Influence of variety and storage on the polyphenol composition of apple flesh

Effects of Polyphenol-Rich Foods on Lipids and Oxidative Stress Status in Patients with Hyperlipidemia: A Systematic Review of Randomized Controlled Trials

Background

Hyperlipidemia has been demonstrated to be an autonomous predictor of numerous cardiovascular and cerebrovascular ailments, and research indicates that polyphenols have preventive and therapeutic effects on hyperlipidemia. Nevertheless, the impact of polyphenol-rich foods on blood lipids and oxidative stress status in patients with hyperlipidemia remains inconclusive.

Objective

To examine the impact of polyphenol-rich foods on lipid levels and oxidative stress in individuals with hyperlipidemia.

Methods

To retrieve papers published from the establishment of the database through October 9, 2023, eight databases were searched: the Chinese National Knowledge Infrastructure, the China Biomedical Literature Database, the Wanfang Database, the China Science and Technology Journal Database, PubMed, the Cochrane Library, Embase, and the Web of Science. The quality of include studies was assessed using the Cochrane Risk of Bias in Randomized Trials tool, v2.

Results

The study involved 13 surveys encompassing 640 patients diagnosed with hyperlipidemia. The scope of the food surveys included 12 commonly consumed food groups and medicinal and food homologous substances. All 13 studies reported the effects of polyphenol-rich foods on blood lipids, with significant improvements observed in blood lipid levels for 9 types of foods. Eight studies examined the impact on oxidative stress, and six foods demonstrated a significant reduction in oxidative stress levels. The observed effects were found to be influenced by factors such as dosage, duration of intervention, and gender.

Conclusion

Foods abundant in polyphenols play a crucial role in the prevention and treatment of hyperlipidemia by counteracting oxidative stress and regulating metabolic disorders. The confirmation of certain positive effects by several studies notwithstanding, discrepancies in results arise from various factors, necessitating further large-scale, prospective, well-designed randomized controlled studies to address this issue.

Effects of Annurca Flesh Apple Polyphenols in Human Thyroid Cancer Cell Lines

Among natural macromolecules, the polyphenol extract from Annurca flesh (AFPE) apple could play a potential therapeutic role for a large spectrum of human cancer also by exerting antioxidant properties. Thyroid cancer is a common neoplasia in women, and it is in general responsive to treatments although patients may relapse and metastasize or therapy-related side effects could occur. In this study, we explored the effects of AFPE on papillary (TPC-1) and anaplastic (CAL62) thyroid cancer cell line proliferation and viability. We found that AFPE exposure induced a reduction of cell proliferation and cell viability in dose-dependent manner. The effect was associated with the reduction of phosphorylation of Rb protein. To study the mechanisms underlying the biological effects of AFPE treatment in thyroid cancer cells, we investigated the modulation of miRNA (miR) expression. We found that AFPE treatment increased the expression of the miR-141, miR-145, miR-200a-5p, miR-425, and miR-551b-5p. Additionally, since natural polyphenols could exert their beneficial effects through the antioxidant properties, we investigated this aspect, and we found that AFPE treatment reduced the production of reactive oxygen species (ROS) in CAL62 cells. Moreover, AFPE pretreatment protects against hydrogen peroxide-induced oxidative stress in thyroid cancer cell lines. Taken together, our findings suggest that AFPE, by acting at micromolar concentration in thyroid cancer cell lines, may be considered a promising adjuvant natural agent for thyroid cancer treatment approach.

Assessment of In Vitro Bioaccessibility of Polyphenols from Annurca, Limoncella, Red Delicious, and Golden Delicious Apples Using a Sequential Enzymatic Digestion Model

Four different varieties of apples have been considered (Limoncella, Annurca, Red Delicious, and Golden Delicious) to estimate the extent of colon polyphenolics release after in vitro sequential enzyme digestion. Since several studies report a positive effect of apple polyphenols in colonic damage, we found of interest to investigate the colon release of polyphenols in different varieties of apples in order to assess their prevention of colonic damage. UHPLC-HRMS analysis and antioxidant activity (ABTS, DPPH, and FRAP assays) were carried out on the apple extracts (peel, flesh, and whole fruit) obtained from not digested samples and on bioaccessible fractions (duodenal and colon bioaccessible fractions) after in vitro digestion. Polyphenolic content and antioxidant activities were found to vary significantly among the tested cultivars with Limoncella showing the highest polyphenol content accompanied by an excellent antioxidant activity in both flesh and whole fruit. The overall trend of soluble antioxidant capacity from the soluble duodenal phase (SDP) and soluble colonic phase (SCP) followed the concentrations of flavanols, procyandinis, and hydroxycinnamic acids under the same digestive steps. Our results highlighted that on average 64.2% of the total soluble antioxidant activity was released in the SCP with Limoncella exhibiting the highest values (82.31, 70.05, and 65.5%, respectively for whole fruit, flesh, and peel). This result suggested that enzymatic treatment with pronase E and viscozyme L, to reproduce biochemical conditions occurring in the colon, is effective for breaking the dietary fiber-polyphenols interactions and for the release of polyphenols which can exercise their beneficial effects in the colon. The beneficial effects related to the Limoncella consumption could thus be of potential great relevance to counteract the adverse effects of pro-oxidant and inflammatory processes on intestinal cells.

The Perspective of Croatian Old Apple Cultivars in Extensive Farming for the Production of Functional Foods

The Republic of Croatia has a long tradition of fruit growing due to its geographical location, climatic conditions, and high quality of fruit crops, especially apple fruits. Apples can be used for the formulation of functional foods either in processed form (e.g., juice), or as a by-product (e.g., apple pomace). However, there is a growing demand for functional foods derived from ancient and traditional plant sources as they are recognized as a very valuable source of health-promoting bioactive ingredients. Similarly, old apple cultivars (Malus domestica Borkh.) are characterized by good morphological and pomological properties, less need for chemicals during cultivation and the higher share of biologically active compounds (BACs) with better sensory acceptability compared to commercial cultivars. However, their nutritional and biological potential is underestimated, as is their ability to be processed into functional food. The importance in preserving old apple cultivars can also be seen in their significance for improving the nutritional composition of other apple cultivars through innovative cultivation strategies, and therefore old local apple cultivars could be of great importance in future breeding programs.

The Differences in the Flavan-3-ol and Procyanidin Contents of the Japanese 'Fuji' and 'Orin' Apples Using a Rapid Quantitative High-Performance Liquid Chromatography Method: Estimation of the Japanese Intake of Flavan-3-ols and Procyanidins from Apple as Case Study

Previously, we reported that apple polyphenols and their major active compounds, the flavan-3-ols and the procyanidins, can result in various health benefits in animals and humans, according to clinical studies. Here, we developed a rapid method for quantifying flavan-3-ols and procyanidins using high-performance liquid chromatography with fluorescence detection, where we investigated the amounts of flavan-3-ols and procyanidins in the Japanese major apple production centre, the Aomori Prefecture, from 2016 to 2018. The non-bagged ‘Fuji (n = 609)’, the bagged ‘Fuji (n = 1101)’, and the ‘Orin (n = 504)’ apples were evaluated in terms of their differences in flavan-3-ols and procyanidins based on apple variety and the controlled atmosphere storage. The bagging treatments of the ‘Fuji’ apples resulted in significantly higher concentrations of procyanidins, while changes in flavan-3-ols concentrations were not clearly observed by treatment. In addition, ‘Orin’ had a significantly higher concentration of procyanidins than that of ‘Fuji’. In contrast, the controlled atmosphere storage hardly caused any changes in the flavan-3-ol and procyanidin contents. Hence, we present the concentrations of flavan-3-ols and procyanidins in major Japanese apples using the rapid high-performance liquid chromatography method with fluorescence detection.

Annurca Apple Polyphenol Extract Affects Acetyl- Cholinesterase and Mono-Amine Oxidase In Vitro Enzyme Activity

In this study, we explored the ability of Annurca apple flesh polyphenol extract (AFPE) to affect the activity of key enzymes involved in neurodegenerative disorders—in particular, Acetyl- and Butirryl-cholinesterases, and type A and B monoamine oxidase. The effect of AFPE on enzyme activity was analyzed by in vitro enzyme assays, and the results showed concentration-dependent enzyme inhibition, with IC₅₀ values corresponding to 859 ± 18 µM and 966 ± 72 µM for AChE and BuChE respectively, and IC₅₀ corresponding to 145 ± 3 µM and 199 ± 7 µM for MAO-A and MAO-B, respectively, with a preference for MAO-A. Moreover, in this concentration range, AFPE did not affect the viability of human neuroblastoma SH-SY5Y and fibroblast BJ-5ta cell lines, as determined by an MTT assay. In conclusion, our results demonstrate that AFPE shows the new biological properties of inhibiting the activity of enzymes that are involved in brain functions, neurodegenerative disorders, and aging.

Systematic Review of Phenolic Compounds in Apple Fruits: Compositions, Distribution, Absorption, Metabolism, and Processing Stability

As the most widely consumed fruit in the world, apple (Malus domestica Borkh.) fruits provide a high level of phenolics and have many beneficial effects on human health. The composition and content of phenolic compounds in natural apples differs according to the tissue types and cultivar varieties. The bioavailability of apple-derived phenolics, depending on the absorption and metabolism of phenolics during digestion, is the key determinant of their positive biological effects. Meanwhile, various processing technologies affect the composition and content of phenolic compounds in apple products, further affecting the bioavailability of apple phenolics. This review summarizes current understanding on the compositions, distribution, absorption, and metabolism of phenolic compounds in apple and their stability when subjected to common technologies during processing. We intend to provide an updated overview on apple phenolics and also suggest some perspectives for future research of apple phenolics.

Electroactive Phenolic Contributors and Antioxidant Capacity of Flesh and Peel of 11 Apple Cultivars Measured by Cyclic Voltammetry and HPLC-DAD-MS/MS

In this study, 11 apple cultivars were characterized by their total phenolic content (TPC) and total flavonoid content (TFC) and antioxidant, reducing, and chelating capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, cyclic voltammetry (CV), and ferric reducing antioxidant power (FRAP) assays; and ferrous ion chelating capacity. The phenolic compounds in flesh and peel were determined by liquid chromatography coupled to mass spectrometry and diode array detector (HPLC-DAD-MS/MS) and their electroactivity by CV. The results showed higher TPC, TFC, and antioxidant capacity by DPPH test in the peels of all apple cultivars as compared to the respective flesh. The peel extracts also showed two-fold higher FRAP values as compared to the flesh extracts. The reducing capacity of the peel and flesh determined by CV measurements confirmed the results achieved by spectrophotometric methods of evaluating antioxidant capacity. There was no significant difference in chelating capacity in the peel and flesh. The HPLC-DAD-MS/MS analysis showed the presence of 11 phenolic compounds in the peel and flesh which varied in antioxidant, reducing, and chelating activity. The order of the phenolic compound content in flesh and peel in Quinte cultivar, which showed the highest antioxidant capacity, was as follows: epicatechin > chlorogenic acid > quercetin 3-arabinoside > quercetin 3-glucoside > cyanidin 3-galactoside > quercetin 3-rhamnoside > catechin > phloridzin > rutin > phloretin = quercetin. CV results were highly correlated with those obtained by spectrophotometry and HPLC-DAD-MS/MS, providing evidence to support the use of cyclic voltammetry as a rapid method to determine the phenolic profile and reducing the power of apple flesh and peel. The association between antioxidant assays and phenolic compound content showed that the highest contribution to the antioxidant capacity of apple peel and flesh was provided by catechin, epicatechin, and cyadinin-3-galactoside, while phloretin, phloridzin, and chlorogenic acid were the main contributors to chelating activity. Results from this study clearly indicate that removing the peel from apples may induce a significant loss of antioxidants.

Biological Activity of MelAnnurca Flesh Apple Biophenols

Background:

The apple is among the most consumed fruits in the world and several studies suggest that apple polyphenols could play a role in preventing degenerative diseases. Recent studies have shown that polyphenols possess a high antioxidant and/or anti-proliferative power, therefore their food intake could play a decisive role in the prevention of various pathologies, in particular those associated with the production of free radicals. The Annurca apple (MelAnnurca), a variety from southern Italy, is called the "queen of apples" due to its remarkable organoleptic qualities: taste, flavor and aroma. The Annurca apple is a constituent component of the Mediterranean diet and its potential health benefit could be attributed to a large amount of bioactive components; in fact, this apple is characterized by an extremely high content of polyphenols.

Objective:

The aim of this paper was to review the most recent literature regarding the health benefits of Annurca apples and their phytochemicals. In particular, this review highlighted the effects of the flesh of this fruit on different types of human cells.

Methods:

A literature research was performed using the keywords “Annurca”, “apple”, “flesh”, “fruit”, “polyphenols”, “nutrition”, “nutraceuticals”, individually or all together, in Scopus, Web of Science and PubMed.

Results:

The MelAnnurca apple has a higher content of bioactive compounds (polyphenols) than other apples, making it an ideal source of nutraceuticals. Both the cytotoxic activity and the antioxidant effect of the extracts of polyphenols obtained from its flesh have been highlighted.

Conclusion:

These results give new insights for future implementation of the production chain of the Annurca apple in the area of Campania, Southern Italy. However, although evidence to support the health benefits of MelAnnurca apple polyphenols is rapidly accumulating, further human studies may be needed before the public is convinced and willing to incorporate the apple Annurca into their diet, accepting the idea that the integration of polyphenols has a beneficial effect on the health of the human body.

Antioxidant and hepatoprotective effects against acute CCl4 -induced liver damage in mice from red-fleshed apple flesh flavonoid extract

Apple (Malus domestica Borkh.) is an important fruit tree species worldwide. Apple fruits are favored by consumers because of their antioxidative, anti-inflammatory, and antitumor effects as well as their protective effects against cardiovascular diseases and other health benefits. There is considerable interest in red-fleshed apple fruits among breeders because of their high flavonoid and anthocyanin contents. However, the flavonoids extracted from red-fleshed apple fruits must still be functionally characterized, especially regarding their protective effects against certain pathologies. In this study, the flavonoid components and contents in the extracts prepared from red-fleshed apple cultivar "Meihong" were determined. Additionally, the in vitro antioxidant activities and protective effects of the extracts against CCl₄ -induced acute liver injury were investigated. The red-fleshed apple flesh flavonoid extract (RAFF) exhibited strong in vitro antioxidant activities. Compared with the model control mice treated with CCl₄ , the mice pretreated with high (800 mg/kg·bw), middle (400 mg/kg·bw), and low (200 mg/kg·bw) RAFF doses had significantly lower CCl₄ -induced serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities. Moreover, the RAFF pretreatment also significantly decreased the liver malondialdehyde activity and prevented the CCl₄ -induced decrease in liver superoxide dismutase, glutathione peroxidase, catalase, and reduced glutathione levels. Furthermore, a histopathological examination revealed that RAFF inhibited the inflammatory cell infiltration and cell boundary loss caused by CCl₄ in the liver. Thus, RAFF is a natural antioxidant with significant antioxidative activities and liver protective effects. The results of this study may be relevant for enhancing the application of the red-fleshed apple fruit extract as a food additive. PRACTICAL APPLICATION: We took the self-selected red-fleshed apple cultivar "Meihong" as the unique research material, and the active ingredients of its flavonoid extract, in vitro antioxidant activity and hepatoprotective effect were analyzed. It is of great significance to promote the development of the red-fleshed apple industry, and also provides an important reference for the development of natural antioxidants.

Effects of Biostimulants on Annurca Fruit Quality and Potential Nutraceutical Compounds at Harvest and during Storage

The cultivar Annurca is an apple that is cultivated in southern Italy that undergoes a typical redding treatment and it is appreciated for organoleptic characteristics, high pulp firmness, and nutritional profile. In this study, the effects of three different biostimulants (Micro-algae (MA), Protein hydrolysate (PEP), and Macro-algae mixed with zinc and potassium (LG)), with foliar application, on the quality parameters of Annurca apple fruits at the harvest, after redding, and at +60 and +120 days of cold storage were analyzed: total soluble solids (TSS) content, total acidity (TA), pH, firmness flesh, and red coloration of epicarp. Additionally, the polyphenolic quali-quantitative profile of pulp and peel was analyzed by UHPLC-Q-Orbitrap HRMS and Folin-Ciocalteu and the antioxidant capacity with the methods 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric-reducing antioxidant capacity (FRAP). The results obtained suggest that biostimulants are involved in the regulation of the secondary metabolism of the treated plants, acting positively on the quality of the Annurca fruits and their nutritional value. Fruits treated with PEP have shown, during cold storage, a significantly higher content of total polyphenols in flesh and a higher concentration of phloretin xylo-glucoside and phloridzin (350.53 and 43.58 mg/kg dw respectively). MA treatment caused, at the same time, an enhancement of flavonols between 0.6–28% and showed the highest total polyphenol content in the peel after 60 and 120 days of cold storage, with 2696.048 and 2570.457 mg/kg dw, respectively. The long-term cold storage (120 days) satisfactorily maintained phenolic content of fruits deriving from MA and PEP application, in accordance with data that were obtained for peel, showed an increase of 7.8 and 5.8%, respectively, when compared to the fruits cold stored for 60 days. This study represents the first detailed research on the use of different types of biostimulants on the quality of the Annurca apple from harvest to storage.

Metabolite Profiling and Antioxidant Activity of 10 New Early- to Mid-Season Apple Cultivars and 14 Traditional Cultivars

Early- to mid-season apple cultivars have recently been developed in response to global warming; however, their metabolite compositions remain unclear. Herein, metabolites, such as free sugars, and organic acids and antioxidant activity were determined in 10 new and 14 traditional apple cultivars. Additionally, the phenolic profiles of the apple pulp and peel were characterized by high-resolution mass spectrometry. Major phenolic compounds in apples varied depending on the cultivar and tissue (i.e., peel or pulp). Among the new apple cultivars, Decobell and Tinkerbell, showed high antioxidant activity and contained higher phenolic compound content than other cultivars in the peel and pulp, respectively. Honggeum showed high phenolic content with similar sugar to acid ratio compared to popular traditional cultivars. In addition to antioxidant phenolic contents, metabolite profile information can be used to select apple cultivars for various purposes. For example, Indo can be selected for sweet apple taste because of its higher sugar to acid ratio. This information can be used to select apple cultivars for various purposes. For example, Decobell peel could be used as sources of food supplements and food additives, and Tinkerbell pulp can be utilized for apple juice making according to its metabolite profile.

Postharvest changes in phenolic compounds and antioxidant capacity of apples cv. Jonagold growing in different locations in Europe

Apples cv. 'Jonagold' of the same quality were collected from four orchards in three European countries. The orchards differed in terms of longitude, latitude and microclimate. The apples were stored in controlled atmosphere storage for six months. Both after harvest and after storage the apples were compared in terms of physical and chemical properties. Differences in firmness, titratable acidity, total soluble solids, mass varied not >11%. Storability was little affected by harvest location. The sum of polyphenols was more strongly influenced by storage than by orchard location. The strongest degradation of flavonols after storage was in apples grown in the most southern region of harvest (Italy). The content of (+)- catechin and (-)-epicatechin depended on harvest location and its strong increase resulted in higher content of procyanidins and flavanols after storage. Changes in individual polyphenols were significant after storage and depended on harvest location.

Effects of Annurca Apple (Malus pumila cv Annurca) Polyphenols on Breast Cancer Cells

Background:

Dietary micronutrients have been proposed as effective inhibitory agents for cancer initiation, progression, and incidence. Among them, polyphenols, present in different foods and beverages, have retained attention in recent years. Apples are among the most consumed fruits worldwide, and several studies suggest that apple polyphenols could play a role in the prevention of degenerative diseases.

Aims and Objectives:

The present study aimed at evaluating the effects of Annurca flesh polyphenols extract (AFPE) effects of proliferation on MCF-7 cells.

Methods:

The data indicated that apple polyphenolic compounds had a significant antiproliferative action on MCF-7 cells and 500μM EqC AFPE induced a cell cycle arrest at G2/M. AFPE was also capable of inducing morphological changes as evidenced by nuclear condensation.

Results:

The cellular, morphological, and molecular data unequivocally suggested that induction of cellular apoptosis was mainly responsible for the previously observed antiproliferation-induced AFPE on MCF-7 cells.

Conclusion:

Taken together, AFPE that acts at a low micromolar range against breast cancer cells may be considered as a promising candidate for anticancer therapy.

Response of organic and conventional apples to freezing and freezing pre-treatments: Focus on polyphenols content and antioxidant activity

The effect of pre-treatment (dipping and vacuum impregnation in lemon juice solution), freezing and frozen storage (FS) on single and total polyphenols (free and conjugated) content and antioxidant activity (AOA) of organic and conventional apples, was investigated. Fresh organic and conventional fruits showed different profiles of free and conjugated polyphenols while their total phenolic content and AOA were similar. Organic and conventional apple tissues showed different physiological responses to physical stresses described by changes in phenolic profiles. Vacuum impregnation in lemon juice affected the polyphenols extractability of both the organic and conventional apples and favored their enrichment with bioactive compounds (AOA = +11.5%). FS decreased the single and conjugated polyphenols content of the pre-treated apple samples and the effect was different between organic and conventional fruits. After FS, not pre-treated organic apples showed a lower AOA reduction than the conventional ones (-13% vs -25%), while no differences were found on pre-treated samples.

Annurca apple polyphenol extract selectively kills MDA-MB-231 cells through ROS generation, sustained JNK activation and cell growth and survival inhibition

Polyphenols represent the most studied class of nutraceuticals that can be therapeutics for a large spectrum of diseases, including cancer. In this study, we investigated for the first time the antitumor activities of polyphenol extract from Annurca apple (APE) in MDA-MB-231 triple negative breast cancer cells, and we explored the underlying mechanisms. APE selectively inhibited MDA-MB-231 cell viability and caused G2/M phase arrest associated with p27 and phospho-cdc25C upregulation and with p21 downregulation. APE promoted reactive oxygen species (ROS) generation in MDA-MB-231 cells while it acted as antioxidant in non-tumorigenic MCF10A cells. We demonstrated that ROS generation represented the primary step of APE antitumor activity as pretreatment with antioxidant N-acetylcysteine (NAC) prevented APE-induced G2/M phase arrest, apoptosis, and autophagy. APE downregulated Dusp-1 and induced a significant increase in JNK/c-Jun phosphorylation that were both prevented by NAC. Moreover, downregulation of JNK by its specific inhibitor SP600125 significantly diminished the anticancer activity of APE indicating that ROS generation and sustained JNK activation represented the main underlying mechanism of APE-induced cell death. APE also inhibited AKT activation and downregulated several oncoproteins, such as NF-kB, c-myc, and β-catenin. In light of these results, APE may be an attractive candidate for drug development against triple negative breast cancer.

Screening of ordinary commercial varieties of apple fruits under different storage conditions for their potential vascular and metabolic protective properties

Epidemiological studies reported that apple consumption is associated with a decrease of cardiovascular and metabolic dysfunction, probably due to the polyphenols and fibers present in this fruit. The storage conditions and genetic origin of apples have been reported to influence their content and, as a consequence, their pharmacological properties. The present study evaluated the influence of varieties and storage conditions of traditional and highly appreciated apples including Gala, Golden Delicious, Granny Smith and Pink Lady varieties after harvest and storage under classic cold conditions, under a controlled atmosphere, or under extreme ultra-low oxygen conditions. Thus, a multi-parametric screening on cell models associated with vascular and metabolic dysfunctions - such as endothelial and smooth muscle cells, hepatocytes, adipocytes and macrophages - in relation to the apple polyphenol content has been developed. This strategy demonstrated that, overall, peeled apple samples exhibited a vascular tropism and acted mainly on proliferation and oxidative stress in endothelial and smooth muscle cells. Apple extracts appeared to be less effective on adipocytes and macrophages, but they exhibited antioxidant properties in hepatocytes. Among the varieties, Gala and Golden Delicious were the most efficient against the processes involved in the development of atherosclerosis. Concerning storage conditions, most of the apple varieties were more efficient under harvest conditions, while they could not be discriminated under all other cold conditions and the concentration used, except for the Gala samples. Interestingly, pharmacological properties were associated with the polyphenol profiles of freeze dried apple flesh powder. The present report revealed the potential use of some apple extracts as effective food supplements or nutraceuticals for the prevention and/or management of cardiovascular and metabolic diseases.

Enzymatic browning reaction of apple juices prepared using a blender and a low-speed masticating household juicer

The aim of this study was to investigate the effect of juicer type (blender or LSM household juicer) on the browning reaction of apple juice and evaluate the remaining antioxidant activity in the juice. The blender apple juice showed a darker brown color and 4.5 times higher PPO activity than LSM apple juice. This result suggested that the blender caused severer damage to plastids in cells leading to leakage of PPO into the juice than the LSM juicer. The total polyphenol and flavonoid content of LSM apple juice was approximately 2 times higher than that of blender apple juice because polyphenols and flavonoids can be used as substrates by PPO. The antioxidant activity of LSM juice was higher than that of blender juice. Together, these results suggested that the LSM juicer is superior to the blender for preparation of fresh apple juices due to the minimization of enzymatic oxidation reactions. Abbreviations: LSM: low-speed masticating; PPO: polyphenol oxidase; ABTS: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); DPPH: 2,2-diphenyl-1-picrylhydrazyl.

Polyphenolic Compounds Analysis of Old and New Apple Cultivars and Contribution of Polyphenolic Profile to the In Vitro Antioxidant Capacity

Polyphenols are antioxidant ingredients in apples and are related to human health because of their free radical scavenging activities. The polyphenolic profiles of old and new apple cultivars (n = 15) were analysed using high-performance liquid chromatography (HPLC) with diode array detection (DAD). The in vitro antioxidant capacity was determined by total phenolic content (TPC) assay, hydrophilic trolox equivalent antioxidant capacity (H-TEAC) assay and hydrophilic oxygen radical absorbance (H-ORAC) assay. Twenty polyphenolic compounds were identified in all investigated apples by HPLC analysis. Quercetin glycosides (203 ± 108 mg/100 g) were the main polyphenols in the peel and phenolic acids (10 ± 5 mg/100 g) in the flesh. The calculated relative contribution of single compounds indicated flavonols (peel) and vitamin C (flesh) as the major contributors to the antioxidant capacity, in all cultivars investigated. The polyphenolic content (HPLC data) of the flesh differed significantly between old (29 ± 7 mg/100 g) and new (13 ± 4 mg/100 g) cultivars, and the antioxidant capacity of old apple cultivars was up to 30% stronger compared to new ones.

Influence of 1-Methylcyclopropene Treatment on Postharvest Quality of Four Scab (Venturia inaequalis)-Resistant Apple Cultivars

Scab (Venturia inaequalis) is a very serious disease for apples causing up to 80% of loss in yield but there are only a few studies on postharvest quality of scab-resistant cultivars. In this study we evaluated the effect of 1-methylcyclopropene (1-MCP) on fruit quality, total phenolic content, and antioxidant capacity after storage of four scab-resistant cultivars and compared to a standard cultivar, “Golden Delicious.” In general, ethylene production and respiration rates significantly differed among cultivars, between control and 1-MCP-treated fruits, and between storage duration regimes. 1-MCP treatment retarded fruit softening and lowered juice pH but storage effect on soluble solids and acidity depended on cultivar and 1-MCP treatment. Total phenolic content was significantly affected by storage duration and 1-MCP treatment. Antioxidant capacity of the four scab-resistant cultivars was either similar to or significantly higher than that of “Golden Delicious” with the 1-MCP-treated fruits having significantly higher antioxidant capacity than the nontreated fruits after storage. Our results clearly show that the quality of four scab-resistant cultivars was comparable to that of “Golden Delicious” and 1-MCP effect differed among cultivars. These differences need to be considered in developing storage regime to minimize quality deterioration during long-term storage.

Characterization of the Polyphenolic Profiles of Peel, Flesh and Leaves of Malus domestica Cultivars Using UHPLC-DAD-HESI-MSn

Qualitative and quantitative analyses of polyphenols extracted from 21 Malus domestica cultivars using ultra high performance liquid chromatography with diode array detection coupled to heated electrospray ionization mass spectrometric detection was performed for separation of 27 phenolic compounds on a reversed phase UHPLC column with an optimized gradient consisting of 1% formic acid in water and 1% formic acid in methanol within 20 minutes. According to retention times, UV maxima and mass spectra of the peaks in the chromatograms obtained from extracts of apple peel, flesh and leaves, the polyphenolic compounds were identified and quantified. Based on fragmentation patterns, 6 phenolic acids, 5 flavan-3-ols, 5 dihydrochalcones, 8 flavonols and 3 flavone derivatives were characterized in the studied samples. The method was then employed for analysis of the polyphenolic pattern of 21 apple cultivars, both commercial and autochthonous for the Macedonian region, as well as for monitoring the influence of long term storage on the polyphenolic content and composition of apple fruits and for comparison of polyphenolic profiles of apple cultivars during two years of harvesting. The obtained results revealed minor differences in the quality and major variation in the content of phenolic compounds in the flesh, peel and leaves in the studied apple cultivars that is attributed mainly to cultivar differences and meteorological factors.

Evaluation of different training systems on Annurca apple fruits revealed by agronomical, qualitative and NMR-based metabolomic approaches

Nine different training systems for "Annurca Rossa del Sud" apple fruits, including oblique palmette, free palmette, V-shaped, Tatura trellis, Bibaum®, modified Bibaum®, triple leader, slender spindle and Solaxe, were evaluated based on agronomic, qualitative and metabolomic traits. Fruits were analysed at harvest and after the reddening process. The slender spindle training system showed the highest cumulative efficiency yield compared to the others. Furthermore, an increase in the content of bioactive compounds in flesh and fruit peels was observed after the reddening process and was influenced by the different training systems. The metabolic variations in apple peel were measured and analysed. Changes in the metabolome highlight the influence of different training systems on apple quality. This multidisciplinary study expands our knowledge of the influence of training systems on a typical Italian apple cultivar.

1H NMR and PCA-based analysis revealed variety dependent changes in phenolic contents of apple fruit after drying

Dry and fresh apples have been studied monitoring their polyphenolic profiles through ¹H NMR, antioxidant capacity and total polyphenol content. Six ancient and underutilized apple varieties (Mantovana, Mora, Nesta, Cipolla, Ruggina, Sassola) and a commercial one (Golden Delicious) were dried with an air-drying system at 45°C for 19h. Although some of their polyphenol constituents were lost during drying, the antioxidant capacity of some apple varieties remained higher compared to Golden Delicious. This result is very important for ancient and underutilized varieties that are not consumed on large scale as fresh product since they have low attractiveness, due to their ugly appearance. Combining quantitative NMR spectroscopy with principal component analysis we have identified and quantified several polyphenols (such as catechin, epicathechin, and chlorogenic acid) that are important to establish the nutraceutical value of the different investigated apple varieties.

A theoretical study on predicted protein targets of apple polyphenols and possible mechanisms of chemoprevention in colorectal cancer

We investigated the potential role of apple phenolic compounds in human pathologies by integrating chemical characterization of phenolic compounds in three apple varieties, computational approaches to identify potential protein targets of the compounds, bioinformatics analyses on data from public archive of gene expression data, and functional analyses to hypothesize the effects of the selected compounds in molecular pathways. Starting by the analytic characterization of phenolic compounds in three apple varieties, i.e. Annurca, Red Delicious, and Golden Delicious, we used computational approaches to verify by reverse docking the potential protein targets of the identified compounds. Direct docking validation of the potential protein-ligand interactions has generated a short list of human proteins potentially bound by the apple phenolic compounds. By considering the known chemo-preventive role of apple antioxidants' extracts against some human pathologies, we performed a functional analysis by comparison with experimental gene expression data and interaction networks, obtained from public repositories. The results suggest the hypothesis that chemo-preventive effects of apple extracts in human pathologies, in particular for colorectal cancer, may be the interference with the activity of nucleotide metabolism and methylation enzymes, similarly to some classes of anticancer drugs.

Detailed polyphenolic profiling of Annurca apple (M. pumila Miller cv Annurca) by a combination of RP-UHPLC and HILIC, both hyphenated to IT-TOF mass spectrometry

Annurca apple, a Southern Italian cultivar, possesses not only a particular taste and flavor, different from other types of apple, but also several healthy properties. With the aim to thoroughly elucidate the polyphenolic profile of this variety, listed as Protected Geographical Indication product, an extensive qualitative profiling of Annurca apple polyphenolic peel extract was carried out, by employing a combination of ultra high performance reversed phase (RP-UHPLC) and hydrophilic liquid chromatography (HILIC) coupled to ion trap-time of flight (IT-TOF) mass spectrometry. A total of 63 compounds were tentatively identified, 25 of which not reported in Annurca apple extract so far. Furthermore, thanks to the different selectivity obtained with the HILIC, in combination with accurate mass measurements, an improved separation and detection of procyanidins, was obtained. Moreover, the obtained profiles were compared with those of a conventional variety, such as Red Delicious (RD), highlighting their differences. This work contributes to increase the knowledge about the polyphenolic fingerprint of this typical apple variety.

Differential protective effects of polyphenol extracts from apple peels and fleshes against acute CCl4-induced liver damage in mice

The present study reports the phenolic profiles and antioxidant and hepatoprotective properties of Red Fuji apple peel polyphenolic extract (APP) and its flesh polyphenolic extract (AFP) against CCl₄-induced acute hepatic damage in mice.

Organic food processing: a framework for concept, starting definitions and evaluation

In 2007 EU Regulation (EC) 834/2007 introduced principles and criteria for organic food processing. These regulations have been analysed and discussed in several scientific publications and research project reports. Recently, organic food quality was described by principles, aspects and criteria. These principles from organic agriculture were verified and adapted for organic food processing. Different levels for evaluation were suggested. In another document, underlying paradigms and consumer perception of organic food were reviewed against functional food, resulting in identifying integral product identity as the underlying paradigm and a holistic quality view connected to naturalness as consumers' perception of organic food quality. In a European study, the quality concept was applied to the organic food chain, resulting in a problem, namely that clear principles and related criteria were missing to evaluate processing methods. Therefore the goal of this paper is to describe and discuss the topic of organic food processing to make it operational. A conceptual background for organic food processing is given by verifying the underlying paradigms and principles of organic farming and organic food as well as on organic processing. The proposed definition connects organic processing to related systems such as minimal, sustainable and careful, gentle processing, and describes clear principles and related criteria. Based on food examples, such as milk with different heat treatments, the concept and definitions were verified. Organic processing can be defined by clear paradigms and principles and evaluated according criteria from a multidimensional approach. Further work has to be done on developing indicators and parameters for assessment of organic food quality.

Release of antioxidant capacity from five plant foods during a multistep enzymatic digestion protocol

This study aimed at elucidating the influence of food matrix on the release of antioxidant activity from five plant foods (apple, spinach, walnut, red bean, and whole wheat). To this purpose a protocol based on sequential enzymatic digestion was adopted. The total antioxidant capacity (TAC) of both solubilized and insoluble materials was measured at each step. Results showed that the overall TAC obtained by enzyme treatments was usually higher than that obtained by chemical extraction-based methods. In apple most of the TAC was released upon water washing and after pepsin treatment, whereas in spinach, beans, and whole wheat the TAC released by treatments with bacterial enzymes was prominent. Walnut had the highest TAC value, which was mainly released after pancreatin treatment. Therefore, the enzyme treatment is fundamental to estimate the overall potential TAC of foods having a high amount of polyphenols bound to dietary fiber or entrapped in the food matrix.

Effects of sugar addition on total polyphenol content and antioxidant activity of frozen and freeze-dried apple purée

The objective of this study was to investigate the influence of simple sugar addition including (glucose, G; fructose, F; sucrose, S; and trehalose, T) on the total polyphenol content (TPC) and antioxidant activity (AOA) of apple purée processed by freezing and freeze-drying and stored for 6 months. The apple polyphenol profile was mostly preserved in the freeze-dried samples with sugar addition during 6 months of storage, whereas the polyphenol profile in frozen samples consists only of quercetin glycosides, of which rutin had the largest share. After 6 months, the highest level of polyphenols was detected in frozen 'Idared' and 'Fuji' apple purée with addition of T 5% (12.2 and 16.7 mg/100 g FW, respectively), whereas in freeze-dried apple purée the highest TPC was in 'Idared' and 'Fuji' with addition of T 1% (16.3 and 13.6 mg/100 g FW, respectively). Results indicate that sugar addition before processing could have potential for enhancing product quality.

Phenolic Compounds in Apple (Malus x domestica Borkh.): Compounds Characterization and Stability during Postharvest and after Processing

This paper summarizes the information on the occurrence of phenolic compounds in apple (Malus x domestica Borkh.) fruit and juice, with special reference to their health related properties. As phytochemical molecules belonging to polyphenols are numerous, we will focus on the main apples phenolic compounds with special reference to changes induced by apple cultivar, breeding approaches, fruit postharvest and transformation into juice.

Correlation between changes in polyphenol composition of peels and incidence of CO₂ skin burning of 'Cameo' apples as influenced by controlled atmosphere storage

'Cameo' apples stored under high CO₂ levels suffer from "skin burning". Accordingly, this study is aimed to correlate the incidence of skin burning with different polyphenols. After harvest, apples were sorted into bad- and good-colored fruit and further stored under either high (3%) or low (0.7%) CO₂ level. At frequent intervals, fruit were assessed for incidence of skin burning and relative concentrations of various polyphenols. Results clearly show that bad-colored apples stored under high CO₂ level had the highest incidence percentage. Concerning the polyphenol profile, good-colored and healthy apples had significantly higher concentrations of certain polyphenols, including cyanidin-3-galactoside and rutin. However, bad-colored and injured apples had significantly higher concentrations of another set of polyphenols, including phloridzin, epicatechin, and (epi)catechin→(epi)catechin isomers. Taking into account that quercetins and cyanidins account for more than 80% of antioxidants, it is logical to assume that these polyphenols might give protection to good-colored apples against skin burning.

Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties

BACKGROUND

Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate)) methods, and to correlate their TAC values with HPLC findings.

RESULTS

The order of TAC (mmol Trolox g(-1) fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC-quantified compounds, with the aid of the combined HPLC-CUPRAC method, accounted for 18.4-33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5-56.3% of flesh extracts, depending on apple variety.

CONCLUSION

In synthetic samples of apple antioxidants, the CUPRAC-TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel.