Health Benefits of Apple Juice Consumption: A Review of Interventional Trials on Humans

Effect of UV LED and Pulsed Light Treatments on Polyphenol Oxidase Activity and Escherichia coli Inactivation in Apple Juice

Enzymatic browning in fruits and vegetables, driven by polyphenol oxidase (PPO) activity, results in color changes and loss of bioactive compounds. Emerging technologies are being explored to prevent this browning and ensure microbial safety in foods. This study assessed the effectiveness of pulsed light (PL) and ultraviolet light-emitting diodes (UV-LED) in inhibiting PPO and inactivating Escherichia coli ATTC 25922 in fresh apple juice (Malus domestica var. Red Delicious). Both treatments' effects on juice quality, including bioactive compounds, color changes, and microbial inactivation, were examined. At similar doses, PL-treated samples (126 J/cm2) showed higher 2,2- diphenyl-1-picrylhydrazyl inhibition (9.5%) compared to UV-LED-treated samples (132 J/cm2), which showed 1.06%. For microbial inactivation, UV-LED achieved greater E. coli reduction (>3 log cycles) and less ascorbic acid degradation (9.4% ± 0.05) than PL. However, increasing PL doses to 176 J/cm2 resulted in more than 5 log cycles reduction of E. coli, showing a synergistic effect with the final temperature reached (55 °C). The Weibull model analyzed survival curves to evaluate inactivation kinetics. UV-LED was superior in preserving thermosensitive compounds, while PL excelled in deactivating more PPO and achieving maximal microbial inactivation more quickly.

Health effects of 100% fruit and vegetable juices: evidence from human subject intervention studies

The health effects of 100% fruit and vegetable juices (FVJ) represent a controversial topic. FVJ contain notable amounts of free sugars, but also vitamins, minerals, and secondary compounds with proven biological activities like (poly)phenols and carotenoids. The review aimed to shed light on the potential impact of 100% FVJ on human subject health, comprehensively assessing the role each type of juice may have in specific health outcomes for a particular target population, as reported in dietary interventions. The effects of a wide range of FVJ (orange, grapefruit, mandarin, lemon, apple, white, red, and Concord grapes, pomegranate, cranberry, chokeberry, blueberry, other minor berries, sweet and tart cherry, plum, tomato, carrot, beetroot, and watermelon, among others) were evaluated on a series of outcomes (anthropometric parameters, body composition, blood pressure and vascular function, lipid profile, glucose homeostasis, biomarkers of inflammation and oxidative stress, cognitive function, exercise performance, gut microbiota composition and bacterial infections), providing a thorough picture of the contribution of each FVJ to a health outcome. Some juices demonstrated their ability to exert potential preventive effects on some outcomes while others on other health outcomes, emphasising how the differential composition in bioactive compounds defines juice effects. Research gaps and future prospects were discussed. Although 100% FVJ appear to have beneficial effects on some cardiometabolic health outcomes, cognition and exercise performance, or neutral effects on anthropometric parameters and body composition, further efforts are needed to better understand the impact of 100% FVJ on human subject health.

A Novel Molecularly Imprinted Quartz Crystal Microbalance Sensor Based on Erbium Molybdate Incorporating Sulfur-Doped Graphitic Carbon Nitride for Dimethoate Determination in Apple Juice Samples

Dimethoate (DIM) as an organophosphorus pesticide is widely utilized especially in the cultivation of vegetables and fruits due to its killing effect on harmful insects. However, unconscious use of DIM in large amounts can also cause serious health problems. For these reasons, rapid and reliable detection of DIM from food samples is significant. In this study, a novel quartz crystal microbalance (QCM) sensor based on erbium molybdate incorporating sulfur-doped graphitic carbon nitride (EM/S-g-C3N4) and a molecularly imprinting polymer (MIP) was designed for DIM detection in apple juice samples. Firstly, an EM/S-g-C3N4 nanocomposite with high purity was prepared under hydrothermal conditions at high temperatures over a long period of time. After the modification of the EM/S-g-C3N4 nanocomposite on a QCM chip, the polymerization solution including N,N'-azobisisobutyronitrile (AIBN) as an initiator, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, methacryloylamidoglutamic acid (MAGA) as a monomer, and DIM as an analyte was prepared. Then, the polymerization solution was dropped on an EM/S-g-C3N4 nanocomposite modified QCM chip and an ultraviolet polymerization process was applied for the formation of the DIM-imprinted polymers on the EM/S-g-C3N4 nanocomposite modified QCM chip. After the polymerization treatment, some characterization studies, including electrochemical, microscopic, and spectroscopic methods, were performed to illuminate the surface properties of the nanocomposite and the prepared QCM sensor. The values of the limit of quantification (LOQ) and the detection limit (LOD) of the prepared QCM sensor were as 1.0 × 10-9 M and 3.3 × 10-10 M, respectively. In addition, high selectivity, stability, reproducibility, and repeatability of the developed sensor was observed, providing highly reliable analysis results. Finally, thanks to the prepared sensor, it may be possible to detect pesticides from different food and environmental samples in the future.

Nano‑selenium functionalized chitosan gel beads for Hg(II) removal from apple juice

The presence of potentially toxic elements and compounds poses threats to the quality and safety of fruit juices. Among these, Hg(II) is considered as one of the most poisonous heavy metals to human health. Traditional chitosan-based and selenide-based adsorbents face challenges such as poor adsorption capacity and inconvenient separation in juice applications. In this study, we prepared nano‑selenium functionalized chitosan gel beads (nanoSe@CBs) and illustrated the synergistic promotions between chitosan and nanoSe in removing Hg(II) from apple juice. The preparation conditions, adsorption behaviors, and adsorption mechanism of nanoSe@CBs were systematically investigated. The results revealed that the adsorption process was primarily controlled by chemical adsorption. At the 0.1 % dosage, the adsorbent exhibited high uptake, and the maximum adsorption capacity from the Langmuir isotherm model could reach 376.5 mg/g at room temperature. The adsorbent maintained high adsorption efficiency (> 90 %) across a wide range of Hg(II) concentrations (0.01 to 10 mg/L) and was unaffected by organic acids present in apple juice. Additionally, nanoSe@CBs showed negligible effects on the quality of apple juice. Overall, nanoSe@CBs open up possibilities to be used as a safe, low-cost and highly-efficient adsorbent for the removal of Hg(II) from juices and other liquid foods.

A genomics perspective of personalized prevention and management of obesity

This review discusses the landscape of personalized prevention and management of obesity from a nutrigenetics perspective. Focusing on macronutrient tailoring, we discuss the impact of genetic variation on responses to carbohydrate, lipid, protein, and fiber consumption. Our bioinformatic analysis of genomic variants guiding macronutrient intake revealed enrichment of pathways associated with circadian rhythm, melatonin metabolism, cholesterol and lipoprotein remodeling and PPAR signaling as potential targets of macronutrients for the management of obesity in relevant genetic backgrounds. Notably, our data-based in silico predictions suggest the potential of repurposing the SYK inhibitor fostamatinib for obesity treatment in relevant genetic profiles. In addition to dietary considerations, we address genetic variations guiding lifestyle changes in weight management, including exercise and chrononutrition. Finally, we emphasize the need for a refined understanding and expanded research into the complex genetic landscape underlying obesity and its management.

Unveiling Apple Diversity: The Quality of Juice Produced from Old vs. Commercial Apple Cultivars

This research is focused on comparing the compositions of juice produced from old and commercially grown apple cultivars. We examined factors such as pH, total acids, soluble dry matter, polyphenol profile, and antioxidant activity, which impact the attributes, safety, shelf life, and nutritional value of the juice. Our analysis revealed differences between these two groups of cultivars. For instance, pH values ranged from 3.04 (in 'Bobovec') to 3.69 (in 'Fuji'). The proportions of acids varied from 0.07 g/100 mL (in 'Fuji') to 0.19 g/100 mL (in 'Wagener'). Soluble dry matter content ranged from 14.10% (in 'Fuji') to 18.50% (in 'Kraljevčica'). We also observed variations in sugar content and composition among cultivars; for example, sucrose levels varied from 16.11 g/L ('Fuji') to 39.36 g/L ('Golden Delicious). Glucose levels ranged from 4.95 g/L ('Jonagold') to 19.18 g/L ('Fuji'), while fructose levels spanned from 50.78 g/L ('Austrougarka') to 427.97 g/L ('Ilzer Rosenapfel'). Furthermore, old apple cultivars exhibited higher concentrations of phenols and flavonoids compared to commercial ones; we also noted significant variations in flavonol levels among different cultivars. The 'Wagener' and 'Božićnica' apple varieties had levels of myricetin measuring 0.53 and 0.52 µg/mL, respectively. On the other hand, 'Bobovec' stood out for its content of procyanidin B2 with a concentration of 422.61 µg/mL. When examining non-flavonoid compounds, it was found that old apple cultivars had higher concentrations of gallic acid, trans-ferulic acid, and chlorogenic acid. However, commercial cultivars showed dominance in caffeic and p-coumaric. Comparisons of antioxidant capacity using DPPH and ABTS assays clearly demonstrated the superiority of old apple cultivars. Overall, this study highlights the importance of utilizing apple cultivars for juice production. Their distinct compositions and higher antioxidant capacities contribute to potential health benefits. Preserving these cultivars for enhanced juice quality and nutritional value is encouraged. Further research could explore cultivation practices' impact on composition and health benefits.

Targeting Nrf2 and NF-κB Signaling Pathways in Inflammatory Pain: The Role of Polyphenols from Thinned Apples

Diet can modulate the different stages of inflammation due to the presence of bioactive compounds such as polyphenols. Apples are a great source of phenolic compounds that show anti-inflammatory and antioxidant properties, and these might be used as a dietary supplement and/or functional element in the treatment of chronic inflammatory illnesses. The aim of our study was to evaluate the anti-inflammatory and antioxidant actions of thinned apple polyphenol (TAP) extracts in a model of paw edema. The experimental model was induced in rats via subplantar injections of 1% λ-Carrageenan (CAR) in the right hind leg, and TAP extract was administered via oral gavage 30 min before and 1 h after the CAR injection at doses of 5 mg/kg and 10 mg/kg, respectively. The inflammatory response is usually quantified by the increase in the size of the paw (edema), which is maximal about 5 h after the injection of CAR. CAR-induced inflammation generates the release of pro-inflammatory mediators and reactive oxygen species (ROS). Furthermore, the inflammatory state induces the pain that involves the peripheral nociceptors, but above all it acts centrally at the level of the spinal cord. Our results showed that the TAP extracts reduced paw histological changes, neutrophil infiltration, mast cell degranulation, and oxidative stress. Additionally, the oral administration of TAP extracts decreased thermal and mechanical hyperalgesia, along with a reduction in spinal microglia and the markers of nociception. In conclusion, we demonstrate that TAP extract is able to modulate inflammatory, oxidative, and painful processes, and is also useful in the treatment of the symptoms associated with paw edema.

Protective Effect of Apple Polyphenols on H₂O₂-Induced Oxidative Stress Damage in Human Colon Adenocarcinoma Caco-2 Cells

Apple is an important dietary agent for human and apple polyphenols (AP) are the main secondary metabolites of apples. In this study, the protective effects of AP on hydrogen peroxide (H₂O₂)-induced oxidative stress damage in human colon adenocarcinoma Caco-2 cells were investigated by cell viability, oxidative stress change as well as cell apoptosis. Pre-adding AP could significantly increase the survival rate of H₂O₂-treated Caco-2 cells. Besides, the activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) were elevated. While the malondialdehyde (MDA) content which is the major oxidant products of polyunsaturated fatty acids (PUFA) reduced after AP treatment. In addition, AP also suppressed the emergence of DNA fragment and decreased the expression of apoptosis-related protein Caspase-3. These results demonstrated that AP could ameliorate H₂O₂-induced oxidative stress damage in Caco-2 cells, which could serve as a reference for further studies of apple natural active products and deep study of the anti-oxidative stress mechanism.

Triterpenoids of Three Apple Cultivars—Biosynthesis, Antioxidative and Anti-Inflammatory Properties, and Fate during Processing

Triterpenoids are a group of secondary plant metabolites, with a remarkable pharmacological potential, occurring in the cuticular waxes of the aerial parts of plants. The aim of this study was to analyze triterpenoid variability in the fruits and leaves of three apple cultivars during the growing season and gain new insights into their health-promoting properties and fate during juice and purée production. The identification and quantification of the compounds of interest were conducted using gas chromatography coupled with mass spectrometry. The waxes of both matrices contained similar analytes; however, their quantitative patterns varied: triterpenic acids prevailed in the fruits, while higher contents of steroids and esterified forms were observed in the leaves. The total triterpenoid content per unit area was stable during the growing season; the percentage of esters increased in the later phases of growth. Antioxidative and anti-inflammatory properties were evaluated with a series of in vitro assays. Triterpenoids were found to be the main anti-inflammatory compounds in the apples, while their impact on antioxidant capacity was minor. The apples were processed on a lab scale to obtain juices and purées. The apple purée and cloudy juice contained only some of the triterpenoids present in the raw fruit, while the clear juices were virtually free of those lipophilic compounds.

Organic Juice Processing Quality from the Processors' Perspective: A Qualitative Study

Organic food quality is based on processing. While the EU organic production regulation focuses on agricultural production, private standards provide more detailed information about further processing. For the development of organic processing, practitioner perspectives can provide valuable input. To get insight into practitioner perspectives, we conducted semi-structured expert interviews with nine employees of seven partly organic juice processing companies from Germany and Austria. Interview topics were (i) quality of organic juice processing in general, (ii) assessment of specific processing techniques, (iii) product quality of organic juice and (iv) flow of information between producer and consumer. We conducted a thematic analysis. We found that the experts' understanding of process quality mostly includes more aspects than the EU organic production regulation. It covers the whole food chain plus aspects of social and environmental sustainability. The experts prefer directly bottled juice of local raw materials but chiefly accept juice made from concentrate of exotic raw materials because of environmental concerns. Organic juice is preferred when it is cloudy and natural fluctuations are interpreted as an indicator of natural quality. The experts report that consumer information is challenging because of low food literacy. Raising this might help reduce the number of processed juices on the market.

Antioxidant-Enriched Diet on Oxidative Stress and Inflammation Gene Expression: A Randomized Controlled Trial

The Mediterranean Diet (MedDiet) is associated with beneficial effects against chronic non-communicable diseases (CNCDs). In particular, the content of micronutrients leads to an improvement of the oxidative and inflammatory profiles. A randomized, parallel, controlled study, on 24 subjects, was conducted to evaluate if 2-week supplementation with a mixed apple and bergamot juice (MAB juice), had a positive impact on the body composition, the biochemical profile, and oxidative and inflammatory gene expression (Superoxide dismutase (SOD1), Peroxisome Proliferator-Activated Receptor γ (PPARγ), catalase (CAT), chemokine C-C motif ligand 5 (CCL5), Nuclear Factor Kappa B Subunit 1 (NFKB1), Vitamin D Receptor (VDR), and Macrophage Migration Inhibitory Factor (MIF)), respect to a MedDiet. Body composition evaluation analysis showed a gain in lean mass (p < 0.01). Moreover, a significant reduction in total cholesterol/HDL index (p < 0.01) was pointed out between the two groups. Gene expression analysis highlighted an increase in MIF (p ≤ 0.05), PPARγ (p < 0.001), SOD1 (p ≤ 0.05), and VDR (p ≤ 0.05) expressions when comparing MedDiet and MedDiet + MAB juice groups. These data based on the nutrigenomics approach demonstrated that supplementing 2 weeks of MAB juice to the MedDiet could contribute to a reduction in the risk of CNCDs.

Application of γ-aminobutyric acid (GABA) improves fruit quality and rootstock drought tolerance in apple

GABA (γ-aminobutyric acid) plays a multifaceted role in plant growth, fruit quality, and tolerance to abiotic stresses. However, its physiological roles and mechanisms in the fruit quality and response to long-term drought stress in apple remain unelucidated. To investigate the effect of GABA on apple fruit quality and drought tolerance, we sprayed exogenous GABA on apple cultivar "Cripps Pink" and irrigated rootstock M.9-T337 with GABA, respectively. Results showed that exogenous GABA could effectively improve the fruit quality of "Cripps Pink", including increased sugar-to-acid ratio, flesh firmness, pericarp malleability, and GABA content, as well as reduced fruit acidity. In addition, pretreatment of M.9-T337 plants with GABA improved their tolerance to both long- and short-term drought stress. Specifically, 1 mM exogenous GABA increased the net photosynthetic rate, relative leaf water content, root-to-shoot ratio, and water use efficiency under long-term drought stress, and delayed the increased of the relative electrolyte leakage under short-term drought stress. RNA-seq analysis identified 1271 differentially expressed genes (DEGs) between nontreated and GABA-pretreated plants under short-term drought stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of these DEGs revealed that GABA may enhance plant drought resistance by upregulating the expression of genes related to "Biosynthesis of secondary metabolites", "MAPK signaling pathway", "Glutathione metabolism", and "Carbon fixation in photosynthetic organisms". In conclusion, these results revealed that exogenous GABA can improve fruit quality and enhance drought tolerance in apple.

Distribution and Stability of Polyphenols in Juices Made from Traditional Apple Cultivars Grown in Bosnia and Herzegovina

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.

Bioactive potential of tropical highland apple (Malus domestica cv. Anna) crude extract: opportunities for food waste revalorization

Background

The third most produced fruit crop in the world, apples (Malus domestica Borkh) are one of the most accessible and widely consumed fruits, with known benefits for human health. Although they are a temperate crop, apple cultivation has been successfully implemented in lower latitudes. Tropical highland Costa Rican apples (cv. Anna) have shown high total polyphenol content, and cytotoxic effects against human cancer cell lines. However, most reports originate from purified fractions, obtained using methods which are not easily translatable for commercial applications. In this study, we prepared a polyphenol-rich bioactive extract from Costa Rican Anna apples, using food-grade solvents and simple techniques, aiming towards easy translation of the extraction protocols to small local producers.

Results

The whole apple crude extract (AE) was investigated for its total polyphenol content, general phytochemical profile, cytotoxicity against human breast and lung cancer cells, and regenerative potential in murine skin fibroblast monolayers. The AE showed total polyphenol amounts comparable to that obtained using more refined extractions in previous studies, and exhibited cytotoxic activity against human breast (MCF7) and lung (NCI-H460) cancer cells, and inhibition of cell proliferation in the scratch-wound-healing assay.

Conclusions

Food-grade simple protocols were successful for obtaining a polyphenol-rich bioactive extract from Costa Rican Anna apples. The easy-to-implement extraction protocols and biochemical tests could provide a source of bioactive phytochemicals to be used in circular production systems.

Polyphenols from Thinned Young Apples: HPLC-HRMS Profile and Evaluation of Their Anti-Oxidant and Anti-Inflammatory Activities by Proteomic Studies

The qualitative profile of thinned apple polyphenols (TAP) fraction (≈24% of polyphenols) obtained by purification through absorbent resin was fully investigated by LC-HRMS in positive and negative ion mode and using ESI source. A total of 68 polyphenols were identified belonging to six different classes: flavanols, flavonols, dihydrochalchones, flavanones, flavones and organic and phenolic acids. The antioxidant and anti-inflammatory activities were then investigated in cell models with gene reporter for NRF2 and NF-κB and by quantitative proteomic (label-free and SILAC) approaches. TAP dose-dependently activated NRF2 and in the same concentration range (10–250 µg/mL) inhibited NF-κB nuclear translocation induced by TNF-α and IL-1α as pro-inflammatory promoters. Proteomic studies elucidated the molecular pathways evoked by TAP treatment: activation of the NRF2 signaling pathway, which in turn up-regulates protective oxidoreductases and their nucleophilic substrates such as GSH and NADPH, the latter resulting from the up-regulation of the pentose phosphate pathway. The increase in the enzymatic antioxidant cellular activity together with the up-regulation of the heme-oxygenase would explain the anti-inflammatory effect of TAP. The results suggest that thinned apples can be considered as a valuable source of apple polyphenols to be used in health care products to prevent/treat oxidative and inflammatory chronic conditions.

Partial Removal of Sugar from Apple Juice by Nanofiltration and Discontinuous Diafiltration

Partial removal of sugars in fruit juices without compromising their biofunctional properties represents a significant technological challenge. The current study was aimed at evaluating the separation of sugars from phenolic compounds in apple juice by using three different spiral-wound nanofiltration (NF) membranes with a molecular weight cut-off (MWCO) in the range of 200–500 Da. A combination of diafiltration and batch concentration processes was investigated to produce apple juice with reduced sugar content and improved health properties thanks to the preservation and concentration of phenolic compounds. For all selected membranes, permeate flux and recovery rate of glucose, fructose, and phenolic compounds, in both diafiltration and concentration processes, were evaluated. The concentration factor of target compounds as a function of the volume reduction factor (VRF) as well as the amount of adsorbed compound on the membrane surface from mass balance analysis were also evaluated. Among the investigated membranes a thin-film composite membrane with an MWCO of 200–300 Da provided the best results in terms of the preservation of phenolic compounds in the selected operating conditions. More than 70% of phenolic compounds were recovered in the retentate stream while the content of sugars was reduced by about 60%.