Comparative analysis of volatile metabolites, quality and sensory attributes of Actinidia chinensis fruit

Comprehensive evaluation of twelve kiwifruit (Actinidia) varieties on the winemaking adaptability based on multi-criteria decision-making method

As one of the deep processing products of kiwifruit, kiwifruit wine (KW) has shown good commercial development prospects. In this paper, the wine-making adaptability and quality characteristics of 12 kiwifruit varieties with three pulp colors were systematically evaluated from the aspects of basic physicochemical, functional and sensory qualities. The results of the study showed that the ratio of sugar to acid of Hongyang wine was 0.81, which was significantly higher than other varieties. In terms of functional quality, the vitamin C content of Puyu wine was 214.43 mg/100 g, which was significantly higher than that of other varieties. Hongshi No.2 wine is the variety with the highest content of total polyphenols and flavonoid, the contents are 51.64 mg/100 g and 18.86 mg/100 g, respectively. The antioxidant activity of the wines in descending order was red-fleshed, yellow-fleshed and green-fleshed. The results of the color characterization showed that the brightness of all the wines was higher than 80, indicating that the KW were relatively clear and transparent. The result of artificial sensory evaluation showed that the Hongshi No.2 wine was more popular overall. Based on principal component analysis, optimal solution based ranking approach and gray relevance analysis models, Hongshi No.2 wine ranks first overall due to its rich nutritional content, sweet taste, and rich fruity aroma. This study involves the kiwifruit varieties with the largest planting area in the world, and the quality characteristics of their corresponding KW varieties were preliminary analyzed and compared. It provides a theoretical basis with strong pertinence and wide coverage for the production of various KW types, so as to contribute to the sustainable development of KW industry.

Melatonin/P34HB Films for Active Packaging: Optimizing Flavor Preservation and Quality of Honey Peaches During Storage

To address unpredictable flavor changes in postharvest peaches during storage, this study investigated the use of bioactive packaging with melatonin-infused P34HB films. Films with melatonin concentrations of 0%, 1%, 3%, and 5% were prepared using the extrusion casting method and applied to peach storage at room temperature. Comprehensive film properties were characterized, showing that melatonin minimally impacted the films' mechanical properties, including gas and water vapor permeability, but significantly increased film haze. Using GC-IMS, 30 organic compounds affecting peach flavor were effectively identified, including 8 aldehydes, 5 alcohols, 4 ketones, 12 esters, 1 pyrazine, 1 olefin, and 1 furan. Unpackaged, naturally ripening peaches served as a reference for assessing flavor and quality changes across various packaging groups during storage. The results indicated that the appearance of off-flavor organic compounds, such as ethanol produced by peach anaerobic respiration and complex esters, was the primary cause of flavor deterioration. The P34HB film with 1% melatonin most effectively preserved the original flavor and juiciness of peaches, highlighting its potential as an active packaging solution for fruit.

Analysis of Aroma Characteristics of 'Binzi' and 'Xiangguo' Apple-Ancient Cultivars in China

'Binzi' (BZ) (Malus domestica subsp. chinensis var. binzi Li Y.N.) and 'Xiangguo' (XG) (Malus domestica subsp. chinensis var. xiangguo Li Y.N.) are the ancient cultivars in China. The BZ fruits have a low-fragrant flavor on harvest day but a high-fragrant flavor after storage at room temperature, while the XG fruits have a stronger flavor when mature. 'Starking' (SK) and 'Golden Delicious' (GD) fruits have a rich flavor and are recognized by all countries in the world. However, information on the differences between ancient Chinese cultivars and Western apple cultivars in aroma compounds remains unknown. The apple fruits were collected for continuous two years. Aroma compounds in the skin and pulp of the fruits were detected at room temperature (20 ± 1 °C) during storage. The dynamics of VOCs in BZ and SK fruits were more similarly reflected in esters, while those of XG and GD fruits were reflected in aldehydes and alcohols. Ethyl 2-methylbutyrate, with an extremely low odor threshold, was the main source of typical apple flavor in SK, BZ, and XG fruits, while hexyl acetate was the source of the banana flavor in GD fruits. 6-methyl-5-hepten-2-one and β-damascenone were the important ketones produced in the later stage of storage, derived from the carotenoid metabolism pathway and providing a citrus and rose flavor to the four apple cultivars. SK had the highest number of characteristic aroma components, which were mainly derived from the amino acid metabolism pathway, providing fruits with a sweet and fruity flavor. Although the characteristic aroma components of GD were derived from the fatty acid metabolic pathway, the number of volatile esters was lower. Ethyl butyrate, derived from the saturated fatty acid metabolism, had the highest content in BZ, providing a pineapple flavor; the flavor of XG was mainly derived from ethyl 2-methylbutyrate, 6-methyl-5-hepten-2-one, and β-damascenone. Therefore, we suggest BZ and XG apples as the aroma-breeding material with which to enrich new cultivars' aroma components, derived from the fatty acid metabolism and carotenoid metabolism pathways, respectively.

Kiwifruit in the Omics Age: Advances in Genomics, Breeding, and Beyond

The kiwifruit, Actinidia genus, has emerged as a nutritionally rich and economically significant crop with a history rooted in China. This review paper examines the global journey of the kiwifruit, its genetic diversity, and the role of advanced breeding techniques in its cultivation and improvement. The expansion of kiwifruit cultivation from China to New Zealand, Italy, Chile and beyond, driven by the development of new cultivars and improved agricultural practices, is discussed, highlighting the fruit's high content of vitamins C, E, and K. The genetic resources within the Actinidia genus are reviewed, with emphasis on the potential of this diversity in breeding programs. The review provides extensive coverage to the application of modern omics technologies, including genomics, transcriptomics, proteomics, and metabolomics, which have revolutionized the understanding of the biology of kiwifruit and facilitated targeted breeding efforts. It examines both conventional breeding methods and modern approaches, like marker-assisted selection, genomic selection, mutation breeding, and the potential of CRISPR-Cas9 technology for precise trait enhancement. Special attention is paid to interspecific hybridization and cisgenesis as strategies for incorporating beneficial traits and developing superior kiwifruit varieties. This comprehensive synthesis not only sheds light on the current state of kiwifruit research and breeding, but also outlines the future directions and challenges in the field, underscoring the importance of integrating traditional and omics-based approaches to meet the demands of a changing global climate and market preferences.

Impact of must clarification treatments on chemical and sensory profiles of kiwifruit wine

This study examined the effect of various clarification treatments on the physicochemical properties, volatile compounds, and sensory attributes of kiwi wines produced from five different kiwifruit (Actinidia deliciosa) varieties. The degree of clarification had a minimal impact on physicochemical parameters, including the content of residual sugar, ethanol, volatile acid, titratable acidity (except for the kiwifruit variety 'Qinmei'), and the pH value. However, wines made from unclarified juices (muddy juice and pulp) displayed a higher glycerol content than those made from clarified juices. The cluster heat map and principal component analyses (PCA) demonstrated that kiwi wines produced from clarified kiwi juices possessed a higher ester content, whereas muddy juice and pulp wines contained elevated levels of higher alcohols. Quantitative descriptive analysis (QDA) indicated that clarified juice wines outperformed muddy juice and pulp wines in terms of purity, typicality, harmony, intensity, and freshness, with negligible differences in terms of palate acidity. Moreover, the clarified juice wines featured more characteristic kiwi wine aromas (kiwifruit, passionfruit, and pineapple) compared with that of the muddy juice and pulp wines, which exhibited an increased grassy flavour. Although the 100-NTU kiwifruit juice-fermented wine did not show an advantage in the cluster heat map and PCA, it presented better freshness, typicality, and intensity in the QDA, as well as a more passionfruit aroma. Based on the orthogonal partial least-squares discriminant analysis, A. deliciosa 'Xuxiang' was deemed to be the most suitable variety for vinification. This study provides crucial insights for enhancing the production of high-quality kiwi wine.

The effects of different rootstocks on aroma components, activities and genes expression of aroma-related enzymes in oriental melon fruit

Grafting is widely applied in the cultivation of melon. In this study, 'Qinmi No.1' (Cucumis melo L.(QG)) and 'Ribenxuesong' (Cucurbita maxima Duch. (RG)) were used as rootstocks for 'Qingxin Yangjiaocui' (Cucumis melo L.). The results showed that grafting with muskmelon rootstocks had no significant effect on fruit aroma, but grafting with pumpkin rootstocks significantly reduced the odor intensity and odor preference scores of melon fruits. Compared with the fruits from self-grafted plants (SG), four new aromatic volatiles with a sweet smell were detected, the alcohol dehydrogenase (ADH) activity was significantly decreased at 30 DAP, but unaffected at 42 DAP in QG fruits. There was no difference for alcohol acetyltransferase (AAT) activity between QG and SG fruits. The expression level of CmADH2 was significantly higher at 30 DAP and 42 DAP, but CmAAT2 was significantly lower at 42 DAP in QG fruits compared with SG fruits. In RG fruits, the main aroma compounds including butanoic acid ethyl ester, 2-methyl-2-butene-1-al, and 2-methylheptan-1-al were absent, while the volatile compounds with unpleasant odor characteristics including trans, cis-2,6-nonadien-1-ol, (E,E)-2,4-heptadienal, octanoic acid, and styrene were detected. Compared with SG fruits, 1-nonanol and 1-heptanol with green odor characteristics were significantly increased, but eucalyptol and farnesene with fruity aroma characteristics were significantly decreased in RG fruits. The ADH activity of RG fruits was significantly lower than that of SG fruits at 30 DAP and the AAT activity was significantly lower than that of SG fruits at 42 DAP. In addition, the expression levels of CmADH and CmAAT homologs in RG fruits were significantly lower than those in SG or QG fruits. These results show that grafting with pumpkin rootstocks affected the main aroma components, reduced ADH and AAT activities, and down-regulated the expression levels of CmADHs and CmAATs in the melon fruits. This study reveals the mechanism of different rootstocks on melon fruit aroma quality, and lays a theoretical foundation for the selection of rootstocks in melon production. Future studies using overexpression or CRISPR/CAS system to obtain stable transgenic lines of genes encoding key aromatic volatiles, would be promising to effectively improve the flavor quality of melon.

Volatomics-assisted characterization of aroma and off-flavor contributors in fresh and thermally treated kiwifruit juice

The distinctive aroma profile of kiwifruit juice was significantly changed during thermal treatment, however, the theoretical basis for clarifying and controlling the changes was deficient. In this study, we applied volatomics techniques to investigate the contributors of off-flavors in thermally treated kiwifruit juice. Sixteen aroma compounds were identified to be responsible for the typical "fruity", "grassy", and "cucumber-like" flavors of fresh kiwifruit by two different fused silica capillary columns coupled with chromatography-olfactometry/detection frequency (GC-O/DF) analysis and calculation of odor activity value (OAV). Thirty-one odor-active compounds were determined as important contributors to the sensory profile of thermally treated kiwifruit juice, 14 of which were common to all varieties investigated. The key aroma compounds on fresh kiwifruit significantly decreased after thermal treatment, while decanal, (E)-2-decenal, methional, β-damascenone, 1-octen-3-one, DMHF, and dimethyl sulfide which presented undesirable cooked cabbage/potato, roasted fruit, and sulfurous odors, were accumulated in a large amount. By applying PLSR analysis, (E)-2-decenal, methional, β-damascenone, DMHF, and dimethyl sulfide were further verified to have great contributions to the formation of the cooked off-flavor during thermal treatment. Moreover, XX was found to be more thermal-sensitive and more prone to forming cooked off-flavors after thermal treatment. This study could provide theoretical guidance for the regulation of thermal-induced off-flavors during the manufacturing of kiwifruit juice.

Review on Sensor Array-Based Analytical Technologies for Quality Control of Food and Beverages

Food quality control is an important area to address, as it directly impacts the health of the whole population. To evaluate the food authenticity and quality, the organoleptic feature of the food aroma is very important, such that the composition of volatile organic compounds (VOC) is unique in each aroma, providing a basis to predict the food quality. Different types of analytical approaches have been used to assess the VOC biomarkers and other parameters in the food. The conventional approaches are based on targeted analyses using chromatography and spectroscopies coupled with chemometrics, which are highly sensitive, selective, and accurate to predict food authenticity, ageing, and geographical origin. However, these methods require passive sampling, are expensive, time-consuming, and lack real-time measurements. Alternately, gas sensor-based devices, such as the electronic nose (e-nose), bring a potential solution for the existing limitations of conventional methods, offering a real-time and cheaper point-of-care analysis of food quality assessment. Currently, research advancement in this field involves mainly metal oxide semiconductor-based chemiresistive gas sensors, which are highly sensitive, partially selective, have a short response time, and utilize diverse pattern recognition methods for the classification and identification of biomarkers. Further research interests are emerging in the use of organic nanomaterials in e-noses, which are cheaper and operable at room temperature.

Targeted multi-platform metabolome analysis and enzyme activity analysis of kiwifruit during postharvest ripening

Kiwifruit is a climacteric fruit, in which the accumulation of flavor substances mainly occurs at the postharvest ripening stage. However, the dynamic changes in metabolite composition remain poorly understood. Here, targeted multi-platform metabolome analysis based on GC-MS and UPLC-MS/MS and enzyme activity analysis were performed at different postharvest ripening stages of kiwifruit. A total of 12 soluble sugars and 31 organic acids were identified. The main soluble sugars are sucrose, glucose and fructose, which exhibited similar variation tendencies along with the extension of ripening. The main organic acids are citric acid, quinic acid and malic acid, which showed different variation patterns. A total of 48 energy metabolites were identified, which were classified into two groups based on the content variation. The content of substances related to the respiratory metabolic pathway decreased gradually along with postharvest ripening, and there was obvious accumulation of downstream products such as amino acids at the late ripening stage. A total of 35 endogenous hormones were identified, among which seven cytokinins were highly accumulated at the later stage of softening. We further investigated the dynamic changes in the activities of 28 ripening-related enzymes. As a result, the activities of 13 enzymes were highly correlated with changes in starch, total pectin, and soluble sugars, and those of seven enzymes were closely associated with the change in firmness. In conclusion, this study comprehensively describes the dynamic changes in soluble sugars, organic acids, hormones, energy substances, and ripening-related enzyme activities during kiwifruit postharvest ripening, and provides a theoretical basis for the postharvest quality improvement of kiwifruit.

Comparative Analysis of the Quality in Ripe Fruits of Cuiguan Pear from Different Regions

The Cuiguan pear is called "June snow" and the skin is thin; the meat is crisp and juicy; the taste is thick and fresh; and the juice is rich and sweet. In this study, the volatile organic compounds and the sensory and physicochemical parameters of the Cuiguan pear from four different regions of China (Sichuan (SC), Shangdong (SD), Chongming (CM), Zhuanghang (ZH)) were assessed. The highest differences in the physicochemical parameters were observed between four regions. The volatile fingerprints of GC-IMS showed great differences in the volatile of the Cuiguan pear, which suggested that the aroma of pears could be largely impacted by origin areas. (E)-ethyl-2-hexenoate can be used to distinguish between the 'CM' and pears from other regions. High contents of 2-heptanone, 1-pentanol, 1-butanol, 3-methylbutanol, butyl 2-methylbutanoate, heptyl acetate and butyl acetate were observed in the 'SD'. Dimethyl trisulfide, 6-methyl-5-hepten-2-one, 3-hydroxy-2-butanone, 1-penten-3-one, beta-pinene, γ-terpinene, propanal, (e)-2-pentenal, (e)-2-heptenal, 1-pentanol and 3-methyl-1-pentanol were primarily contained in the 'ZH'. Principal component analysis showed that there was very good discrimination based on the information obtained from GC-IMS for four samples. These findings were in agreement with the sensory analysis. In the opinion of the respondents to the consumer test, 'ZH' resulted in the most appreciated sample based on the average scores of the acceptability. This study provides some reference for the development and utilization of the Cuiguan pear.

Comparative Study on Physicochemical and Nutritional Qualities of Kiwifruit Varieties

In order to study the physicochemical and nutritional characteristics of kiwifruit varieties, 14 kiwifruits from different species with different flesh colors were selected for research. The pectin content was significantly higher in green-fleshed kiwifruits than those in red-fleshed and yellow-fleshed kiwifruits. Red-fleshed kiwifruits had the highest total flavonoid content, and green-fleshed kiwifruits in A. eriantha had the highest chlorophyll a content, chlorophyll b content and total carotenoid content. The energy and carbohydrate contents of yellow-fleshed kiwifruits were significantly lower than those of red-fleshed kiwifruit. Moreover, the protein contents in A. chinensis and A. chinensis var. deliciosa were higher than those in other species. The content of vitamin C in A. eriantha was far higher than in other kiwifruits. Red-fleshed kiwifruits had a significantly higher vitamin E and vitamin B1 content than green-fleshed kiwifruits. In addition, 1-pentanol, trans-2-hexen-1-ol, n-hexane and styrene presented only in red-fleshed kiwifruits. Therefore, these could be used as a characteristic fragrance for red-fleshed kiwifruits. Moreover, the varieties were ranked comprehensively by principal component analysis (PCA), among which the top four highest-ranking kiwifruits among the 14 varieties were 'Huate', 'MHYX', 'Jinkui' and 'Xuxiang', respectively. This study provides a reference for consumers and markets on quality improvement and processing.

Effects of green manure planting mode on the quality of Korla fragrant pears (Pyrus sinkiangensis Yu)

In this study, a three-year experiment on the fragrant pear orchard was conducted to investigate the effects of different varieties of green manure on the Korla fragrant pear fruit quality, with a view to finding a suitable green manure planting mode for Korla fragrant pear orchard. Green manures were planted in spaces among rows of pear trees, and then smashed and pressed into the soil as fertilisers by the agricultural machinery equipment in their full bloom period. In the experiment, four planting modes of green manure had been set for comparison: SA: Leguminosae green manures alfalfa (Medicago sativa L.), SP: Poaceae green manures oats (Avena sativa L.), ST: Cruciferae green manures oilseed rape (Brassica napus L.), and S: orchard authigenic green manures (Chenopodium album L., Mulgedium tataricum (L) DC., and Phragmites australis (Cav.) Trin. ex Steud.). Apart from that, eleven fruit quality indicators were analyzed to evaluating the effects of different green manure planting mode on the quality of fragrant pear. According to analysis of variance (ANOVA) results, there were significant differences among four planting modes in terms of nine fruit quality indicators (P<0.05). In addition, the correlation analysis (CA) results revealed that there were different degrees of correlations among quality indicators. On this basis, repeated information among indicators was eliminated by principal component analysis (PCA), thus simplifying and recombining the three principal components. All in all, these three principal components reflect appearance traits, internal nutritive value and taste of fruits, respectively. Specifically, SA significantly improved the internal quality and nutritive value of fruits, SP improved the physical traits of fruits, and ST significantly improved the taste of fruits. Based on the PCA results, a comprehensive evaluation model of fruit quality was constructed. The are comprehensive fruit quality scores:SA>SP>ST>S.

New Mater-Bi, Biodegradable Mulching Film for Strawberry (Fragaria × Ananassa Duch.): Effects on Film Duration, Crop Yields, Qualitative, and Nutraceutical Traits of Fruits

In the main strawberry areas of Southern Italy, cultivation is carried out by transplanting plants on raised beds (30–40 cm from ground level), mulched with black polyethylene (PE). This technique has becoming increasingly expensive due to the growing prices of plastic mulches, the cost to remove them at the end of crop cycle, and the difficulty to dispose of black, dirty plastic films. The main objective of this research was the replacement of PE mulch with a new biodegradable mulching film Mater-Bi^®-based (Novamont), characterized by an increased permanence in the field designed for long crop life. In 2021, two Mater-Bi-based, black, 18 μm thick mulching films were tested under tunnel: N5 as innovative film and N18 as commercial standard film. Black PE film, 50 μm thick was the control. Strawberry cultivars ‘Sabrina’ and ‘Elide’ were cropped on the three mulching films according to a split plot design with four replications. Harvests lasted from March to June 2021. Cvs Sabrina and Elide yielded around 40 t ha⁻¹, while the mean effect of mulching films did not point out differences between the biodegradable mulches and PE. In 4 out of 12 harvests we analyzed samples of fruits to assess the influence of mulches on the contents of °Brix, polyphenols, antioxidant activity, ascorbic acid, flavonoids, and anthocyanins. On average, °Brix was clearly improved in fruits on PE compared to biodegradable films, while all the other qualitative traits resulted in being more dependent on the cultivars and times of sampling effects. Overall, biodegradable mulches are a viable alternative to PE mulch, and the innovative N5 film appeared promising for the enhancement of durability of soil coverage in a long-lasting cycle.

Branched-Chain Volatiles in Fruit: A Molecular Perspective

Branched-chain volatiles (BCVs) constitute an important family of fruit volatile metabolites essential to the characteristic flavor and aroma profiles of many edible fruits. Yet in contrast to other groups of volatile organic compounds important to fruit flavor such as terpenoids, phenylpropanoids, and oxylipins, the molecular biology underlying BCV biosynthesis remains poorly understood. This lack of knowledge is a barrier to efforts aimed at obtaining a more comprehensive understanding of fruit flavor and aroma and the biology underlying these complex phenomena. In this review, we discuss the current state of knowledge regarding fruit BCV biosynthesis from the perspective of molecular biology. We survey the diversity of BCV compounds identified in edible fruits as well as explore various hypotheses concerning their biosynthesis. Insights from branched-chain precursor compound metabolism obtained from non-plant organisms and how they may apply to fruit BCV production are also considered, along with potential avenues for future research that might clarify unresolved questions regarding BCV metabolism in fruits.

Phytochemical Analysis and Biological Activity of Three Stachys Species (Lamiaceae) from Romania

Three species of Stachys genus (S. byzantina, S. officinalis, S. sylvatica) were investigated in the present study in terms of aromatic profile and total polyphenol content, as well as antibacterial activity and antioxidant capacity. Gas chromatography coupled with flame ionization detection (GC/FID) was used for exploration of the herbal alcoholic extracts. Using statistical analysis, volatile organic compounds (VOCs) and total phenolic chemical fingerprints were compared in order to describe differences and identify putative signature traits of the three Stachys species. The results showed that the analyzed Stachys extracts have a total polyphenol content being between 197 ± 0.27 mg GAE/g for S. sylvatica and 232 ± 43 mg GAE/g for S. officinalis. The antioxidant activity was between 444 ± 58 mM Trolox/g (S. sylvatica) and 602 ± 75 mM Trolox/g (S. officinalis). The volatile compounds identified were mostly sesquiterpenes, followed by monoterpenes and secondary compounds. The most abundant in all three species was germacrene D (21.9% 28–25.2%). The multivariate analysis demonstrated the potential of using plant tissue VOC profiles to discriminate between different Stachy species, with a total of 31 VOCs being identified from all three species. Although there were strong similarities among the three species’ VOC profiles, distinctions can be made using chemometric analysis. The microbiological results showed an antimicrobial capacity of all three extracts, especially on Gram-positive bacteria. In addition to increasing consumers’ understanding regarding the health benefits of these Stachy species, this investigation contributes to defining and preserving a precious genetic and cultural-historical biodiversity.

Development and characterization of aldehyde-sensitive cellulose/chitosan/beeswax colorimetric papers for monitoring kiwifruit maturity

In this study, we developed an in-package colorimetric paper to monitor the ripeness of kiwifruit by detecting the release of aldehydes. Strongly hydrophobic composite films were prepared using chitosan as the matrix and beeswax as an additive. A piece of cellulose paper containing methyl red and bromocresol violet as color indicators was heat-sealed between two hydrophobic films to protect the indicators from the effects of fruit respiration and transpiration. The nucleophilic addition reaction between aldehydes and OH^- (Cannizzaro reaction) changes the pH in the paper and triggers a color change in the indicators. As the kiwifruit ripens, the colorimetric paper changes from bluish-purple to dark red and then gradually to red. A mobile phone application was further used to measure the RGB values and link them to kiwifruit ripeness. This intelligent paper can be used for the accurate and convenient monitoring of produce in real time.

Analysis of the Aroma Chemical Composition of Commonly Planted Kiwifruit Cultivars in China

The aroma chemical composition of commonly planted kiwifruit cultivars in China was analyzed. The combination of 2-octanone with 3-octanone was the most suitable dual internal standard for quantitative analysis in GC-MS. A total of 172 aroma components in 23 kiwifruit cultivars were detected, and ethyl butanoate, (E)-2-hexen-1-ol, and (E)-2-hexenal could be considered the core aroma components in kiwifruit, but still need further confirmation using Sensomics. E-nose could effectively distinguish different cultivars of kiwifruit. Clustering based on GC-MS and E-nose results tends to be consistent and demonstrate a certain degree of similarity. Kiwifruit cultivars with different flesh colors cannot be effectively distinguished by their aroma chemical compositions. Different species of kiwifruit can be distinguished to some extent by their aroma chemical compositions, but the effect was not satisfactory. These results could prove valuable in the breeding, planting, and marketing of kiwifruits.

Comparative analysis of volatile and carotenoid metabolites and mineral elements in the flesh of 17 kiwifruit

Kiwifruit contains abundant nutritive compounds and is highly favored by the consumers worldwide. Therefore, detailed metabolic profiling is important to provide theoretic basis for the improvement of kiwifruit quality. In this study, the levels of volatiles, carotenoids, and mineral elements in the flesh of 17 kiwifruit accessions were evaluated. Acids and esters were the main volatiles in kiwifruit. During these 17 kiwifruit accessions, "Chenhong," three "Jinyan," and two "Guichang" germplasms were specifically rich in aromatic esters, which might be associated with their special taste. The main carotenoids were lutein, β-carotene, and zeaxanthin, and their levels were also genotype specific, with the green-fleshed "Guichang" having the highest level of carotenoids, and red-fleshed "Fuhong" and "Chenhong" being rich in zeaxanthin. Partial correlation analysis showed that the contents of some mineral elements were significantly correlated with those of specific volatiles and carotenoids, indicating the impacts of mineral elements on the accumulation of volatiles and carotenoids in the kiwifruit flesh. These results indicated that the contents of carotenoids and volatiles seemed to be affected by mineral elements and also provided a new potential method for improving fruit flavor quality in production.

Aroma characteristics of cloudy kiwifruit juices treated with high hydrostatic pressure and representative thermal processes

The commercial kiwifruit juice is deficient in a theoretical basis for the control of aroma characteristics during sterilization. To investigate the different sterilization methods on the aroma of kiwifruit juice, three sterilized kiwifruit juice samples, including pasteurization (PS), high temperature short time (HTST) and high hydrostatic pressure (HHP) sterilization, were observed. Results showed that a total of 15 major aroma-active compounds were identified in fresh kiwifruit juice by combination of detection frequency (DF) analysis and odor activity value (OAV); while the changes of these aroma-active compounds during PS, HTST and HHP sterilization were further studied. Quantitative descriptive analysis (QDA) was applied to validate the sensory differences, showing fruity and grassy notes changed a lot after sterilization, and the HHP sample was similar to fresh sample (FS) in comparison of samples treated by other sterilization methods. Further partial least squares regression analysis (PLSR) coincided with the overall note. Among these aroma-active compounds, the decrease of C6 aldehydes and C6 alcohols such as hexanal, (E)-2-hexenal and 1-hexanol might result in the great change of grassy note while the change of fruity note might be well correlated with the decrease of esters such as methyl butyrate and ethyl butyrate during processing.

Kiwifruit (Actinidia spp.): A review of chemical diversity and biological activities

Kiwifruit (Actinidia spp.) is a commercially important fruit crop. Various species and cultivars, non-fruit plant parts, and agricultural and processing wastes are underutilized. A broad-scoped review of kiwifruit guides further innovative applications. Different kiwifruit varieties and edible and nonedible parts varied in the composition of dietary nutrients including polyphenols, vitamins, dietary fiber, and functional ingredients, such as starch and protease and bioactive phytochemicals. Kiwifruits exhibit antioxidative, antiproliferative, antiinflammatory, antimicrobial, antihypertensive, antihypercholesterolemic, neuroprotective, antiobese properties and promote gut health. Clinically significant effects of kiwifruit on prevention and/or treatment of major chronic diseases are not yet evident. Varieties and plant parts, extraction, analytical and processing methods affect the physicochemical and biological properties of kiwifruit-derived ingredients. Allergens, mycotoxins, pesticides and heavy metals are the chemical hazards of kiwifruits. Future research should be focused on sustainable uses of underutilized resources as functional ingredients, bioactive compound purification, composition-activity relationships, and physiological mechanisms and clinical significance of kiwifruits.

Comparative Analysis of Physicochemical Characteristics, Nutritional and Functional Components and Antioxidant Capacity of Fifteen Kiwifruit (Actinidia) Cultivars-Comparative Analysis of Fifteen Kiwifruit (Actinidia) Cultivars

Physicochemical characteristics, nutritional and functional components, and the antioxidant capacity of 15 kinds of domestic and imported kiwifruit in China were studied. Kiwifruit was classified according to flesh color or species, and the differences were analyzed and compared. Results demonstrated Ruiyu had the highest sugar-acid ratio, and Hongshi No.2 was an excellent cultivar with strong antioxidant capacity. TPC (total polyphenol content) and AAC (ascorbic acid content) showed a significant positive correlation. TPC was the greatest antioxidant contributor in the DPPH and FRAP assays. The sugar-acid ratio and TFC (total flavonoids content) in red-fleshed kiwifruit were significantly higher than those in yellow-fleshed and green-fleshed ones. The composition of free amino acids had a tendency to distinguish A. deliciosa and A. chinensis, but this needs further verification. In addition, the contents of mineral elements, folic acid and L-5-methyltetrahydrofolate were also analyzed. Generally, kiwifruit contains comprehensive nutrients and has strong antioxidant capacity. Cultivar is one of the main factors affecting nutritional and functional properties and antioxidant capacity.

Design of Healthy Snack Based on Kiwifruit

Kiwifruit is an excellent source of vitamin C and other bioactive compounds, which contribute to its high antioxidant activity. However, the fruits with small size and low weight are considered waste and are unprofitable; therefore, the production of healthy kiwifruit-based dried snacks, which contain a lot of health-beneficial ingredients, could be a viable alternative for their use. The aim of this study was to develop formulations and methods to produce attractive and nutritionally valuable dried snacks based on yellow kiwifruit. Three different puree formulations (kiwifruit; fennel; and strawberry, lemon, or spinach) with or without addition of sugar were subjected to two drying methods: freeze-drying (fruit bars) and conventional hot air drying (fruit leathers). The obtained products were analysed for their content of total polyphenols (TPs), flavonoids, and vitamin C, as well as their antioxidant activity. The results showed that snacks prepared by freeze-drying (fruit bars) presented higher TP, vitamin C, and flavonoids content than those prepared by convective drying; however, the antioxidant activity did not always follow this trend. The amount of bioactive compounds depended on the formulation used for the preparation of snacks. The effect of the sugar addition seems to be strictly related to the mix used and specific bioactive compound investigated.

Effect of Three Different Aloe vera Gel-Based Edible Coatings on the Quality of Fresh-Cut "Hayward" Kiwifruits

In recent years, the market for minimally processed fruit has increased. Fresh-cut fruits are characterized by a short shelf life due to the processing phases that accelerate the ripening courses. The aim of this work is to analyze the effect on the quality of fresh-cut Hayward kiwis of three different edible coatings based on (1) Aloe vera gel, (2) Aloe vera gel + hydroxypropyl methylcellulose and (3) Aloe vera gel + lemon essential oil. Fruit firmness, weight loss, color, soluble solids content, titratable acidity, microbial load and sensory analysis were evaluated as fresh after 2, 4, 7 and 10 days. Aloe vera gel and Aloe vera gel + lemon essential oil maintained the best values, as they acted as a barrier to gas exchange and further reduced the microbial load. These results were confirmed by sensory analysis: Aloe vera gel + hydroxypropyl methylcellulose does not alter the natural taste of kiwi slices, Aloe vera gel + lemon essential oil gives the characteristic taste of lemon essential oil and Aloe vera gel gives an herbaceous taste. The Aloe vera gel, in combination with these additives, maintains the ability to preserve the quality of fresh-cut kiwifruit.