone apples are characterized by very high acidity, over 1%, which is related to the high content of malic acid. The red flesh ‘JB’ clone is characterized by a high content of bioactive compounds in both the peel and flesh of apples. High temperatures and a lack of precipitation contribute to a higher polyphenol content in apples, which proves that apart from the genetic features of the cultivars, the climatic conditions also determine the nutritional value of the fruit. Full article