Physiological disorders in cold-stored 'Autumn Sense' hardy kiwifruit depend on the storage temperature and the modulation of targeted metabolites

This study aimed to elucidate the effects of storage temperature on various fruit quality attributes, physiological disorders, and associated metabolites in the 0.5, 3, or 10 °C stored hardy kiwifruit. Peel pitting, which was highest in the 0.5 °C stored fruit, was identified as a chilling injury symptom of hardy kiwifruit. Proline and branched-chain amino acid contents showed higher values at 0.5 °C stored fruit as chilling responses. On the other hand, fruit shriveling and decay were highest in the 10 °C after 5 weeks of storage. The 10 °C storage induced fruit ripening during 3 weeks, but fruit shriveling and decay were severe after 5 weeks of storage. Therefore, storing the 'Autumn Sense' hardy kiwifruit at proper temperatures would be more beneficial, as it alters targeted metabolites and helps reduce the incidence of physiological disorders during cold storage.

The genus Actinidia Lindl. (Actinidiaceae): A comprehensive review on its ethnobotany, phytochemistry, and pharmacological properties

ETHNOPHARMACOLOGICAL RELEVANCE

Actinidia Lindl. belongs to the family Actinidiaceae. Plants of this genus are popularly known as kiwifruits and are traditionally used to treat a wide range of ailments associated with digestive disorders, rheumatism, kidney problems, cardiovascular system, cancers, dyspepsia, hemorrhoids, and diabetes among others.

AIM

This review discusses the ethnobotanical uses, phytochemical profile, and known pharmacological properties of Actinidia plants, to understand their connotations and provide the scientific basis for future studies.

MATERIALS AND METHODS

The data were obtained by surveying journal articles, books, and dissertations using various search engines such as Google Scholar, PubMed, Science Direct, Springer Link, and Web of Science. The online databases; World Flora Online, Plants of the World Online, International Plant Names Index, and Global Biodiversity Information Facility were used to confirm the distribution and validate scientific names of Actinidia plants. The isolated metabolites from these species were illustrated using ChemBio Draw ultra-version 14.0 software.

RESULTS

Ten (10) species of Actinidia genus have been reported as significant sources of traditional medicines utilized to remedy diverse illnesses. Our findings revealed that a total of 873 secondary metabolites belonging to different classes such as terpenoids, phenolic compounds, alcohols, ketones, organic acids, esters, hydrocarbons, and steroids have been isolated from different species of Actinidia. These compounds were mainly related to the exhibited antioxidant, antimicrobial, anti-inflammatory, antidiabetic, antiproliferative, anti-angiogenic, anticinoceptive, anti-tumor, and anticancer activities.

CONCLUSION

This study assessed the information related to the ethnobotanical uses, phytochemical compounds, and pharmacological properties of Actinidia species, which indicate that they possess diverse bioactive metabolites with interesting bioactivities. Actinidia plants have great potential for applications in folklore medicines and pharmaceuticals due to their wide ethnomedicinal uses and biological activities. Traditional uses of several Actinidia species are supported by scientific evidences, qualifying them as possible modern remedies for various ailments. Nonetheless, the currently available data has several gaps in understanding the herbal utilization of most Actinidia species. Thus, further research into their toxicity, mechanisms of actions of the isolated bioactive metabolites, as well as scientific connotations between the traditional medicinal uses and pharmacological properties is required to unravel their efficacy in therapeutic potential for safe clinical application.

Antioxidant Activity Analysis of Native Actinidia arguta Cultivars

Kiwiberry (Actinidia arguta) is a perennial fruit tree belonging to the family Actinidiaceae. Kiwiberries are known to have an extremely high concentration of sugars, phenolics, flavonoids, and vitamin C, and possess delicious taste and health-promoting properties. Numerous studies have focused on kiwiberry fruits, demonstrating that they possess a higher phytochemical content and greater antioxidant activities than other berry fruits. The purpose of this study was to compare the phytochemical content and antioxidant potential of leaf, stem, root, and fruit extracts from twelve kiwiberry cultivars grown in Wonju, Korea, characterized by a Dwa climate (Köppen climate classification). In most kiwiberry cultivars, the total phenolic (TPC) and total flavonoid (TFC) phytochemical content was significantly higher in leaf and stem tissues, while the roots exhibited higher antioxidant activity. In fruit tissues, the TPC and TFC were higher in unripe and ripe kiwiberry fruits, respectively, and antioxidant activity was generally higher in unripe than ripe fruit across most of the cultivars. Based on our results, among the 12 kiwiberry cultivars, cv. Daebo and cv. Saehan have a significantly higher phytochemical content and antioxidant activity in all of the tissue types, thus having potential as a functional food and natural antioxidant.

Bioactive compounds from Actinidia arguta fruit as a new strategy to fight glioblastoma

In recent years, there has been a significant demand for natural products as a mean of disease prevention or as an alternative to conventional medications. The driving force for this change is the growing recognition of the abundant presence of valuable bioactive compounds in natural products. On recent years Actinia arguta fruit, also known as kiwiberry, has attracted a lot of attention from scientific community due to its richness in bioactive compounds, including phenolic compounds, organic acids, vitamins, carotenoids and fiber. These bioactive compounds contribute to the fruit's diverse outstanding biological activities such as antioxidant, anti-inflammatory, neuroprotective, immunomodulatory, and anti-cancer properties. Due to these properties, the fruit may have the potential to be used in the treatment/prevention of various types of cancer, including glioblastoma. Glioblastoma is the most aggressive form of brain cancer, displaying 90 % of recurrence rate within a span of 2 years. Despite the employment of an aggressive approach, the prognosis remains unfavorable, emphasizing the urgent requirement for the development of new effective treatments. The preclinical evidence suggests that kiwiberry has potential impact on glioblastoma by reducing the cancer self-renewal, modulating the signaling pathways involved in the regulation of the cell phenotype and metabolism, and influencing the consolidation of the tumor microenvironment. Even though, challenges such as the imprecise composition and concentration of bioactive compounds, and its low bioavailability after oral administration may be drawbacks to the development of kiwiberry-based treatments, being urgent to ensure the safety and efficacy of kiwiberry for the prevention and treatment of glioblastoma. This review aims to highlight the potential impact of A. arguta bioactive compounds on glioblastoma, providing novel insights into their applicability as complementary or alternative therapies.

Main flavor compounds and molecular regulation mechanisms in fruits and vegetables

Fruits and vegetables (F&V) are an indispensable part of a healthy diet. The volatile and nonvolatile compounds present in F&V constitute unique flavor substances. This paper reviews the main flavor substances present in F&V, as well as the biosynthetic pathways and molecular regulation mechanisms of these compounds. A series of compounds introduced include aromatic substances, soluble sugars and organic acids, which constitute the key flavor substances of F&V. Esters, phenols, alcohols, amino acids and terpenes are the main volatile aromatic substances, and nonvolatile substances are represented by amino acids, fatty acids and carbohydrates; The combination of these ingredients is the cause of the sour, sweet, bitter, astringent and spicy taste of these foods. This provides a theoretical basis for the study of the interaction between volatile and nonvolatile substances in F&V, and also provides a research direction for the healthy development of food in the future.

The Pollen Donor Affects Seed Development, Taste, and Flavor Quality in 'Hayward' Kiwifruit

To investigate how different species or ploidy level of pollen donors affects the fruit quality of kiwifruit, flowers of 'Hayward' kiwifruit (a hexaploid Actinidia deliciosa cultivar, 6x) were hand-pollinated with pollen from ten different male donors. Kiwifruit plants pollinated with four distant species-M7 (2x, A. kolomikta), M8 (4x, A. arguta), M9 (4x, A. melanandra), and M10 (2x, A. eriantha)-had a low fruit-setting rate and therefore were not investigated further. Of the other six treatments, kiwifruit plants pollinated with M4 (4x, A. chinensis), M5 (6x, A. deliciosa) M6 (6x, A. deliciosa) had a larger fruit size and weight than those pollinated with M1 (2x, A. chinensis) and M2 (2x, A. chinensis). However, pollination with M1 (2x) and M2 (2x) resulted in seedless fruits, having few small and aborted seeds. Notably, these seedless fruits had higher fructose, glucose, and total sugar and lower citric acid content. This resulted in a higher sugar to acid ratio compared to fruits from plants pollinated with M3 (4x, A. chinensis), M4 (4x), M5 (6x), and M6 (6x). Most volatile compounds increased in the M1 (2x)- and M2 (2x)-pollinated fruit. A combination of principal component analysis (PCA), electronic tongue, and electronic nose suggested that the different pollen donors significantly affected the kiwifruit's overall taste and volatiles. Specifically, two diploid donors had the most positive contribution. This was in agreement with the findings from the sensory evaluation. In conclusion, the present study showed that the pollen donor affected the seed development, taste, and flavor quality of 'Hayward' kiwifruit. This provides useful information for improving the fruit quality and breeding of seedless kiwifruit.

Fruit-Carrot-Based Smoothies as Innovative Products with a Complex Matrix of Bioactive Compounds Effected on Activities of Selected Digestive Enzymes and Cholinesterases In Vitro

In this study, four different carrot varieties (purple, yellow, white, and orange) were used in the production of smoothies with raspberry, apple, pear, strawberry, and sour cherry juices. The in vitro inhibition effects against α- amylase, α- glucosidase, pancreatic lipase, acetylcholinesterase, and butyrylcholinesterase were measured, bioactive compounds, physicochemical characteristics, including sensorial features were described. The antioxidant activities of the studied samples were analyzed using the ORAC, ABTS, and FRAP methods. The raspberry-purple carrot smoothie showed the highest antioxidant activity against lipase and butyrylcholinesterase enzyme activity. The sour cherry-purple carrot smoothie showed the highest total soluble solids, total phenolic acid, total anthocyanins, and procyanidin contents; dry mass; and osmolality. Although the apple-white carrot smoothie achieved the highest acceptance after sensorial evaluation, it did not exhibit any potent biological activities. Thus, food products with purple carrot, raspberry, and sour cherry ingredients are suggested as functional and/or novel matrix compositions with high antioxidant potential.

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.

Possibility to use the different sizes and colors of carrots for the production of juices - comparison of bioactive compounds, nutritional quality, pro-health properties, and sensory evaluation

BACKGROUND

Carrot is a popular vegetable consumed by people of all age groups and is used in various food products because of its high nutritional content, especially vitamin A.

RESULTS

In the present study, colorful fresh carrot juices of 12 carrot varieties were investigated for in vitro antidiabetic, anti-aging, and anti-obesity activities with antioxidant potential by ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and FRAP (ferric reducing ability of plasma) assays. The studied juices were also compared for physicochemical characteristics: titratable acidity, pH, pectin content, total soluble solids, dry mass, ash, viscosity, turbidity, osmolality, and color. The results of the study showed that normal purple carrot juice exhibited the best activities in all biological and antioxidant tests, except for anti-α-glucosidase activity. Normal purple carrot juice also had the highest total mineral content with elevated results for titratable acidity, pH, total soluble solids, dry mass, ash, viscosity, and osmolality.

CONCLUSION

Purple carrot juices demonstrated elevated health-promoting activities and could be used in blended beverage recipes to attract children's attention. The results of sensorial characteristics (appearance, color, and taste) of juices, however, showed that people are more familiar with orange carrot products. © 2022 Society of Chemical Industry.

Comprehensive Analysis of Metabolome and Transcriptome in Fruits and Roots of Kiwifruit

Kiwifruit (Actinidia chinensis) roots instead of fruits are widely used as Chinese medicine, but the functional metabolites remain unclear. In this study, we conducted comparative metabolome analysis between root and fruit in kiwifruit. A total of 410 metabolites were identified in the fruit and root tissues, and of them, 135 metabolites were annotated according to the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway. Moreover, 54 differentially expressed metabolites (DEMs) were shared in root and fruit, with 17 DEMs involved in the flavonoid pathway. Of the 17 DEMs, three flavonols (kaempferol-3-rhamnoside, L-Epicatechin and trifolin) and one dihydrochalcone (phloretin) showed the highest differences in the content level, suggesting that flavonols and dihydrochalcones may act as functional components in kiwifruit root. Transcriptome analysis revealed that genes related to flavonols and dihydrochalcones were highly expressed in root. Moreover, two AP2 transcription factors (TFs), AcRAP2-4 and AcAP2-4, were highly expressed in root, while one bHLH TF AcbHLH62 showed extremely low expression in root. The expression profiles of these TFs were similar to those of the genes related to flavonols and dihydrochalcones, suggesting they are key candidate genes controlling the flavonoid accumulation in kiwifruit. Our results provided an insight into the functional metabolites and their regulatory mechanism in kiwifruit root.

Comparative changes of health-promoting phytochemicals and sugar metabolism of two hardy kiwifruit (Actinidia arguta) cultivars during fruit development and maturity

Introduction

Hardy kiwifruit (Actinidia arguta) has an extensive range of nutritional and bioactive compounds and has been valued as a great resource for kiwifruit breeding. A better understanding of the dynamic changes of the composition and accumulation of nutritional compounds during fruit development and ripening is required before genetic or cultural improvements can be targeted.

Methods

In the present study, the phytochemical analysis of two A. arguta cultivars 'Yilv' and 'Lvmi-1' showed that they comprised different morphology, with a higher fruit diameter while a lower vertical fruit diameter of 'Lvmi-1' compared with 'Yilv'. The antioxidant capacity of both cultivars decreased during the maturity time and showed no significant difference between them. Furthermore, although glucose gradually increased during the maturity time, the predominant sugar composition was speculated to be fructose in 'Lvmi-1' fruit while sucrose in 'Yilv' fruit at the early fruit developmental stages. Moreover, the predominant acids in 'Yilv' and 'Lvmi-1' were citric acid followed by quinic acid, malic acid, and oxalic acid. The expression of sugar- and starch-related genes encoding the crucial enzymes suggested different changes in 'Yilv' and 'Lvmi-1'. Notably, a subsequent correlation analysis showed a significant positive correlation between sucrose phosphate synthase (SPS) expression and glucose in 'Yilv', fructokinase (FK) expression, and starch content in 'Lvmi-1', implying their vital roles in sugar and starch accumulation. By contrast, a significant negative correlation between FK expression and fructose in 'Lvmi-1' fruit was observed.

Results and Discussion

In summary, our results provide supplementary information for the dynamic changes of nutritional compounds and antioxidant capacity during hardy kiwifruit maturity time and give a clue for exploring the mechanism of sugar and starch accumulation in hardy kiwifruit.

Recent Progress in the Study of Taste Characteristics and the Nutrition and Health Properties of Organic Acids in Foods

Organic acids could improve the food flavor, maintain the nutritional value, and extend the shelf life of food. This review summarizes the detection methods and concentrations of organic acids in different foods, as well as their taste characteristics and nutritional properties. The composition of organic acids varies in different food. Fruits and vegetables often contain citric acid, creatine is a unique organic acid found in meat, fermented foods have a high content of acetic acid, and seasonings have a wide range of organic acids. Determination of the organic acid contents among different food matrices allows us to monitor the sensory properties, origin identification, and quality control of foods, and further provides a basis for food formulation design. The taste characteristics and the acid taste perception mechanisms of organic acids have made some progress, and binary taste interaction is the key method to decode multiple taste perception. Real food and solution models elucidated that the organic acid has an asymmetric interaction effect on the other four basic taste attributes. In addition, in terms of nutrition and health, organic acids can provide energy and metabolism regulation to protect the human immune and myocardial systems. Moreover, it also exhibited bacterial inhibition by disrupting the internal balance of bacteria and inhibiting enzyme activity. It is of great significance to clarify the synergistic dose-effect relationship between organic acids and other taste sensations and further promote the application of organic acids in food salt reduction.

Nutritional Component Analyses in Different Varieties of Actinidia eriantha Kiwifruit by Transcriptomic and Metabolomic Approaches

Actinidia eriantha is a unique germplasm resource for kiwifruit breeding. Genetic diversity and nutrient content need to be evaluated prior to breeding. In this study, we looked at the metabolites of three elite A. eriantha varieties (MM-11, MM-13 and MM-16) selected from natural individuals by using a UPLC-MS/MS-based metabolomics approach and transcriptome, with a total of 417 metabolites identified. The biosynthesis and metabolism of phenolic acid, flavonoids, sugars, organic acid and AsA in A. eriantha fruit were further analyzed. The phenolic compounds accounted for 32.37% of the total metabolites, including 48 phenolic acids, 60 flavonoids, 7 tannins and 20 lignans and coumarins. Correlation analysis of metabolites and transcripts showed PAL (DTZ79_15g06470), 4CL (DTZ79_26g05660 and DTZ79_29g0271), CAD (DTZ79_06g11810), COMT (DTZ79_14g02670) and FLS (DTZ79_23g14660) correlated with polyphenols. There are twenty-three metabolites belonging to sugars, the majority being sucrose, glucose arabinose and melibiose. The starch biosynthesis-related genes (AeglgC, AeglgA and AeGEB1) were expressed at lower levels compared with metabolism-related genes (AeamyA and AeamyB) in three mature fruits of three varieties, indicating that starch was converted to soluble sugar during fruit maturation, and the expression level of SUS (DTZ79_23g00730) and TPS (DTZ79_18g05470) was correlated with trehalose 6-phosphate. The main organic acids in A. eriantha fruit are citric acid, quinic acid, succinic acid and D-xylonic acid. Correlation analysis of metabolites and transcripts showed ACO (DTZ79_17g07470) was highly correlated with citric acid, CS (DTZ79_17g00890) with oxaloacetic acid, and MDH1 (DTZ79_23g14440) with malic acid. Based on the gene expression, the metabolism of AsA acid was primarily through the L-galactose pathway, and the expression level of GMP (DTZ79_24g08440) and MDHAR (DTZ79_27g01630) highly correlated with L-Ascorbic acid. Our study provides additional evidence for the correlation between the genes and metabolites involved in phenolic acid, flavonoids, sugars, organic acid and AsA synthesis and will help to accelerate the kiwifruit molecular breeding approaches.

Effect of Apple Consumption on Postprandial Blood Glucose Levels in Normal Glucose Tolerance People versus Those with Impaired Glucose Tolerance

The present study investigated the effect of apple consumption on postprandial blood glucose and insulin levels in subjects with normal versus impaired glucose tolerance. The study participants were ten healthy subjects with no glucose intolerance (normal subjects) (mean, 24.4 ± 4.8 years) and nine subjects with impaired glucose tolerance (mean, 45.2 ± 11.1 years, including 2 on insulin therapy). The test meal included white rice (148 g) and a Fuji apple (150 g). The normal subjects were randomly divided into two groups: the apple-first group, wherein the subjects consumed white rice 5 min after consuming the apple, and the rice-first group, wherein the subjects consumed an apple 5 min after consuming the white rice. Blood samples were then taken from both groups for 3 h. In addition, the subjects with impaired glucose tolerance received the same treatment as the normal subjects, with the difference being glucose level monitoring according to the order in which the apples were consumed. In the normal subjects, the Cmax of Δblood glucose and Δinsulin levels were 54.0 ± 5.0 mg/dL and 61.9 ± 7.2 µU/dL versus 46.2 ± 5.9 mg/dL and 49.8 ± 8.5 µU/dL in the rice-first and apple-first groups, respectively. The incremental area under the curve (iAUC) of insulin tended to decrease in the apple-first group. In the impaired glucose tolerance subjects, the Cmax of Δblood glucose was 75.2 ± 7.2 mg/dL in the apple-first group compared to 90.0 ± 10.0 mg/dL in the rice-first group, which was a significant difference (p < 0.05). The iAUC of blood glucose was lower in the apple-first group. Eating an apple before a meal may be a simple and effective strategy for managing the glycaemic response in individuals with impaired glucose tolerance.

Quality of ‘Hayward’ Kiwifruit in Prolonged Cold Storage as Affected by the Stage of Maturity at Harvest

The effect of ‘Hayward’ kiwifruit maturity at harvest on fruit quality during long-term storage at −0.5 °C was evaluated by harvesting the fruit several times, at different stages of maturity. The progress of maturation on the vine was monitored weekly from 136 DAFB (days after full bloom). Fruit were harvested for storage at three points and stored for 3–6 months in regular air (RA), or for 6–10 months in a controlled atmosphere (CA), with or without prestorage exposure to 1-methylcyclopropene (1-MCP). The softening rate under both storage regimes decreased with the advance in fruit maturation on the vine, as indicated by increasing soluble solids content (SSC), and declining firmness. As a result, the fruit from the first harvest (152 DAFB), which were the firmest at harvest, were the softest at the end of both storage regimes. Delaying harvest also decelerated the decline in acidity during storage, so that fruit picked last maintained the highest titratable acidity (TA) upon removal from storage. The overall fruit quality after shelf life, following prolonged storage in either RA or CA, was improved by delaying harvest to late November (ca. 200 DAFB). The harvest criteria for fruit with the best storage potential were dry matter (DM) > 17%, SSC > 7%, TA 2.0–2.6%, with more than 40% of the DM non soluble. From a commercial aspect the rule should therefore be ‘Last in, last out’ (LILO).

The comparison of biochemical composition of Actinidia kolomikta and Actinidia polygama fruits

The demand for natural products, which are rich in biologically active compositions, grows constantly. The choice and production of such products can minimize the deficit of importance for human organism components, which are contained only in plant food. The paper contains the laboratory studying results of the chemical composition of the fruits of two Actinidia Lindl. cultivars of Federal State Budgetary Scientific Institution Federal Horticultural Research Center for Breeding, Agrotechnology, and Nursery (FSBSI FSC for Horticulture) genetic collection: Actinidia kolomikta (Rupr. et Maxim.) Maxim. and Actinidia polygama (Siebold et Zucc.) Maxim. All the presented samples are grown in field conditions. The fruits were picked up in the phase of harvest maturity while ripening. The data on antioxidant activity of water and methanol extracts, the content of phenolic compounds sum, soluble solids, and titratable acids in the fruits, and on qualitative composition of secondary metabolites (organic acids, fatty acids, mono-, di- and polysaccharides) are given in the paper. The variation limits of the parameters under study depending on the sample are presented. As a result of the laboratory studies, it was stated that A. kolomikta fruits 10 times exceed A. polygama fruits on all the stated parameters. Only the results on the soluble solids content in the fruits of both cultivars are approximately at the same level (A. kolomikta > A. polygama on 1.16%). The positive correlation between antioxidant activity and the general content of polyphenols is confirmed at both cultivars. Actinidia kolomikta genotypes Chempion and Lakomka and Actinidia polygama ones Tselebnaya and Uzorchataya showed the best results. The correct individual choice of actinidia fruits that are the best ones at the biochemical composition and the content of micronutrients allows supplying the consumers with food products.

Effect on Phytochemical Content and Microbial Contamination of Actinidia Fruit after Shock Cooling and Storage

Mini kiwi fruits are tasty and contain valuable nutrients - vitamin, micro end macroelements and polyphenols. The tested cultivars (Sientiabrskaja, Geneva, Issai, Ken’s Red) belong to two species of Actinidia (A. arguta and A. kolomikta), which tolerate well the conditions of a temperate climate with negative temperatures in winter. The effect of postharvest shock cooling on fruit quality was investigated after 6 weeks of storage in CA and then after 5 days of shelf life. Shock cooling of fruit after harvest reduced adverse changes in fruit quality after storage in CA cold storage and shelf life. They were firmer, more puncture resistant, and retained more L-ascorbic acid and polyphenols. After 6 weeks of cold storage in CA, eight types of fungi and molds were found that caused the mycotoxins patulin, deoxynivalenol, and zearalenone were found in the fruit of all cultivars. Fruits of the Ken’s Red cultivar were the most firm and puncture resistant, the darkest, and contained the most anthocyanins and the least L-ascorbic acid. In contrast, fruits of the cultivar Sientaibrskaja were the least suitable for storage and transport.

Comparison of fruit morphology and nutrition metabolism in different cultivars of kiwifruit across developmental stages

Kiwifruit (Actinidia) is becoming increasingly popular worldwide due to its favorable flavour and high vitamin C content. However, quality parameters vary among cultivars. To determine the differences in quality and metabolic parameters of kiwifruit, we monitored the growth processes of 'Kuilv' (Actinidia arguta), 'Hongyang' (Actinidia chinensis) and 'Hayward' (Actinidia deliciosa). We found that 'Kuilv' required the shortest time for fruit development, while 'Hayward' needed the longest time to mature. The fruit size of 'Hayward' was the largest and that of 'Kuilv' was the smallest. Furthermore, 'Hongyang' showed a double-S shape of dry matter accumulation, whereas 'Kuilv' and 'Hayward' showed a linear or single-S shape pattern of dry matter accumulation during development. The three cultivars demonstrated the same trend for total soluble solids accumulation, which did not rise rapidly until 90-120 days after anthesis. However, the accumulation of organic acids and soluble sugars varied among the cultivars. During later fruit development, the content of glucose, fructose and quinic acid in 'Kuilv' fruit was far lower than that in 'Hongyang' and 'Hayward'. On the contrary, 'Kuilv' had the highest sucrose content among the three cultivars. At maturity, the antioxidative enzymatic systems were significantly different among the three kiwifruit cultivars. 'Hongyang' showed higher activities of superoxide dismutase than the other cultivars, while the catalase content of 'Hayward' was significantly higher than that of 'Hongyang' and 'Kuilv'. These results provided knowledge that could be implemented for the marketing, handling and post-harvest technologies of the different kiwifruit cultivars.

The Effects of Gold Kiwifruit Intake Timing with or without Pericarp on Postprandial Blood Glucose Level

The purpose of this study was to examine how gold kiwifruit pericarp (pericarp is defined as the skin of the fruit) consumption and the timing thereof affect the postprandial blood glucose profile. The study was conducted on twelve healthy volunteers (six men and six women). According to our results, the simultaneous intake of gold kiwifruit with bread and the prior intake of gold kiwifruit evidently suppressed the postprandial blood glucose elevation compared with exclusive bread intake. There was no significant difference in postprandial blood glucose changes between the ingestion of gold kiwifruit pericarp and pulp and that of gold kiwifruit pulp only. The highest postprandial blood glucose elevation was suppressed by 27.6% and the area under the blood glucose elevation curve by 29.3%, even with the exclusive ingestion of gold kiwifruit pulp. We predicted that the ingestion of both the pericarp and pulp of gold kiwifruit would reduce the postprandial blood glucose elevation to a greater extent than that of gold kiwifruit pulp only; however, there was no significant difference between the two. These results indicate that gold kiwifruit consumption significantly suppresses the postprandial blood glucose elevation regardless of pericarp presence or absence and the timing of ingestion.

The effect of cane vigour on the kiwifruit (Actinidia chinensis) and kiwiberry (Actinidia arguta) quality

Kiwifruit has not been studied as much as other well-known fruits especially when it comes to studies about plant vigour and training systems. The aim of the study was to determine the importance of cane vigour of Actinidia chinensis var. deliciosa 'Hayward' and Actinidia arguta 'Issai' in order to develop the proper pruning technique that results in the best fruit quality. In addition, the effect of storage parameters such as weight, firmness and quality of the fruit was also studied. The study showed that the fruit size and weight are lower in low vigour canes in A. arguta, in contrast to A. chinensis, where the fruit size and weight are smaller on high-vigorous canes. For A. arguta, it is recommended to choose high-vigour canes as the optimal fruit wood during pruning. In this way, the fruits will ripen more evenly. The other possibility is to perform the harvest two to three times per season to achieve a more uniform fruit quality. In the case of A. chinensis the fruit are less variable between different cane vigour, so harvesting can be done in a single picking. In A. chinensis the less vigorous canes tend to show a slightly better fruit quality.

Transcriptome sequencing and endogenous phytohormone analysis reveal new insights in CPPU controlling fruit development in kiwifruit (Actinidia chinensis)

Kiwifruit (Actinidia chinensis) is a rich nutritious fruit crop owing to a markedly higher content of vitamin C and minerals. To promote fruit set and to increase the yield of kiwifruit, forchlorfenuron (CPPU) has been widely applied. However, the molecular details regarding CPPU controlling kiwifruit development, especially at the fastest fruit growth stage, remain unknown. In the present study, we measured the effect of CPPU on developmental regulation in red-fleshed kiwifruit (Actinidia chinensis 'Hongyang'). Additionally, a cytological analysis was performed to clarify the precise changes in the cell structure of the CPPU-treated kiwifruits. Moreover, the concentration of endogenous phytohormones, including indoleacetic acid (IAA), zeatin (ZT), gibberellic acid 3 (GA3), and abscisic acid (ABA), were measured by Enzyme-linked Immunosorbent Assay (ELISA). Furthermore, RNA-Seq was performed to dissect the complicated molecular mechanisms, with a focus on biosynthesis, metabolism, and signaling compounds, such as endogenous hormones, sugars, and L-ascorbic acid. Our results demonstrated that CPPU treatment not only regulates the size and weight of a single fruit but also improves the quality in 'Hongyang' kiwifruit through the accumulation of both soluble sugar and vitamin C. It was also seen that CPPU regulates kiwifruit development by enhancing cell expansion of epidermal cells and parenchyma cells, while, promoting cell division of subepidermal cells. Additionally, CPPU significantly increased the gibberellin and cytokinin biosynthetic pathway and signaling, while repressing auxin and ABA biosynthetic pathway; thus, signaling plays an essential role in CPPU controlling kiwifruit development. Notably, transcriptomic analysis revealed that a total of 2244 genes, including 352 unannotated genes, were differentially expressed in kiwifruits because of CPPU treatment, including 127 transcription factors. These genes are mainly enriched in plant hormone signal transduction, photosynthesis, MAPK signaling pathway, starch and sucrose metabolism, and phenylpropanoid biosynthesis. Overall, our results highlight that CPPU regulation of kiwifruit development is mainly associated with an antagonistic and/or synergistic regulatory role of endogenous phytohormones, and enhancing the energy supply. This provides new insights into the molecular details of CPPU controlling kiwifruit development at the fastest fruit growth stage, which is of agricultural importance for kiwifruit breeding and crop improvement.

Changes in phenolics, soluble solids, vitamin C, and antioxidant capacity of various cultivars of hardy kiwifruits during cold storage

Hardy kiwifruits (Actinidia arguta) contain various bioactive compounds such as vitamin C and phenolics and can withstand cold temperatures. Changes in soluble solid, vitamin C, total phenolic, and total flavonoid content, and antioxidant capacity of three cultivars of hardy kiwifruits (A. arguta × A. deliciosa cv. Mansu, A. arguta cv. Haeyeon, and A. arguta cv. Chiak) were comparatively evaluated for 8 weeks of storage at 1 ± 0.5 °C. After the 8 weeks of storage, soluble solid content of three cultivars increased, whereas their vitamin C content decreased. Throughout this storage period, total phenolic and flavonoid content of cv. Mansu and cv. Haeyeon remained the same, while antioxidant capacity of these two cultivars also remained similar but with slightly more variations. Cv. Chiak, however, showed a decrease in total phenolic and flavonoid content and antioxidant capacity. These results suggest that cold storage of the hardy kiwifruits maintains levels of bioactive compounds.

Profiles of Sugar and Organic Acid of Fruit Juices: A Comparative Study and Implication for Authentication

A comparison of sugar and organic acid profiles among different fruit juices (including apple, pear, peach, grape, sweet cherry, strawberry, and blueberry with various varieties) was performed to assess the possibility for authentication coupled with chemometrics. It was found that the distribution of each sugar and organic acid in juices showed some specific characteristics related to fruit species, despite the fact that great differences in the content existed among different varieties. Sucrose was the most abundant sugar in peach juice, accounting for 58.26–77.11% of the total sugar content. However, in grape, blueberry, and sweet cherry juice, glucose and fructose were the predominant sugars. Pear juice contained the highest level of sorbitol, which contributed to 15.02–43.07% of the total sugar content. Tartaric acid was detected only in grape juice among the seven species of fruit juice, with a proportion of 57.95–89.68% in the total acid content. Malic acid was the predominant organic acid in apple and sweet cherry juice, accounting for 69.92–88.30% and 97.51–98.73% of the total acid content of each species. Citric acid was the predominant organic acid in strawberry and blueberry juice, which contributed to 62.39–83.73% and 73.36–89.56% of the total acid content of each species. With the aid of principal component analysis and linear discriminant analysis (LDA), the juice samples could be successfully classified according to fruit species by using the sugar and/or organic acid composition as analytical data. Combination of sugar and organic acid composition gave the best differentiation of these seven species of juices, with a 100% correct classification rate for both the original and the cross-validation method in LDA. Adding malic/citric into the dataset of the organic acid content may also improve the differentiation effect. Furthermore, the adulteration of sweet cherry juice, blueberry juice, raspberry juice, and grape juice with apple juice, pear juice, or peach juice could also be distinguished from their corresponding pure juices based on sugar and organic acid composition by LDA.

Correlation between fruit weight and nutritional metabolism during development in CPPU-treated Actinidia chinensis 'Hongyang'

Forchlorfenuron, N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU), is often used to promote fruit growth and improve production. The role of CPPU in kiwifruit growth has been established. However, the correlation between fruit weight and nutritional metabolism during development after CPPU treatments remains largely undetermined. Here, we surveyed the variations in weight and nutrient components of the 'Hongyang' kiwifruit (Actinidia chinensis) when CPPU was sprayed on fruit 25 days after anthesis. The CPPU application did not significantly influence the dry matter, soluble solids, starch, vitamin C or protein concentrations. However, the fresh weight, length and maximum diameter were significantly increased compared with the control. Moreover, in fruit of the same developmental stage, the fructose, glucose and soluble sugar levels increased after the CPPU treatment, compared with the control. On the contrary, citric, quinic and titratable acid concentrations decreased. However, a correlation analysis between fresh weight and the nutritional contents revealed that CPPU did not affect the concentrations of the most abundant organic acids (quinic and citric) and sugars (glucose, fructose and sucrose), compared with control fruit of the same weight. Therefore, CPPU applications enhance 'Hongyang' kiwifruit weight/size. However, there were no significant differences in the nutritional qualities of treated and untreated fruit having the same weights.

Bioactivity, phytochemical profile and pro-healthy properties of Actinidia arguta: A review

Hardy kiwi (Actinidia arguta) is a climbing, perennial and dioecious vine from Actinidiaceae family, native from Asia and valued as ornamental and traditional medicine. In the last decade, the growing interest as fruit-bearing plant encourage the expanding cultivation of A. arguta mainly to fruits production, particularly in Europe and North America. A. arguta plants have an extensive range ofbioactive compoundsthat can be obtained from different botanical structures, such as fruits, leaves, flowers and stems. These bioactive molecules, with well-recognized health-promoting properties, include phenolic compounds, minerals, carbohydrates or even volatile substances, with a great potential to be used in several formulations of food products. Phytochemical studies on this plant reported hypoglycemic effects as well as antioxidant and anti-inflammatory activities, among others. The traditional uses ofA. arguta have been experimentally proved byin vitroandin vivostudies, in which its bioactivities were associated to its phytochemical composition. This review aims to assess and summarize the phytochemical and healthy properties ofthe different botanical parts of A. arguta, describing their bioactive composition and exploring it potential functional properties on foodstuffs.

Nutritional component analyses of kiwifruit in different development stages by metabolomic and transcriptomic approaches

BACKGROUND

Metabolites in kiwifruit greatly influence nutritional values; however, the dynamic changes in nutrient composition and the gene expression level of yellow kiwifruit have not been studied so far. To investigate the types and accumulation patterns of metabolites, a metabolomics approach utilizing liquid chromatography-electrospray ionization mass spectrometry and transcriptomics were used to analyze the yellow flesh of kiwifruit cultivar 'jinshi 1' collected at different stages of days after full bloom.

RESULTS

In total, 285 metabolites were identified over the kiwifruit developmental stages. The composition of the metabolites of kiwifruit at different stages of development was different. The organic acids contents and their derivatives were higher at the initial stage of development and then gradually decreased. The lipids and amino acids contents fluctuated at different stages of development but did not change significantly. Transcript profiles throughout yellow kiwifruit development were constructed and analyzed, with a focus on the biosynthesis and metabolism of compounds such as sugars, organic acids and ascorbic acid, which are indispensable for the development and formation of quality fruit. The transcript levels of genes involved in sucrose and starch metabolism were consistent with the change in soluble sugar and starch content throughout kiwifruit development. The metabolism of ascorbic acid was primarily through the l-galactose pathway.

CONCLUSION

Our metabolome and transcriptome approach identified dynamic changes in five types of nutrient metabolite levels, and correlations among such levels, in developing fruit. The results provide information that can be used by metabolic engineers and molecular breeders to improve kiwifruit quality. © 2020 Society of Chemical Industry.

Characterization of Organic Acid Metabolism and Expression of Related Genes During Fruit Development of Actinidia eriantha 'Ganmi 6'

Studies on organic acid metabolism have been mainly concentrated on the fruit, whereas, few have focused on the mechanism of high organic acids content in the fruit of Actinidia eriantha. Fruits of 'Ganmi 6' harvested at eleven developmental periods were used as materials. The components and content of organic acids were determined by high-performance liquid chromatography (HPLC) system, the activities of the related enzyme were detected, and gene expression levels were measured by quantitative real-time PCR (qRT-PCR). Components of ascorbic acid (AsA) and eight kinds of organic acids were detected. These results showed that quinic acid and citric acid were the main organic acids in the fruit of 'Ganmi 6'. Correlation analysis showed that NADP-Quinate dehydrogenase (NADP-QDH), NADP-Shikimate dehydrogenase (NADP-SDH), and Cyt-Aconitase (Cyt-Aco) may be involved in regulating organic acids biosynthesis. Meanwhile, the SDH gene may play an important role in regulating the accumulation of citric acid. In this study, the activities of NADP-SDH, Mit-Aconitase (Mit-Aco), and NAD-Isocitrate dehydrogenase (NAD-IDH) were regulated by their corresponding genes at the transcriptional level. The activity of Citrate synthase (CS) may be affected by post-translational modification. Our results provided new insight into the characteristics of organic acid metabolism in the fruit of A. eriantha.

Isolation and Selection of Non-Saccharomyces Yeasts Being Capable of Degrading Citric acid and Evaluation Its Effect on Kiwifruit Wine Fermentation

High citric acid content in kiwifruit wine would lead to bad sensory experience and quality deterioration. It is opportune and crucial to develop an appropriate and feasible method to degrade citric acid for kiwifruit wine. The non-Saccharomyces yeasts confirmed to have the ability to degrade citric acid were screened and used in kiwifruit wine fermentation in the study. A representative number of 23 yeasts with a strong citric acid degradation ability was identified by molecular approaches. JT-1-3, identified to be Pichia fermentans, was preferred for high citric acid degradation and strong stress resistance in association with RV002 (commercial Saccharomyces cerevisiae). Then it was pure-cultured in kiwifruit juice, and the results indicated that citric, malic and tartaric acids declined significantly from 12.30, 3.09 and 0.61 g/L to 11.00, 2.02 and 0.41 g/L after fermentation, respectively, resulting in the significant decrease in total acid in kiwifruit wine. The analytical profiles for amino acids and volatile compounds showed that Pichia fermentans JT-1-3 could improve amino acids’ proportion and increase the volatile compounds of alcohols, esters and phenols. This work indicated that JT-1-3 has great potential to be applied for fruit wine with high level citric acid.

Chemical composition and bioactive properties of byproducts from two different kiwi varieties

Kiwis are an example of fruits with excellent bioactive properties worldwide appreciated and consumed generating tons of waste. Thus, the objective of this work was to compare two varieties of kiwi: Actinidia deliciosa cv. "Hayward" (green) and Actinidia spp. (red) regarding the nutritional value of their pulps, chemical composition and bioactivities of each pulp and peel. The results revealed that pulps have a high water content and low amount of other macronutrients. Both parts of red kiwi presented the highest tocopherols content and red kiwi pulp presented the highest content in ascorbic acid. In general, the peels exhibited the highest antioxidant activity and green kiwi peels showed cytotoxicity and anti-inflammatory activity, which could be related to its higher content in phenolic compounds, especially B-type (epi)catechin dimer. Therefore, kiwi components currently underutilized may be indicated as a source of natural functionalizing ingredients with several benefits for human health.

The nutritional and health attributes of kiwifruit: a review

PURPOSE

To describe the nutritional and health attributes of kiwifruit and the benefits relating to improved nutritional status, digestive, immune and metabolic health. The review includes a brief history of green and gold varieties of kiwifruit from an ornamental curiosity from China in the 19th century to a crop of international economic importance in the 21st century; comparative data on their nutritional composition, particularly the high and distinctive amount of vitamin C; and an update on the latest available scientific evidence from well-designed and executed human studies on the multiple beneficial physiological effects. Of particular interest are the digestive benefits for healthy individuals as well as for those with constipation and other gastrointestinal disorders, including symptoms of irritable bowel syndrome. The mechanisms of action behind the gastrointestinal effects, such as changes in faecal (stool) consistency, decrease in transit time and reduction of abdominal discomfort, relate to the water retention capacity of kiwifruit fibre, favourable changes in the human colonic microbial community and primary metabolites, as well as the naturally present proteolytic enzyme actinidin, which aids protein digestion both in the stomach and the small intestine. The effects of kiwifruit on metabolic markers of cardiovascular disease and diabetes are also investigated, including studies on glucose and insulin balance, bodyweight maintenance and energy homeostasis.

CONCLUSIONS

The increased research data and growing consumer awareness of the health benefits of kiwifruit provide logical motivation for their regular consumption as part of a balanced diet. Kiwifruit should be considered as part of a natural and effective dietary strategy to tackle some of the major health and wellness concerns around the world.

The Nutritional and Health Benefits of Kiwiberry (Actinidia arguta) - a Review

The kiwiberry (Actinidia arguta) is a new product on the market that is enjoying growing consumer acceptance around the world. This widespread interest has created increased demand for identification of the kiwiberry's nutritional health benefits. Containing over 20 essential nutrients and a range of vitamins, the kiwiberry comes near the top of fruits classed as superfoods. It is one of the richest sources of vitamin C with up to 430 mg/100 g fresh weight (FW) and is considered the richest dietary source of myo-inositol (up to 982 mg/100 g FW). The kiwiberry is also one of the richest sources of lutein (up to 0.93 mg/100 g FW) in commonly consumed fruit. Furthermore, containing up to 1301.1 mg/100 g FW phenolics and significant amounts of the essential minerals of potassium, calcium and zinc, the kiwiberry rates very highly as a 'healthy food'. The type and number of this fruit's medicinally promising nutrients have motivated ongoing investigations into its antioxidant, anti-tumour and anti-inflammatory properties. Early research has pointed to the kiwiberry being a very promising treatment for some cancers and health issues involving the gastrointestinal system, hypercholesterolemia and certain cancers. A pharmaceutical composition of A. arguta, A. kolomikta, and A. polygama extracts has already been registered for the prevention and treatment of some immune (inflammatory) mediated diseases, as well as the treatment of some non-allergic inflammatory diseases. This paper reviews and highlights the limited nutritional and therapeutic information currently available on the kiwiberry, a minor fruit possessing such major properties.

Characterization of metabolites in different kiwifruit varieties by NMR and fluorescence spectroscopy

It is known from our previous studies that kiwifruits, which are used in common human diet, have preventive properties of coronary artery disease. This study describes a combination of ¹H NMR spectroscopy, multivariate data analyses and fluorescence measurements in differentiating of some kiwifruit varieties, their quenching and antioxidant properties. A total of 41 metabolites were identified by comparing with literature data Chenomx database and 2D NMR. The binding properties of the extracted polyphenols against HSA showed higher reactivity of studied two cultivars in comparison with the common Hayward. The results showed that the fluorescence of HSA was quenched by Bidan as much as twice than by other fruits. The correlation between the binding properties of polyphenols in the investigated fruits, their relative quantification and suggested metabolic pathway was established. These results can provide possible application of fruit extracts in pharmaceutical industry.

Agronomic Trait Variations and Ploidy Differentiation of Kiwiberries in Northwest China: Implication for Breeding

Polyploid plants often have higher biomass and superior crop qualities. Breeders therefore search for crop germplasm with higher ploidy levels; however, whether higher ploidy levels are associated with better performance remains unclear. Actinidia arguta and related species, whose commercialized fruit are referred to as kiwiberries, harbor a series of ploidy races in nature, offering an opportunity to determine the link between ploidy levels and agronomic traits. In the present study, we determined the ploidy levels of A. arguta var. arguta, A. arguta var. giraldii, and A. melanandra in 16 natural populations using flow cytometry, and examined 31 trait variations in fruits, leaves and flowers by field observations, microscopic examination and laboratory analyses. Our results showed that octaploid and decaploid A. arguta var. giraldii had larger dimension of leaves than tetraploid A. arguta var. arguta and A. melanandra, but their fruits were significantly smaller. In addition, A. arguta var. giraldii (8x and 10x) had higher contents of nutrients such as ascorbic acid and amino acids; however, some important agronomic traits, including the content of total sugar and total acid, were significantly lower in the octaploids and decaploids. Moreover, octaploids and decaploids did not result in greater ecological adaptability for the challenging environments and climates. In conclusion, the differentiation of ecological adaptability and traits among natural kiwiberries' cytotypes suggested that higher ploidy levels are not inevitably advantageous in plants. The findings of A. arguta and related taxa in geographical distribution and agronomic trait variations will facilitate their germplasm domestication.

Comprehensive Transcriptome Profiling Reveals Long Noncoding RNA Expression and Alternative Splicing Regulation during Fruit Development and Ripening in Kiwifruit (Actinidia chinensis)

Genomic and transcriptomic data on kiwifruit (Actinidia chinensis) in public databases are very limited despite its nutritional and economic value. Previously, we have constructed and sequenced nine fruit RNA-Seq libraries of A. chinensis "Hongyang" at immature, mature, and postharvest ripening stages of fruit development, and generated over 66.2 million paired-end and 24.4 million single-end reads. From this dataset, here we have identified 7051 long noncoding RNAs (lncRNAs), 29,327 alternative splicing (AS) events and 2980 novel protein-coding genes that were not annotated in the draft genome of "Hongyang." AS events were demonstrated in genes involved in the synthesis of nutritional metabolites in fruit, such as ascorbic acids, carotenoids, anthocyanins, and chlorophylls, and also in genes in the ethylene signaling pathway, which plays an indispensable role in fruit ripening. Additionally, transcriptome profiles and the contents of sugars, organic and main amino acids were compared between immature, mature, and postharvest ripening stages in kiwifruits. A total of 5931 differentially expressed genes were identified, including those associated with the metabolism of sugar, organic acid, and main amino acids. The data generated in this study provide a foundation for further studies of fruit development and ripening in kiwifruit, and identify candidate genes and regulatory elements that could serve as targets for improving important agronomic traits through marker assisted breeding and biotechnology.

In vitro characterisation of the fermentation profile and prebiotic capacity of gold-fleshed kiwifruit

A new Actinidia chinensis gold-fleshed kiwifruit cultivar 'Zesy002' was tested to investigate whether it could positively modulate the composition of the human colonic microbiota. Digested Zesy002 kiwifruit was added to in vitro pH-controlled anaerobic batch fermenters that were inoculated with representative human faecal microbiota. Alterations to the gut microbial ecology were determined by 16S rRNA gene sequencing and metabolic end products were measured using gas chromatography and liquid chromatography - mass spectrometry. Results indicated a substantial shift in the composition of bacteria within the gut models caused by kiwifruit supplementation. Zesy002 supplemented microbiota had a significantly higher abundance of Bacteroides spp., Parabacteroides spp. and Bifidobacterium spp. after 48 h of fermentation compared with the start of the fermentation. Organic acids from kiwifruit were able to endure simulated gastrointestinal digestion and were detectable in the first 10 h of fermentation. The fermentable carbohydrates were converted to beneficial organic acids with a particular predilection for propionate production, corresponding with the rise in Bacteroides spp. and Parabacteroides spp. These results support the claim that Zesy002 kiwifruit non-digestible fractions can effect favourable changes to the human colonic microbial community and primary metabolites, and demonstrate a hitherto unknown effect of Zesy002 on colonic microbiota under in vitro conditions.

The composition and nutritional value of kiwifruit

Understanding the nutrient composition of kiwifruit is central to discussions of the nutritional value and potential health benefits of kiwifruit. Until recently, there were only limited validated data providing extensive compositional information available as reference values for common commercial cultivars. As a genus, Actinidia is diverse in both form and composition; however, there are several notable compounds that, within the context of fruit, are the signature of Actinidia: vitamin C, actinidin, fiber, vitamin E, and for selected cultivars, the persistence of chlorophyll in the mature fruit. Kiwifruit is also known as a nutritionally dense fruit, based on the level of nutrients present. The high amount of vitamin C in kiwifruit is the primary driver of such nutritional scores. Recently, a new approach to estimating the true energy value of kiwifruit has shown that kiwifruit delivers less available energy relative to other foods than is assumed based on traditional measures of food energy content. This, together with the key nutritional elements of kiwifruit, supports its position as a highly nutritious, low-calorie fruit with the potential to deliver a range of health benefits.

Applications of NMR metabolomics to the study of foodstuffs: truffle, kiwifruit, lettuce, and sea bass

In this review, four examples of the NMR metabolomic approach to foodstuff investigation are reported. Different types of foodstuff of different origin (namely truffle, kiwifruit, lettuce, and sea bass), with different metabolite composition, processing, and storage procedures have been chosen to demonstrate the versatility and potentiality of NMR in the foodstuff analysis. Fundamental aspects of NMR methodology such as sample preparation, metabolites extraction, quantitative elaboration of spectral data, and statistical analysis have been described. Metabolic profilings of aqueous and/or organic extracts as obtained by one- and two-dimensional NMR experiments have been reported together with the results obtained from their statistical elaboration. Discrimination between wild and farmed sea bass and between genetically modified and wild lettuces as well as changes in the kiwifruit metabolic profiles monitored over the season have been investigated. For each foodstuff, some complementary findings provided by other analytical methods are also described to underline the importance of different analytical approaches to explore specific aspects related to foodstuff.

Changes in quinic acid metabolism during fruit development in three kiwifruit species

Kiwifruit are novel in that they contain high levels of quinic acid (1-2% w/w), which contributes to the flavour, sugar/acid balance and health-giving properties of the fruit. In a study of quinic acid storage and metabolism in three kiwifruit species (Actinidia chinensis Planch. var. chinensis, Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa and Actinidia arguta (Sieb. et Zucc.) Planch. ex Miq. var. arguta) quinic acid accumulation occurred principally in the early stages (<60 days after anthesis; (DAA)) of fruit development. The present study established that there are separate quinate dehydrogenase (QDH) and shikimate dehydrogenase (SDH) activities in kiwifruit, probably representing different proteins. Quinate dehydrogenase activity was at a maximum around the time of greatest quinic acid accumulation and declined markedly in late fruit development, and was also higher in the species that accumulated the largest amounts of quinic acid (A. chinensis and A. deliciosa). In contrast, SDH activity was highest in the early stages of fruit development and only declined to 30-50% at later stages of fruit development in all three species. Dehydroquinate synthase gene expression levels measured by quantitative real-time PCR showed a high level in the early season, which was sustained through the mid-season. The quantitative real-time PCR results for a kiwifruit EST that had homology to chloroplastic isoforms of SDH showed an induction in the middle to late season; therefore, the high level of SDH activity in the early season (<30 DAA) may have resulted from the expression of a cytosolic isoform of the enzyme. The results are also consistent with the relative levels of the bifunctional dehydroquinate dehydratase/SDH enzyme and QDH enzyme controlling the accumulation and utilisation of quinic acid in kiwifruit.