Phenolic compounds and antioxidant activity in red-fleshed apples

Fruit Sector Strategic Management: An Exploration of Agro-food Chain Actors’ Perception of Market Sustainability of Apple Innovation

The fresh fruit industry is a highly dynamic sector in the food market. Fresh fruit chain actors have to adapt to the changing market environment in order to face upcoming challenges. The objective of this study is to analyze the market sustainability of red-fleshed apples (RFA) by exploring consumers’ and fresh fruit industry experts’ and stakeholders’ opinions in Italy and New Zealand. The study was carried out in Italy and New Zealand from December 2018 to June 2019 including 778 consumers and 29 expert and stakeholder interviews. Results show a promising market potential of RFA. Innovative attributes and nutritional value of RFA are the most important factors that push consumers’ interest and willingness to buy RFA. New Zealand consumers and women show a higher appreciation of RFA. The nutritional value of the fruit can be a strategic marketing management attribute especially for health-conscious consumers. However, experts think the market for RFA will develop slowly, and will remain a niche product. Some stakeholders are skeptical about consumer RFA appreciation, and fear that RFA are too radical a novelty on the market. The RFA may be perceived as not natural. There is the need to coordinate food chain stakeholders’ management practices on RFA. This allows to mitigate risks, set food standards acceptable for all chain stakeholders, and make sustainable economic investment on innovation.

Phytochemical profiles, antioxidant, and antiproliferative activities of red-fleshed apple as affected by in vitro digestion

The aim of this study was to characterize the phenolic profiles in the extracts and digesta (after in vitro digestion) of different red-fleshed apple fruit parts and to assess the effects of digestion on the in vitro antioxidant capacity and antiproliferative activity. The main polyphenols were identified by UPLC-MS/MS and HPLC. Our results indicate that the digesta had less total phenolics, flavonoids, and anthocyanins, but more free phenolic acids, than the extracts. An analysis of the in vitro antioxidant capacity (including ABTS radical scavenging activity, DPPH radical-scavenging capacity, ferric reducing antioxidant power [FRAP], and cellular antioxidant activity [CAA]) revealed that the digestion decreased the ABTS, DPPH, and FRAP values, but increased the CAA values, relative to the corresponding values for extracts. These results suggest that the digestion improved the effectiveness of the phenolic substances. Moreover, our findings imply that the digestion promoted the antiproliferative activity of red-fleshed apple peels and flesh relative to the extracts. Future in vivo investigations are warranted based on the results of the current study. PRACTICAL APPLICATION: The effects of an in vitro digestion on the phenolic compounds as well as the antioxidative and antiproliferative activities of red-fleshed apple were evaluated. The resulting data may clarify the bioavailability of the polyphenols in red-fleshed apple and enable scientists and consumers to exploit natural polyphenols.

Involvement of MdUGT75B1 and MdUGT71B1 in flavonol galactoside/glucoside biosynthesis in apple fruit

Apple is rich in flavonol glycosides, which are believed to contribute to putative health benefits associated with apple consumption. Glycosylation, catalyzed by uridine diphospho-glycosyltransferases (UGTs), is the last step in flavonol biosynthesis, which confers molecular stability and solubility to the flavonol. In the present study, the involvement of two UGTs, MdUGT75B1 and MdUGT71B1, in flavonol biosynthesis in apple was investigated. The major flavonols are quercetin 3-O-glycosides, and UV-B and blue light treatment significantly enhanced the accumulation of quercetin 3-O-galactoside, quercetin 3-O-glucoside, and kaempferol 3-O-galactoside. Transcript levels of MdUGT75B1 and MdUGT71B1 in fruit subjected to different treatments were correlated well with flavonol accumulation. MdUGT75B1 showed flavonol-specific activity with a preference for UDP-galactose as the sugar donor, while MdUGT71B1 using UDP-glucose exhibited a wider substrate acceptance. Thus, MdUGT75B1 and MdUGT71B1 are key UGTs involved in flavonol biosynthesis and may have important roles in regulating accumulation of these health-promoting bioactive compounds in apple.

Phytochemical profiles, antioxidant, and antiproliferative activities of four red-fleshed apple varieties in China

Red-fleshed apples are preferred because of their high content of phenolics and antioxidants. In this study, the phenolic characteristics, antioxidant properties, and antihuman cancer cell properties of the four hybrids of Malus sieversii f. niedzwetzkyana (Ledeb.) M. Roem were analyzed. In addition, the antioxidant and anti-proliferation properties of these apples were measured. Compared to "Fuji" apples, the red-fleshed apples were rich in phenolic and flavonoid chemicals, ranging from 1.5- to 2.6-fold and 1.4- to 2.4-fold, respectively. In all antioxidant methods (DPPH radical-scavenging capacity, ABTS radical scavenging activity, ferric reducing antioxidant power, and cell antioxidant capacity), "A38" obtained the highest antioxidant value, whereas "Fuji" got the lowest antioxidant value. The IC₅₀ values ranged from 33.44 ("A38") to 73.36 mg/mL ("Fuji") for MCF-7 and 20.94 ("A38") to 39.39 mg/mL ("Fuji") for MAD-MB-231. The red-fleshed "A38" and "Meihong" exhibited higher antioxidant and antiproliferative activities in vitro because of the higher levels of phenolics, and the higher potential for development and utilization value. PRACTICAL APPLICATION: The phenolic compounds, antioxidant activity, and antiproliferative activity in vitro of four red-fleshed apple cultivars and one white-fleshed apple cultivar were compared in this study. This information should assist to give a reasonable evaluation for scientists to breed new cultivars with high phenolics and to exploit the natural polyphenol.

Comparative study on the antioxidant activities of ten common flower teas from China

Flower teas are widely consumed across the world because of their beneficial health effects. The antioxidant activities of methanol extracts from ten common flower teas in China were evaluated using four antioxidant assays. The total phenolic (TPCs) and total flavonoid contents (TFCs) were also investigated. Most of these flower teas exhibited potent antioxidant effects, of which rosae rugosae flos exerted the strongest antioxidant effects in four assays. Rosae rugosae flos also exerted the highest TPC, while fragrans showed the highest TFC. Correction analysis indicated that phenolics play a key role in the antioxidant effect of flower teas, while flavonoids were poorly correlated with antioxidant activity. The results supported the consumption of flower teas as functional foods and their application as sources of natural antioxidants in the food industry.

Enhanced stability of red-fleshed apple anthocyanins by copigmentation and encapsulation

BACKGROUND

Red-fleshed apples are a great source of natural colorants and functional food ingredients because of their high anthocyanin content. Generally, anthocyanins are highly unstable after extraction, which limits their wide applications in the food and pharmaceutical industries. This study was aimed at investigating the effects of combining copigmentation with encapsulation on the stability of anthocyanins from red-fleshed apples. In this study, red-fleshed apple anthocyanins were copigmented with caffeic acid, and then the copigmented complexes were encapsulated using gum arabic and maltodextrin using spray drying and freeze drying.

RESULTS

All anthocyanin microcapsules had high encapsulation efficiencies ranging from 93.84 to 96.85% with mean hydrodynamic diameter smaller than 350 nm. After heating at 80 °C for 2 h, the dispersions of microencapsulated anthocyanins with copigments exhibited the highest absorbance values at λ_max (515 nm) (P < 0.05). Light stability experiments demonstrated that the half-life of the red-fleshed apple anthocyanins increased from 5 to 12 days after being treated with copigmentation and encapsulation. The drying methods (spray/freeze drying) did not significantly influence the stability of the microencapsulated anthocyanins.

CONCLUSIONS

Applying copigmentation and spray-drying encapsulation in tandem has great potential for enhancing the stability of red-fleshed apple anthocyanins. Thus, such anthocyanins with enhanced stability may be increasingly used in the food and pharmaceutical industries as value-added natural food pigments. © 2018 Society of Chemical Industry.

Variability in Catechin and Rutin Contents and Their Antioxidant Potential in Diverse Apple Genotypes

Catechins and rutin are among the main metabolites found in apple fruit. Sixty apple genotypes, harvested in 2016 and 2017, were analyzed for their phenolic content and antioxidant activity. The HPLC analysis showed that the catechin concentration ranged from 109.98 to 5290.47 µg/g, and the rutin concentration ranged from 12.136 to 483.89 µg/g of apple fruit. The level of DPPH activity ranged from 9.04% to 77.57%, and almost half of the 15 genotypes showed below 30–40% DPPH activity. The apple genotypes ‘Lal Ambri’, ‘Green Sleeves’, and ‘Mallus floribunda’ showed the highest DPPH activity of between 70% and 80%, while ‘Schlomit’, ‘Luxtons Fortune’, ‘Mayaan’, ‘Ananas Retrine’, and ‘Chaubatia ambrose’ showed the lowest ferric reducing antioxidant power (FRAP) activity (0.02–0.09%). Statistical analysis showed a correlation between DPPH activity and catechin content (r = 0.7348) and rutin content (r = 0.1442). Regarding antioxidant activity, fractionated samples of apple genotypes revealed significant activity comparable to that of ascorbic acid. There was also a consistent trend for FRAP activity among all apple genotypes and a significant positive correlation between FRAP activity and rutin content (r = 0.244). Thus, this study reveals a significant variation in antioxidant potential among apple genotypes. This data could be useful for the development of new apple varieties with added phytochemicals by conventional and modern breeders.

Phenolic compounds and antioxidant activity in red- and in green-fleshed kiwifruits

Red-fleshed kiwifruits are receiving increasing attention because of their high phenolic contents. However, detailed information on their phenolic compounds and antioxidant capacities remains scarce. Here, six red-fleshed and six green-fleshed kiwifruits were investigated to determine their contents of phenolic compounds and their antioxidant capacities. The results showed chlorogenic acid, p-coumaric acid and ferulic acid were the main phenolic compounds found in kiwifruit. Most of red-fleshed kiwifruits contain higher amounts of total phenolics and anthocyanins, as well as higher activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). Moreover, they exhibited stronger antioxidant capacities than green-fleshed kiwifruits in ABTS, DPPH and FRAP assays. Furthermore, the reactive oxygen species (ROS) inhibition assay showed the phenolics extracted from red-fleshed kiwifruit can better protect tobacco leaves against hydrogen peroxide (H2O2)-induced oxidative damage. This is because of their abundant anthocyanins which in vitro contribute more to H2O2 scavenging than the other phenolic compounds. Based on these findings, it is fair to conclude the red-fleshed kiwifruits are promising sources of antioxidants in human nutrition.

Extrusion of apple pomace increases antioxidant activity upon in vitro digestion

Apple pomace, a by-product of juice production, is a high-fibre, high-polyphenol functional food ingredient.

Seasonal Variability of the Phytochemical Composition of New Red-Fleshed Apple Varieties Compared with Traditional and New White-Fleshed Varieties

The main objective of this study was to evaluate the impact of the season on the apple phytochemical composition (phenolic compounds, triterpenes, and organic and ascorbic acids). For this proposal, four red-fleshed and five white-fleshed apple varieties from two consecutive seasons (2015 and 2016) were studied. A significant interaction with the season in some compounds was observed. The total phenolic content in the apple flesh from 2015 was higher than that from 2016 probably related with the lower rainfall during the harvest period in 2015 that could have favored hydric stress in the apple trees. The impact of the season on the apple skin was different. The 2016 season was characterized by higher maximum and minimum temperatures resulting in a higher content of flavonols, triterpenes, and organic acids. Anthocyanin concentration in both the flesh and skin of the red-fleshed apples showed no clear relationship to the season, and each variety showed an individual pattern.

Preparative separation of phloridzin from apple leaves using macroporous resins followed by preparative high-performance liquid chromatography

Phloridzin is one of the major phenolic compounds in apple and has been widely used in medicine for a long time due to its significant biomedical activities. In this article, macroporous resin was used for purification of phloridzin from apple leaves. The HPD-300 resin was selected for the enrichement of phloridzin according to its high adsorption and desorption capacities. The adsorption kinetics and isotherms were constructed on the HPD-300 resin and fitted well to the pseudo-second-order kinetic model and Langmuir model, respectively. Dynamic adsorption and desorption tests were performed on the column packed with HPD-300 resin to optimize the operating parameters. After one round treatment with HPD-300 resin, the purity of phloridzin in the product increased from 11.4 to 50.1% with a recovery yield of 79.3%. Subsequently, preparative high-performance liquid chromatography was employed for the purification of phloridzin. The purity of phloridzin could reach above 98% after further recrystallization with a recovery yield of 75.8%.

Nutritional characterization of apple as a function of genotype

Twenty two apple cultivars grown in Himachal Pradesh, India were harvested at commercial maturity and analysed for different physical (fruit weight, fruit dimensions, firmness, color) and nutritional attributes (ascorbic acid, antioxidant activity, total carotenoid, sugars, organic acids, phenolic compounds and minerals). Cultivar 'Oregon Spur II' was found to have maximum fruit size and weight while the least was observed for cultivar 'Starkrimson'. Quantitative differences were found in the nutritional profile among the cultivars with respect to all the above attributes. The ascorbic acid content ranged between 19.38 mg 100 g^-1 ('Well Spur') and 32.08 mg 100 g^-1 ('Starkrimson') while the antioxidant activity varied between 2.64 μmol Trolox equivalent g^-1 ('Granny Smith') and 13.20 μmol Trolox equivalent g^-1 ('Silver Spur'). The highest total carotenoid was found in 'Red Chief' (147.06 mg kg^-1) while in 'Early Red-I' the total carotenoid was only 29.03 mg kg^-1. HPLC analysis for individual sugars, organic acids and phenolic compounds was carried out. Fructose (average 50.79 g L^-1) was the most abundant sugar. Malic acid (average 6.03 mg L^-1) predominated among the individual organic acids. Potassium (average 795.14 mg 100 g^-1) and iron (average 2.04 µg g^-1) were the predominant macro and micro elements, respectively. Chlorogenic acid was the major constituent among phenolic compounds.

Variation in Phenolic Content, Profile, and Antioxidant Activity of Seeds among Different Paeonia ostii Cultivated Populations in China

The purpose of this study was to analyze the phenolic profiles of seeds from fifteen Paeonia ostii cultivated populations in China and identify their relationship with antioxidant activities and associated environmental factors. Thirteen individual phenolic compounds were quantitatively determined by HPLC, and (+)-catechin was the most abundant phenolic compound in the seeds. Correlation analysis showed that phenolics were the most effective antioxidant compound class by evaluating DPPH, ABTS, and hydroxyl radical scavenging activities as well as ferric reducing antioxidant power. Latitude and annual rainfall had significant effects on the contents of many phenolic compounds, and elevation was only significantly correlated with gallic acid content. Within fifteen P. ostii cultivated populations, the seeds of Tongling population exhibited the highest phenolic contents and strongest antioxidant activities. These results suggest that Tongling population has a relatively high utilization value and a potential for sources of natural antioxidants.

Biochemical Profile of Heritage and Modern Apple Cultivars and Application of Machine Learning Methods To Predict Usage, Age, and Harvest Season

The present study represents the first major attempt to characterize the biochemical profile in different tissues of a large selection of apple cultivars sourced from the United Kingdom's National Fruit Collection comprising dessert, ornamental, cider, and culinary apples. Furthermore, advanced machine learning methods were applied with the objective to identify whether the phenolic and sugar composition of an apple cultivar could be used as a biomarker fingerprint to differentiate between heritage and mainstream commercial cultivars as well as govern the separation among primary usage groups and harvest season. A prediction accuracy of >90% was achieved with the random forest method for all three models. The results highlighted the extraordinary phytochemical potency and unique profile of some heritage, cider, and ornamental apple cultivars, especially in comparison to more mainstream apple cultivars. Therefore, these findings could guide future cultivar selection on the basis of health-promoting phytochemical content.

Phytochemical Profiles of New Red-Fleshed Apple Varieties Compared with Traditional and New White-Fleshed Varieties

This study is an exhaustive chemical characterization of the phenolic compounds, triterpenes, and organic and ascorbic acids in red-fleshed apple varieties obtained by different breeding programs and using five traditional and new white-fleshed apple cultivars as reference. To carry out these analyses, solid-liquid extraction (SLE) and ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) were used. The results showed that the red-fleshed apples contained, in either the flesh or peel, higher amounts of phenolic acids (chlorogenic acid), anthocyanins (cyanidin-3-O-galactoside), dihydrochalcones (phloretin xylosyl glucoside), and organic acids (malic acid) but a lower amount of flavan-3-ols than the white-fleshed apples. These quantitative differences could be related to an up-regulation of anthocyanins, dihydrochalcones, and malic acid and a down-regulation of flavan-3-ols (anthocyanin precursors) in both the flesh and peel of the red-fleshed apple varieties. The reported results should be considered preliminary because the complete phytochemical characterization of the red-fleshed apple cultivars will be extended to consecutive harvest seasons.

Analysis of Polyphenolic Compounds in Extracts from Leaves of Some Malus domestica Cultivars: Antiradical and Antimicrobial Analysis of These Extracts

In this study, methanol, ethyl acetate, water extracts, and precipitate were obtained from leaves of Malus domestica cultivars: Golden delicious, Jonagold, Elstar, Ligol, and Mutsu. Antiradical activity of these extracts was measured using the ABTS^+∙ radical, and antimicrobial activity was measured with the disk-diffusion method. Phenolic compounds were measured with the colorimetric method and identified with high performance liquid chromatography (HPLC). The highest antiradical activity was observed for the Jonagold variety, and in particular strong activity was noted for ethyl acetate extracts. Antimicrobial activity was observed against strains of Staphylococcus aureus, Enterococcus faecalis, and the fungus Candida glabrata. Particularly susceptible to the extracts activity appeared to be Staphylococcus aureus, but the growth of Candida glabrata was inhibited in the presence of ethyl acetate extracts. With the HPLC method we identified a high amount of phloridzin (above 500 mg per g of ethyl acetate extracts), lower amounts of hyperoside, isoquercitrin, and quercitrin, and traces of p-hydroxybenzoic and chlorogenic acids. The contribution of phloridzin to antiradical activity of methanol and ethyl acetate extracts was very high (above 90%). In water extract the contribution of phloridzin was between 38.9 and 55.2%, chlorogenic acid 22.7 and 36.1%, and hyperoside 12.2 and 13.3%.

Phenolic Profiles and Antioxidant Activity of Lotus Root Varieties

Lotus root attracts increasing attention mainly because of its phenolic compounds known as natural antioxidants. Its thirteen varieties were systematically analyzed on the content, distribution, composition and antioxidant activity of phenolic compounds for a better understanding of this aquatic vegetable. The respective mean contents of total phenolics in their flesh, peel and nodes were 1.81, 4.30 and 7.35 mg gallic acid equivalents (GAE)/g fresh weight (FW), and those of total flavonoids were 3.35, 7.69 and 15.58 mg rutin equivalents/g FW. The phenolic composition determined by a high-performance liquid chromatography method varied significantly among varieties and parts. The phenolics of flesh were mainly composed of gallocatechin and catechin; those of peel and node were mainly composed of gallocatechin, gallic acid, catechin and epicatechin. The antioxidant activities of phenolic extracts in increasing order were flesh, peel and node; their mean concentrations for 50% inhibition of 2,2-diphenyl-1-picrylhydrazyl radical were 46.00, 26.43 and 21.72 µg GAE/mL, and their mean values representing ferric reducing antioxidant power were 75.91, 87.66 and 100.43 µg Trolox equivalents/100 µg GAE, respectively. “Zoumayang”, “Baheou”, “No. 5 elian” and “Guixi Fuou” were the hierarchically clustered varieties with relatively higher phenolic content and stronger antioxidant activity as compared with the others. Especially, their nodes and peels are promising sources of antioxidants for human nutrition.

The Changes in Color, Soluble Sugars, Organic Acids, Anthocyanins and Aroma Components in "Starkrimson" during the Ripening Period in China

"Starkrimson" is a traditional apple cultivar that was developed a long time ago and was widely cultivated in the arid region of the northern Wei River of China. However, little information regarding the quality characteristics of "Starkrimson" fruit has been reported in this area. To elucidate these characteristics, the color, soluble sugars, organic acids, anthocyanins and aroma components were measured during the ripening period through the use of high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The results indicated that the changes in anthocyanin contents took place later than the changes in the Commission International Eclairage (CIE) parameters. Meanwhile, cyanidin 3-galactoside (cy3-gal), fructose, sucrose, glucose and malic acid were the primary organic compounds, and 1-butanol-2-methyl-acetate, 2-hexenal and 1-hexanol were the most abundant aroma components in the skin. Furthermore, rapidly changing soluble sugars and organic acid synchronization took place in the early ripening period, while rapidly changing aroma components occurred later, on the basis of fresh weight. This result suggested that the production of aroma components might be a useful index of apple maturity.

Phenol profiles and antioxidant capacities of Bistort Rhizoma (Polygonum bistorta L.) extracts

This work demonstrated that the crude Bistort Rhizoma (BR) extracts exhibit an antioxidant effectiveness, which significantly correlated with the content of TP, showing that TP may be responsible for the antioxidant activity of BR extract.