Phenolic compounds and antioxidant activity in fruits of six Diospyros kaki genotypes

Fruits from six persimmon (Diospyros kaki) genotypes were compared for phenolic compounds and their antioxidant capacity in this study. The results showed that all fruit extracts exhibited strong antioxidant activities, which generally correlated positively with the total phenolic contents, total flavonoid contents, and total flavanol contents. High-performance liquid chromatography (HPLC) analysis revealed that gallic acid and quercetin were the major phenolic components in the fruit extracts of six D. kaki genotypes. Hierarchical cluster analysis showed that wild genotype D. kaki. var. Silvestris Makino belongs to the group with high phenolic content and strong antioxidant ability, while astringent genotypes D. kaki. cv. Xiuningbianshi and D. kaki. cv. Zhouqumomoshi are arranged in one group characterized by moderate phenolic content and antioxidant capacity, the non-astringent genotypes D. kaki. cv. Zenjimaru, D. kaki. cv. Jiro and the astringent genotype D. kaki. cv. Xingyangshuishi belongs to the third group because of their low phenolic content and weak antioxidant activity. On the basis of the results obtained, the persimmon fruit could be a potential source of natural antioxidants for food and pharmaceutical applications.     

Persimmon Pectinmethylesterase: Extraction and Variation during Ripening

The optimum conditions for the extraction of pectinmethylesterase (PME) from persimmon fruit (Diospyros kaki cv. Taubaté) were found to be: 1.6M NaCl + 1% (v/v) Triton X-100 + 5% (w/v) bovine serum albumin (BSA) for astringent fruit and 0.2M NaCl for nonastringent fruit. During ripening with ethephon, PME showed a close variation with respiration up to the climacteric peak when fruits became soft and nonastringent. Untreated astringent fruits showed little variation in either respiration or PME activity.     

Deastringency of Persimmon Fruits by Creating a Modified Atmosphere in Polyethylene Bags

Removal of astringency from persimmons (Diospyros kaki L.) was achieved by enclosing the fruits in air-evacuated polyethylene bags. Reducing the initial in-package air volume created anaerobic conditions by decreasing the O₂ level. Induced anaerobic respiration in-creased the levels of CO₂. acetaldehyde and ethanol, in the atmosphere surrounding the fruit and thereby triggered the deastringency process. Deastringency in air-evacuated polyethylene bags was attained within3–4 days at 20°C. Following the deastringency, the fruits in the bags maintained a high quality and firmness during cold storage and shelf life. Good flavor was maintained for about 10 days at 20°C, but thereafter off-flavor developed due to accumulation of volatiles.     

Mechanical properties of fruit-cuticular membranes isolated from 27 cultivars of Diospyros kaki Thunb.

Fruit cuticular membranes (CMs) were isolated from 27 cultivars of Diospyros kaki Thunb., and relationships among their chemical compositions, densities and mechanical properties were analysed. Wide cultivar dependency was observed in both chemical compositions and mechanical properties, however, astringency did not show clear correlation with them. Densities of the CMs showed significant positive correlation with maximum stress and elastic modulus, but negative correlation with maximum strain. Positive correlations were also observed in elastic modulus-polysaccharide content and maximum strain-polysaccharide content, and negative correlation in elastic modulus-cutin content on a weight over unit area (μg/cm²) basis. The integration of densities of fruit CMs and their chemical constituents may explain the mechanical properties which are specific to each cultivar of D. kaki fruit.     

Volatile Compounds from the Mesocarp of Persimmons

Steam volatile fractions from astringent and nonastringent persimmons (Diospyros kaki L.) and the native American persimmon (D. virginiana L.) were analyzed by GC and GC/MS. Bomyl acetate and (E)-2-hexenal were major components from all cultivars. Minor constituents included (E)-2-hexenol, phenylacetaldehyde, phenylethyl acetate, borneol, benzothiazole, neryl acetate, palmitic acid and two saturated normal hydrocarbons (C₂₃H₄₈ and C₂₅H₅2). From threshold values and concentrations, (E)-2-hexenal and bornyl acetate probably are major contributors of persimmon aroma.     

Antimicrobial activity of catechol isolated from Diospyros kaki Thunb. roots and its derivatives toward intestinal bacteria

The growth-inhibiting activities of the methanol extract of Diospyros kaki Thunb. roots were examined on the growth of Bifidobacterium breve, B. longum, Clostridium difficile, Clostridium perfringes, Escherichia coli, and Lactobacillus casei. In addition, the biologically active component of D. kaki roots was purified using silica gel column chromatography and HPLC. The active component was characterised as catechol by spectroscopic analyses. The antimicrobial activity of the isolated catechol varied according to the dose and bacterial strains tested. Catechol significantly (++++) inhibited the growth of C. perfringens at 2.0 mg/disc, and moderately (++) inhibited its growth at 0.25 mg/disc. At a dose of 5.0 mg/disc, catechol significantly inhibited the growth of C. difficile and moderately inhibited the growth of E. coli. However, this isolate did not inhibit the growth of bifidobacteria and lactobacilli. When various functional groups were added to the catechol, selective growth-inhibiting activity against harmful intestinal bacteria was observed in response to treatment with low concentrations. Taken together, these findings indicate that D. kaki root-isolated catechol and its derivatives (4-nitrocatechol, 4-tert-butylcatechol, tetrabromocatechol) could be useful as preventive agents against diseases caused by harmful intestinal bacteria.     

Sulphated modification of a polysaccharide obtained from fresh persimmon (Diospyros kaki L.) fruit and antioxidant activities of the sulphated derivatives

Free radicals and other reactive oxygen species (ROS) are believed to play significant roles in ageing as well as in a number of degenerative or pathological diseases. This paper reports the preparation, characterisation and potential antioxidant activity of a type of chemically sulphated polysaccharide isolated from fresh persimmon (Diospyros kaki L.) fruit. Three sulphated derivatives with variable degrees of substitution (0.8, 1.7 and 2.5) were obtained by the chlorosulphonic acid–pyridine method. The sulphated derivatives all showed dose-dependent reducing power and free radical scavenging effect of 1,1-dipheny-l-2-picrylhydrazyl, superoxide anion and hydroxyl. Our results showed that the sulphated modification of polysaccharides significantly increased their antioxidant activities and may be an effective way to prepare these valuable derivatives.     

Classification of juices and fermented beverages made from unripe,ripe and senescent apples based on the aromatic profile using chemometrics

The aim of this study was to assess differences between apple juices and fermented apple beverages elaborated with fruits from different varieties and at different ripening stages in the aroma profile by using chemometrics. Ripening influenced the aroma composition of the apple juice and fermented apple. For all varieties, senescent fruits provided more aromatic fermented apple beverages. However, no significant difference was noticed in samples made of senescent or ripe fruits of the Lisgala variety. Regarding the juices, ripe Gala apple had the highest total aroma concentration. Ethanal was the major compound identified in all the samples, with values between 11.83 mg/L (unripe Lisgala juice) and 81.05 mg/L (ripe Gala juice). 3-Methyl-1-butanol was the major compound identified in the fermented juices. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied and classified the juices and fermented juices based on physicochemical and aroma profile, demonstrating their applicability as tools to monitor the quality of apple-based products.     

Inhibitory effect of the ethyl acetate fraction from astringent persimmon on H2O2-induced oxidative stress in HepG2 cells

Persimmon cv. Sangjudungsi (Diospyros kaki Thunb.) is a major astringent cultivar in Korea. A phenolic extract of cv. Sangjudungsi was obtained using acetone with homogenization, then sequentially fractionated into n-hexane, chloroform, ethyl acetate, n-butanol, and water fractions. These 5 fractions were used to evaluate levels of total phenolics and total flavonoids, and the antioxidant capacities, and to investigate whether the fractions protected human hepatoma HepG2 cells from deleterious oxidative stress. The ethyl acetate fraction had the highest levels of total phenolics and total flavonoids, and the greatest antioxidant capacity. Under oxidative stress caused by H₂O₂, the ethyl acetate fraction at non-toxic concentrations significantly (p<0.05) restored the viability of HepG2 cells in a dose-dependent manner, compared with a control. The ethyl acetate fraction also alleviated intracellular oxidative stress, possibly due to effective antioxidant activities in cells. Astringent persimmons are a good source of antioxidants for reduction of oxidative stress.     

Phytochemicals,vitamin C and sugar content of Thai wild fruits

The objective of the present study was to generate information about the potential health-enhancing properties of selected Thai wild fruits. Nineteen varieties of wild fruits, collected from the natural forest in north-eastern Thailand, were analysed for phytochemicals, anti-oxidant activity, vitamin C and sugar content. The results showed that Diospyros decandra Lour. exhibited the highest content of total phenolic compounds (215 mg GAE/g) and total flavonoid content (187 mg RE/g). Terminalia chebula Retz. had higher anti-oxidant activities than other fruits, as measured by 1,1-diphenyl-2-picrylhydrazyl radical scavenging (99% inhibition) and ferric reducing/anti-oxidant power assays (63 mmol FeSO₄/g). The sum of sugars (sucrose, glucose, fructose and galactose) ranged from 33 to 430 mg/g fresh weight, being dominated by glucose (ranging from 7.5 to 244 mg/g) and fructose (ranging from 5.3 to 193 mg/g). The highest content of vitamin C was found in Phyllanthus emblica Linn. (2.2 mg/g). Thai wild fruits, which were investigated in this study, have been shown to be a novel rich source of phytochemicals.     

Volatile constituents of exotic fruits from Brazil

Flavor is one of the main attributes of foods and is given by a combination of volatile molecules present in the matrix. This paper reviews the general characteristics and uses and focuses on the volatile composition of selected Brazilian exotic fruits: Brazilian cherry (Eugenia uniflora), acerola (Malpighia glabra L., Malpighia punicifolia L., Malpighia emarginata DC.), jackfruit (Artocarpus heterophyllus), starfruit (Averrhoa carambola) and fruits from the genera Annona (cherimoya, soursop, sugar apple etc.) and fruits from the genera Spondias (S. purpurea, S. mombin and S. tuberosa). This is information important for flavor industry, which use different aroma compounds for the formulation of fragrances and flavorings to be used in foods, cosmetics and perfumes.     

Effect of aminoethoxyvinylglycine and low-pressure storage on the post-storage production of aroma volatiles by Golden Delicious apples

Golden Delicious apple fruits untreated (control) or treated pre-harvest with the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) were stored at 2°C under either ambient pressure or low pressure (6.7 kPa; LPS). The production of aroma volatiles during post-storage periods at 20°C was measured on fruits stored for 3, 5, 7 and 9 months. Aroma production of AVG- or LPS-treated fruits immediately after storage was considerably lower. However, after 14 days at 20°C, aroma production almost reached values for control fruits (AVG fruits had to be treated with 50 μl C₂H₄ litre^?1). After the longer storage this effect of a post-storage period at 20°C declined gradually and finally was almost absent. Only a post-storage period at 2°C in a normal atmosphere followed by a period at 20°C was now able to partially revive long-stored fruits from this ‘residual’ effect of AVG or LPS. It is suggested that changes in the sensitivity of fruits to C₂H₄ are responsible for the observed decline in aroma production.     

Aroma biogenesis and distribution between olive pulps and seeds with identification of aroma trends among cultivars

The two constitutive parts of four cultivars (Arbequina, Picual, Local and Manzanilla de Sevilla) grown in Spain were separately analysed in order to establish the role of pulp and seed in the biogenesis of extra virgin olive oil (EVOO) aroma through the lipoxygenase (LOX) pathway. C6 and C5 volatile compounds responsible of EVOO aroma were produced by endogenous enzymes in both parts of olive fruits and the differences can be attributed to different enzymes distribution in pulp and seed. According to results, C6 and C5 volatile compounds have mainly their biogenesis in pulp (80–90%) vs. seed (20–10%), independently of the cultivar considered. A linear discriminant analysis was used to establish discriminant aroma compounds between pulp and seed related to the maturity index. A decrease in trans-2-hexen-1-al and an increase in 1-hexanol with ripeness were observed independently of the cultivar considered. Finally, Partial Least Squares (PLS) regression analysis between pulp and seed aroma compounds allowed to establish those volatile compounds that better describe each cultivar.     

Effect of 1-methylcyclopropene on ripening of postharvest persimmon (Diospyros kaki L.) fruit

Postharvest persimmon fruit (Diospyros kaki L. cv. Qiandaowuhe) was stored at 20 °C after being exposed to 3 μl l⁻¹ 1-methylcyclopropene (1-MCP) for 6 h or not (control). Several parameters (firmness, respiration and ethylene production, pectic substances and cell wall hydrolysis enzymes activities) were examined to determine the efficacy of 1-MCP treatment in delaying persimmon fruit ripening. Results showed that ‘Qiandaowuhe’ persimmon fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak CO₂ production and ethylene production was observed on the fourth day. Fruit softening was accompanied by a progressive increase in water-soluble pectic substances (WSP) and a progressive decrease in chelator-soluble pectic substances (CSP) and alkali-soluble pectic substances (ASP). The activities of pectinmethylesterase (PME) and polygalacturonase (PG) started increasing sharply and reached a maximal value on days 4 and 6, respectively, and then decreased slowly. 1-MCP treatment delayed the onset of climacteric ethylene production and respiration in persimmon fruit, and also significantly retarded the activities of PME and PG during ripening at 20 °C. Consistent with the activity trends of cell wall hydrolysis enzymes, 1-MCP treatment also delayed the depolymerization of CSP and ASP and reduced the increase of WSP compared with the control fruit. Thus, application of 1-MCP can greatly extend the postharvest life of ‘Qiandaowuhe’ persimmon fruit.     

Selected primary and secondary metabolites in fresh persimmon (Diospyros kaki Thunb.): A review of analytical methods and current knowledge of fruit composition and health benefits

Diospyros kaki Thunb. (Ebenaceae) is a widely cultivated tree species in some countries of Asia, while in other continents persimmons are mostly considered “exotic” fruits. Peculiar characteristics of this species are a complex sex expression, parthenocarpy and fruit astringency at harvest time, associated with a different composition in polymerized flavan-3-ols. Analytical methods for determining sugars, vitamin C, carotenoids and polyphenols in persimmons were critically reviewed in order to evaluate the overall significance of literature results; the nutritional and nutraceutical properties, together with the health benefits of both astringent and non astringent cultivars, were also overviewed. To these aims, the available literature from the last twenty years and the most important formerly published papers were investigated using SciFinder^®, Elsevier SciVerse, AGRIS, and PubMed search engines. Persimmons resulted rich in sugars (about 12.5 g/100 g FW), being fructose, glucose and sucrose the major components, and in total vitamin C, for which 100-150 g of fresh persimmon supplies the recommended daily amount. Astringent varieties supply higher amounts of sugars than nonastringent ones; conversely, higher concentrations of total vitamin C were found in nonastringent cultivars. The main carotenoid components are ??-cryptoxantin (193 ??g/100 g FW), ??,??-carotene (113 ??g/100 g FW) and ??,??-carotene (30 ??g/100 g FW). Persimmons are also a good source of polyphenolic compounds such as p-coumaric acid, catechin, epicatechin, epigallo catechin, and condensed proanthocyanidins. This chemical composition, together with in vivo and in vitro studies, suggests a relevant role of persimmon in the protection against free radicals and in the prevention of some human diseases.     

Identification of yeast and acetic acid bacteria isolated from the fermentation and acetification of persimmon (Diospyros kaki)

Persimmon (Diospyros kaki) is a seasonal fruit with important health benefits. In this study, persimmon use in wine and condiment production was investigated using molecular methods to identify the yeast and acetic acid bacteria (AAB) isolated from the alcoholic fermentation and acetification of the fruit. Alcoholic fermentation was allowed to occur either spontaneously, or by inoculation with a commercial Saccharomyces cerevisiae wine strain, while acetification was always spontaneous; all these processes were performed in triplicates. Non-Saccharomyces yeast species were particularly abundant during the initial and mid-alcoholic fermentation stages, but S. cerevisiae became dominant toward the end of these processes. During spontaneous fermentation, S. cerevisiae Sc1 was the predominant strain isolated throughout, while the commercial strain of S. cerevisiae was the most common strain isolated from the inoculated fermentations. The main non-Saccharomyces strains isolated included Pichia guilliermondii, Hanseniaspora uvarum, Zygosaccharomyces florentinus and Cryptococcus sp. A distinct succession of AAB was observed during the acetification process. Acetobacter malorun was abundant during the initial and mid-stages, while Gluconacetobacter saccharivorans was the main species during the final stages of these acetifications. Four additional AAB species, Acetobacter pasteurianus, Acetobacter syzygii, Gluconacetobacter intermedius and Gluconacetobacter europaeus, were also detected. We observed 28 different AAB genotypes, though only 6 of these were present in high numbers (between 25%–60%), resulting in a high biodiversity index.     

Physicochemical Characterization of Pure Persimmon Juice: Nutritional Quality and Food Acceptability

Technological process for production of non‐astringent persimmon (Diospyros kaki Thunb. cv. “Rojo Brillante”) juice was described. The degree of fruit ripening expressed as color index (CI) varied between 12.37 and 16.33. Persimmon juice was characterized by determining physicochemical quality parameters as yield, total soluble solids (TSS), pH, titratable acidity (TA), organic acids, and main sugars. A thermal treatment of 90 ºC for 10 s was effective in controlling naturally occurring microorganisms for at least 105 d of storage without significantly affecting production of soluble brown pigments (BPs) and 5‐hydroxymethyl furfural (5‐HMF), total phenolic compounds (TPC), antioxidant capacity and acceptability of juice by panelists. Storage time affected all and each of the above parameters, reducing BPs, TPC and antioxidant capacity but increasing 5‐HMF content. Refrigerated storage enhanced the acceptability of the juices. This information may be used by the juice industry as a starting point for production of pure persimmon juices.     

Enzymatic carotenoid degradation and aroma formation in nectarines (Prunus persica)

C-13 norisoprenoids such as β-ionone, 3 hydroxy-β-ionone, and 3 hydroxy-5,6-epoxy-β-ionone are important carotenoid related aroma compounds in fruits.Apart from chemical degradation (photo-oxygenation, (auto)oxidation, thermal degradation), enzymatic cleavage is an important flavor formation pathway [Enzell, C. (1985). Biodegradation of carotenoids – an important route to aroma compounds. Pure and Applied Chemistry, 57(5), 693–700; Winterhalter, P., & Rouseff, R. (Eds.). (2001). Carotenoid-derived aroma compounds. ACS symposium series 802, Washington, DC: American Chemical Society (ISBN 0-8412-3729-8)]. In nectarines, the content of carotenoid degradation products depends on the degree of maturity. In fully ripened fruit up to 40% of the aglycons are C-13 norisoprenoids [Aubert, C., Günata, Z., Ambid, C., & Baumes, R. (2003). Changes in physicochemical characteristics and volatile constituents of yellow- and white-fleshed nectarines during maturation and artificial ripening. Journal of Agriculture and Food Chemistry, 51(10), 3083–3091]. Regiospecific carotenoid cleavage enzymes have been shown to be involved in aroma formation in different plants and fruits [Bouvier, F., Suire, C., Mutterer, J., & Camara, B. (2003). Oxidative remodeling of chromoplast carotenoids: identification of the carotenoid dioxygenase CsCCD and CsZCD genes involved in crocus secondary metabolite biogenesis. Plant Cell, 15(1), 47–62; Fleischmann, P., Studer, K., & Winterhalter, P., (2002). Partial purification and kinetic characterization of a carotenoid cleavage enzyme from quince fruit (Cydonia oblonga). Journal of Agriculture and Food Chemistry, 50(6), 1677–1680; Fleischmann, P., Watanabe, N., & Winterhalter, P., (2003). Enzymatic carotenoid cleavage in star fruit (Averrhoa carambola). Phytochemistry, 63(2), 131–137; Schwartz, Qin & Zeevaart, 2001].This paper describes the isolation and partial characterization of carotenoid cleavage enzymes in nectarines, isolated from ripe skin of commercially available fruit. The enzyme is characterized by its kinetic parameters (v_max, K_m, time constant, temperature dependence, activation energy).     

基于电子鼻评价不同贮藏期蜜桔鲜榨汁品质的研究

为建立一种快速无损检测蜜桔鲜榨汁品质的方法,将宫川蜜桔(satsuma mandarins)置于20℃、相对湿度85%条件下贮藏,每3 d随机选取10个果实制成汁,利用PEN3电子鼻检测其香气,同时测定其主要品质指标并进行相关性分析。通过主成分分析(Principal Component Analysis,PCA)、线性判别分析(Linear Discriminant Analysis,LDA)对不同贮藏时间的蜜桔进行区分。结果显示:电子鼻传感器响应值与蜜桔鲜榨汁可溶性固形物含量和VC含量显著相关;线性判别分析能较好地区分出不同贮藏时间的蜜桔;负荷加载分析(Loading analysis)结果显示,传感器W1S(主要对甲烷灵敏)、W2S(对乙醇灵敏,也对部分芳香型化合物灵敏)和W2W(对芳香成分和有机硫化物灵敏)在蜜桔鲜榨汁品质评价中起主要作用。结果表明利用电子鼻技术有望实现对蜜桔鲜榨汁品质的快速无损检测。