COMPOSITION OF MAJOR FLAVANONE GLYCOSIDES AND ANTIOXIDANT CAPACITY OF THREE CITRUS VARIETIES

This paper reported on the composition of major flavanone glycosides (FGs) and antioxidant capacity of three Chinese citrus varieties during maturity, namely, Ponkan (P; citrus poonensis Hort. ex Tanaka), Satsuma mandarin (S; citrus unshiu Marc.) and Huyou (H; citrus paradisi Macf. cv. Changshanhuyou). The results showed that citrus peel is a rich source of FGs. Total penolics contents (TPC) of methanol extract of P, S and H were determined. The total antioxidant capacity (TAC) of P, S and H extracts was compared based on vitamin C equivalent antioxidant capacity by 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2, 2 ' -azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS ^·+ ), reducing power and ferric reducing antioxidant power (FRAP) assay. Phenolic compounds may contribute a lot to TAC of fresh fruits, especially for unripe fruits. The correlations among TPC, DPPH·, ABTS ^·+ , reducing power and FRAP assay were rather high ( P <  0.05).

PRACTICAL APPLICATION

Citrus flavonoids are abundant in citrus fruits, especially FGs, such as hesperidin and naringin; and they are attracting more attentions for their biological properties and health benefits. The sun-dried citrus peels ( chenpi ) are usually used in the traditional Chinese medicine for high content of hesperidin. Investigation on the composition of FGs in peel and edible part of citrus fruits during maturity is necessary to establish a database for the future use in health foods and ingredients. Meanwhile, four methods were employed simultaneously to achieve a comprehensive evaluation on the antioxidant capacity of the three citrus varieties. The high antioxidant potential of the three selected citrus varieties made them desirable for dietary prevention of cardiovascular and other diseases.     

Biochemistry and biological functions of citrus limonoids

Abstract

Limonoids are one of bitter principles in citrus juices. Excessive bitterness lowers the quality and value of citrus juices. Nomilin is considered to be the precursor of all other limonoids accumulated in Citrus and related species. It is biosynthesized from acetate via the terpenoid biosynthetic pathway in the phloem region of stems and then translocated to the leaves, fruit tissues, peels, and seeds where it is further metabolized to other limonoids. The citrus limonoid aglycones are then glucosidated by limonoid UDP‐D‐glucose transferase in maturing fruit tissues and seeds. These limonoid glucosides are accumulated in such high concentrations that they are one of major secondary metabolites in citrus fruit tissues, and they play an important role in fruit quality and possibly in human health. Research on creation of transgenic citrus trees that produce fruits free of the limonoid bitterness problem is in progress. Limonoids have been shown to induce glutathione S‐transferase activity and inhibit the formation of certain chemically induced carcinogenesis in laboratory animals. Some of the limonoids possess antifeedant activity against insects, suggesting that one of the biological functions of limonoids in plants is pest control. The citrus limonoids are unique for many species and varieties, and make excellent taxonomic markers. Thus, limonoids are important citrus constituents to citrus growers, processors, breeders, and the consumer.     

Juice blends--a way of utilization of under-utilized fruits, vegetables, and spices: a review

The post-harvest shelf life of maximum of fruits and vegetables is very limited due to their perishable nature. In India more then 20-25 percent of fruits and vegetables are spoiled before utilization. Despite being the world's second largest producer of fruits and vegetables, in India only 1.5 percent of the total fruits and vegetables produced are processed. Maximum amounts of fruit and vegetable juices turn bitter after extraction due to conversion of chemical compounds. In spite of being under utilized, the utilization of highly nutritive fruits and vegetables is very limited due to high acidity, astringency, bitterness, and some other factors. While improving flavor, palatability, and nutritive and medicinal value of various fruit juices such as aonla, mango, papaya, pineapple, citrus, ber, pear, apple, watermelon, and vegetables including bottle gourd, carrot, beet root, bitter gourd, medicinal plants like aloe vera and spices can also be used for juice blending. All these natural products are valued very highly for their refreshing juice, nutritional value, pleasant flavor, and medicinal properties. Fruits and vegetables are also a rich source of sugars, vitamins, and minerals. However, some fruits and vegetables have an off flavor and bitterness although they are an excellent source of vitamins, enzymes, and minerals. Therefore, blending of two or more fruit and vegetable juices with spices extract for the preparation of nutritive ready-to-serve (RTS), beverages is thought to be a convenient and economic alternative for utilization of these fruits and vegetables. Moreover, one could think of a new product development through blending in the form of a natural health drink, which may also serve as an appetizer. The present review focuses on the blending of fruits, under-utilized fruits, vegetables, medicinal plants, and spices in appropriate proportions for the preparation of natural fruit and vegetable based nutritive beverages.     

Control of citrus green and blue molds by Chinese propolis

Green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, are economically important postharvest diseases of citrus fruits. In this study, Chinese propolis ethyl acetate extract (PEAE) was evaluated to control P. digitatum and P. italicum on postharvest citrus fruits. The results indicated PEAE strongly inhibited mycelia growth and induced hyphae prominent abnormal morphological alterations. Also, PEAE had strong detrimental effect on spore germination of the tested pathogens in a concentrationdependent manner. For in vivo tests, PEAE could both reduce decay caused by P. digitatum and P. italicum respectively in wound-inoculated fruit and naturally infected fruit; meanwhile, no negative influences on the overall quality of the citrus fruits were observed with PEAE treatment. Therefore, PEAE could be used as a natural antifungal agent to control citrus blue and green mold.     

Limonoids as cancer chemopreventive agents

Nutritional research on the health benefits of substances in plant foods has recently advanced to a new stage. The research frontier has moved from study of classical vitamin deficiency diseases to study of the thousands of phytochemicals that may have important physiological effects. Recent research suggests that citrus fruit consumers may be getting another health benefit from orange juice and other citrus products called limonoids, which appear to possess substantial anticancer activity. Limonoids are highly oxidized triterpenes present in Rutaceae and Maliaceae families. Several citrus limonoids have recently been subjected to anticancer screening utilizing laboratory animals and human breast cancer cells. The experimental results described that citrus limonoids may provide substantial anticancer actions. The compounds have been shown to be free of toxic effects in animal models, so potential exists for the use of limonoids against human cancer in either natural fruits, in citrus fortified with limonoids, or in purified forms of specific limonoids. Although the initial studies are very promising they have been conducted primarily with in vitro cell culture and animal models. Thus, research is needed to determine whether the limonoids may be useful in preventing or treating cancer in humans. Copyright © 2005 Society of Chemical Industry     

Application of Sensory Evaluation,HS‐SPME GC‐MS,E‐Nose,and E‐Tongue for Quality Detection in Citrus Fruits

In this study, electronic tongue (E‐tongue), headspace solid‐phase microextraction gas chromatography‐mass spectrometer (GC‐MS), electronic nose (E‐nose), and quantitative describe analysis (QDA) were applied to describe the 2 types of citrus fruits (Satsuma mandarins [Citrus unshiu Marc.] and sweet oranges [Citrus sinensis {L.} Osbeck]) and their mixing juices systematically and comprehensively. As some aroma components or some flavor molecules interacted with the whole juice matrix, the changes of most components in the fruit juice were not in proportion to the mixing ratio of the 2 citrus fruits. The potential correlations among the signals of E‐tongue and E‐nose, volatile components, and sensory attributes were analyzed by using analysis of variance partial least squares regression. The result showed that the variables from the sensor signals (E‐tongue system and E‐nose system) had significant and positive (or negative) correlations to the most variables of volatile components (GC‐MS) and sensory attributes (QDA). The simultaneous utilization of E‐tongue and E‐nose obtained a perfect classification result with 100% accuracy rate based on linear discriminant analysis and also attained a satisfying prediction with high coefficient association for the sensory attributes (R² > 0.994 for training sets and R² > 0.983 for testing sets) and for the volatile components (R² > 0.992 for training sets and R² > 0.990 for testing sets) based on random forest. Being easy‐to‐use, cost‐effective, robust, and capable of providing a fast analysis procedure, E‐nose and E‐tongue could be used as an alternative detection system to traditional analysis methods, such as GC‐MS and sensory evaluation by human panel in the fruit industry.     

Antioxidant actions and phenolic and vitamin C contents of common Mauritian exotic fruits

Seventeen commonly consumed exotic fruits from Mauritius were analysed for their antioxidant capacity, total phenolics, proanthocyanidins, flavonoids and vitamin C content. Two independent methods were used to evaluate the antioxidant potential of total fruit extracts. The antioxidant activities of the fruits ranged from 1 to 47 µmol Trolox equivalent antioxidant capacity (TEAC) g^?1 fresh weight and from 0.3 to 34 micro/mol g fresh weight (FRAP) g^?1 fresh weight. Total phenolics in the fruits ranged from 118 to 5638 µg g^?1 fresh weight, proanthocyanidins from 7 to 2561 µg g^?1 fresh weight, flavonoids from 21 to 712 µg g^?1 fresh weight and vitamin C content from 8 to 1426 µg g^?1 fresh weight. There were strong correlations between antioxidant activity (assessed by both TEAC and FRAP) and total phenolics and proanthocyanidins. Flavonoids seemed to contribute less to the antioxidant potential of the fruits, while very poor correlations were observed between ascorbate content and antioxidant activity. The highest antioxidant capacities were observed in red and yellow Psidium cattleianum Sabine ‘Chinese guava’, sweet and acid Averrhoa carambola L ‘starfruit’, Syzygium cumini L Skeels ‘jamblon’ and white Psidium guajava L ‘guava’. These fruits were also characterised by high levels of total phenolics. Mauritian exotic fruits are thus a significant source of phenolic antioxidants, which may have potential beneficial effects on health. Copyright © 2003 Society of Chemical Industry     

Nutrient components,health benefits,and safety of litchi (Litchi chinensis Sonn.): A review

Litchi (Litchi chinensis Sonn.) is a tropical to subtropical fruit that is widely cultivated in more than 20 countries worldwide. It is normally consumed as fresh or processed and has become one of the most popular fruits because it has a delicious flavor, attractive color, and high nutritive value. Whole litchi fruits have been used not only as a food source but also for medicinal purposes. As a traditional Chinese medicine, litchi has been used for centuries to treat stomach ulcers, diabetes, cough, diarrhea, and dyspepsia, as well as to kill intestinal worms. Both in vitro and in vivo studies have indicated that whole litchi fruits exhibit antioxidant, hypoglycemic, hepatoprotective, hypolipidemic, and antiobesity activities and show anticancer, antiatherosclerotic, hypotensive, neuroprotective, and immunomodulatory activities. The health benefits of litchi have been attributed to its wide range of nutritional components, among which polysaccharides and polyphenols have been proven to possess various beneficial properties. The diversity and composition of litchi polysaccharides and polyphenols have vital influences on their biological activities. In addition, consuming fresh litchi and its products could lead to some adverse reactions for some people such as pruritus, urticaria, swelling of the lips, swelling of the throat, dyspnea, or diarrhea. These safety problems are probably caused by the soluble protein in litchi that could cause anaphylactic and inflammatory reactions. To achieve reasonable applications of litchi in the food, medical and cosmetics industries, this review focuses on recent findings related to the nutrient components, health benefits, and safety of litchi.     

Citrus fruits — varieties,chemistry, technology,and quality evaluation. Part I: Varieties,production, handling,and storage

In part I of this comprehensive critical review on citrus fruits, the origin, botany, and classification are briefly discussed. The present status of citrus breeding with the objectives of overcoming the serious problems of die‐back and other disastrous diseases, and of producing varieties having a long harvesting period and giving a higher yield of high quality fruits, have been critically reviewed. Factors affecting the fruit quality such as rootstock, climate, and nutrition are reviewed generally with reference to established types of citrus fruits. World citrus production data has been carefully collected and presented both country‐wise and fruit‐wise to show the enormous growth and potential. Changes in composition during growth and maturation are presented with the view to fixing maturity and quality parameters and standards. Harvesting, handling, transportation, and storage aspects have been reviewed from the standpoint of optimal maintenance of quality of fruits intended for processing as well as for sale as fresh table fruit. The current problems that demand early solution have been highlighted. The succeeding parts will review chemistry, processing, and evaluation of quality.     

Gac Fruit: Nutrient and Phytochemical Composition,and Options for Processing

Momordica cochinchinensis Spreng or Gac fruits are rich in nutrients, including carotenoids, fatty acids, vitamin E, polyphenol compounds, and flavonoids. Medicinal compounds are also found in the seeds, but the benefits of traditional preparations from these need to be clarified. The plant has the potential to be a high-value crop, particularly as parts of the fruit can be processed into nutrient supplements and/or natural orange and yellow colorants. However, the plant remains underutilized. There is limited information on its requirements in production, and the processing of health products from the fruits is a relatively new area of endeavor. The versatility of the fruit is highlighted through processing options outlined for fruit aril, seeds, pulp, and skin into powders and/or encapsulated oil products. These Gac fruit products will have the potential to be utilized in a range of foods such as pasteurized juice and milk beverages, glutinous rice, yogurt, pasta, and sauces.     

Decontamination of Microorganisms and Pesticides from Fresh Fruits and Vegetables: A Comprehensive Review from Common Household Processes to Modern Techniques

Fresh fruits and vegetables are a rich source of micronutrients. However, many foodborne illnesses have been linked to the consumption of fresh fruits and vegetables as they are reported to harbor contaminants such as microorganisms and pesticides. Recently reported foodborne outbreaks have been linked to a diverse group of fruits and vegetables due to the presence of various pathogens including Salmonella, Escherichia coli, and Listeria monocytogenes. Also, the increased use of pesticides has resulted in the deposition of chemical residues on the surface of fruits and vegetables, which has led to the adverse health conditions such as cancer, birth defects, and neurodevelopmental disorders. Fresh commodities are subjected to various treatments to prevent or minimize these outbreaks, and the main targets of such treatments have been the elimination of pathogens and degradation of toxic chemical residues. Here, we have discussed various decontamination methods including simple household washing, chemical treatments, and modern technologies with their mode of action for microbial and pesticide removal. The simple household processes are not very effective in the removal of pathogenic organisms and pesticides. The use of modern techniques like cold plasma, ozone, high hydrostatic pressure, and so on, showed better efficacy in the removal of microorganisms and pesticides. However, their industrial use is limited considering high installation and maintenance cost. In this review, we suggest combined methods based on their mode of decontamination and suitability for a selected fruit or vegetable for effective decontamination of microbes and pesticide together to reduce the treatment cost and enhance food safety.     

Effect of increasing manganese concentration in nutrient solution on the antioxidant activity,vitamin C,lycopene and polyphenol contents of tomato fruit

ABSTRACT

This study evaluated the effect of increasing manganese (Mn) nutrition on the content of antioxidative compounds such as vitamin C, lycopene and polyphenols, and the antioxidant activity of tomato (Lycopersicon esculentum Mill., cvs ‘Alboney F1’ and ‘Emotion F₁’) fruit. Plants were grown in rockwool using a nutrient solution with the following content of Mn (mg dm^–3): 0.0, 0.3, 0.6, 1.2, 2.4, 4.8, 9.6 and 19.2. The level of vitamin C and lycopene decreased with the increasing Mn nutrition. Since the colour of fruits was correlated with the change in carotenoid content, the decrease in lycopene content promoted the reduction of redness and increase of yellowness of fruits. However, total polyphenol content and antioxidant activity significantly increased when plant were exposed to toxic levels of Mn. Observed changes could be the result of the oxidative stress induced by high concentrations of Mn. Polyphenolic compounds play a crucial role in the plant’s response to Mn stress and affect predominantly the total antioxidant properties of fruits, which could be used as a source of phenolics. Moreover, total phenolic content measurement, as an easy and inexpensive method, could be used as an indicator of Mn-induced stress in fruits of tomato.     

In vitro evaluation of the antioxidant activities in fruit extracts from citron and blood orange

Consumers are increasingly aware of diet related health problems and therefore demanding natural ingredients which are expected to be safe and health-promoting. Recently, number of studies on health benefits associated with citrus phytochemicals have been demonstrated. In the present study, an attempt has been made to isolate antioxidant fractions from two different citrus species such as Citron (Citrus medica) and blood orange (C. sinensis). Antioxidant fractions were extracted from mature, ripe fruits using five different solvents using a Soxhlet extractor. The total phenolic content of the extracts was determined by Folin–Ciocalteu method. MeOH:water (80:20) extract of citron and acetone extract of blood orange was found to contain maximum phenolics. The dried fractions were screened for their antioxidant activity potential using in vitro model systems such as 1, 1-diphenyl-2-picryl hydrazyl (DPPH), phosphomolybdenum method and as well as by the nitroblue tetrazolium (NBT) reduction test at different concentrations. The MeOH:water (80:20) fraction of citron showed highest radical scavenging activity 42.5%, 77.8% and 92.1% at 250, 500 and 1000 ppm, respectively, while MeOH:water (80:20) fraction of blood orange showed lowest DPPH radical scavenging activity at all the tested concentrations. Furthermore, all the fractions showed remarkable antioxidant capacity by the formation of phosphomolybdenum complex. In addition, superoxide radical scavenging activity was assayed using non-enzymatic (NADH/phenaxine methosulfate) superoxide generating system. All the extracts showed variable radical scavenging activity. The data obtained in the in vitro models clearly establish the antioxidant potency of citrus fruit extracts. However, comprehensive studies need to be conducted to ascertain the in vivo safety of such extracts in experimental animal models. To the best of our knowledge, this is the first report on antioxidant activity of citron and blood orange varieties of citrus fruits.     

Valorization of wild strawberry-tree fruits (Arbutus unedo L.) through nutritional assessment and natural production data

Arbutus wild berries have been traditionally collected and appreciated in the Mediterranean region, although it is actually considered an underutilized fruit-tree species. Increasing the scarce knowledge about its nutritional composition and natural production may interest a broad range of scholars, such as ethnobotanists, chemists, nutritionists and anthropologists. The present study aims to provide original data on the nutritional value and the biomass production of wild strawberry-tree fruits, studying the variation of these characteristics in fruits harvested in different years, from two different Spanish areas.Macro and micronutrient composition of mature Arbutus unedo fruits have been analyzed, with particular attention to the content of some bioactive compounds (fiber, vitamin C as ascorbic and dehydroascorbic acids, total phenolics, carotenoids, including lycopene) and the organic acids profile. The contribution to recommended dietary allowances (RDAs) of this exotic fruit has also been calculated. Fruit crop volume per tree has been estimated as well in the wild strawberry-tree populations surveyed to provide a general framework for discussing the agronomic potential of the species.A wide variability in the nutrient composition of strawberry-tree fruits was found which shows that the analysis of many different samples from different origins and seasons are required to provide average reliable data about the chemical composition of wild fruits. From the results obtained, strawberry-tree fruits can be considered a very good source of health promoting compounds as vitamin C and dietary fiber (202.6 mg/100 g and 42.6% minimum contribution to RDAs, respectively). They are also rich in total available carbohydrates, sugars, potassium and secondary metabolites, such as phenolic compounds, being poor in lipids and Na. These results, together with its high production may help to reinforce its consumption, as an alternative to the fruits available in the market or a source of bioactive compounds for dietary supplements or functional foods.     

Estimating volume and mass of citrus fruits by image processing technique

An image processing based technique was developed to measure volume and mass of citrus fruits such as lemons, limes, oranges, and tangerines. The technique uses two cameras to give perpendicular views of the fruit. An efficient algorithm was designed and implemented in Visual Basic (VB) language. The product volume was calculated by dividing the fruit image into a number of elementary elliptical frustums. The volume is calculated as the sum of the volumes of individual frustums using VB. The volumes computed showed good agreement with the actual volumes determined by water displacement method. The coefficient of determination (R²) for lemon, lime, orange, and tangerine were 0.962, 0.970, 0.985, and 0.959, respectively. The Bland–Altman 95% limits of agreement for comparison of volumes with the two methods were (−1.62; 1.74), (−7.20; 7.57), (−6.54; 6.84), and (−4.83; 6.15), respectively. The results indicated citrus fruit’s size has no effect on the accuracy of computed volume. The characterization results for various citrus fruits showed that the volume and mass are highly correlated. Hence, a simple procedure based on computed volume of assumed ellipsoidal shape was also proposed for estimating mass of citrus fruits. This information can be used to design and develop sizing systems.     

Fruit load or fruit position alters response to temperature and subsequently cherry tomato quality

Changes in fruit–source ratio during the growth and maturation of cherry tomato fruits were studied in combination with increased fruit temperature. Six treatments were compared: the presence or absence of local heating combined with different fruit origins (7P, fruit from trusses pruned to seven flowers; 14P, proximal fruits; 14D, distal fruits from trusses pruned to 14 flowers). 7P were less sensitive to heating whereas 14P and 14D showed greater reduction in water and dry matter (DM) content. Distal fruits had the lowest structural DM (sDM), which could be due to a lower fruit cell number. Heating further decreased the sDM, so that fruit sink size was the lowest for distal fruits subjected to heating. Under low competition (7P), heating had a beneficial effect on sugar and lycopene content, whereas acids, β‐carotene and vitamin C content were reduced. Under high competition (14P, 14D), heating increased the ratio sDM–DM. This was mainly due to the reduced content of sugars and acids, but also to the reduced accumulation of secondary metabolites such as vitamin C, β‐carotene and lycopene. This study underlines the interactions between fruit temperature and the fruit–source ratio and the consequences for fruit composition and nutritional quality. Copyright © 2005 Society of Chemical Industry     

Comparison of phytochemical profiles,cellular antioxidant and anti-proliferative activities in five varieties of wampee (Clausena lansium) fruits

Wampee (Clausena lansium) fruit is a seasonal food containing high levels of bioactive phytochemicals which may be useful for health benefits. This study compared the phytochemical composition, total and cellular antioxidant activities (CAA) as well as anti-proliferative activities of five different varieties of wampee fruits. The results showed that six phytochemical compounds (vanillic acid, ferulic acid, rutin, syringin, catechin and hesperetin) were found in wampee fruits. Total antioxidant activities varied dramatically in these five varieties when measured with oxygen radical absorbance capacity assay and peroxyl radical scavenging capacity assay. The results also showed that wampee fruit extracts varied enormously in their CAA and exhibited significant anti-proliferative activities against HepG2 human liver cancer cells. These results suggest the potential of wampee fruits as functional foods and industrial application of wampee fruit in the future.     

Polyphenol composition, vitamin C content and antioxidant capacity of Mauritian citrus fruit pulps

The pulp extracts of twenty-one varieties of citrus fruits (oranges, satsumah, clementine, mandarins, tangor, bergamot, lemon, tangelos, kumquat, calamondin and pamplemousses), commonly grown in Mauritius, were characterised in terms of their total soluble solids (TSS), titratable acidity (TA), polyphenol composition and vitamin C contents. Total phenolics ranged from 406.3 ± 14 to 1694 ± 19 ??g g^− 1 fresh weight (FW). Total flavonoids varied between 133 ± 6 and 965 ± 7 ??g g^− 1 FW and vitamin C contents were from 166 ± 19 ??g/mL to 677 ± 22 ??g/mL. The pulp of a pamplemousse variety had the highest TSS/TA ratio whereas lemon pulps had lowest TSS/TA ratios. The antioxidant activities of the pulp extracts were assessed and total phenolics correlated strongly with the trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant capacity (FRAP) and hypochlorous acid (HOCl) scavenging activity assays. Based on their antioxidant activities, nine citrus fruits namely, one orange, tangor, kumquat, calamondin and pamplemousse variety and two mandarin and tangelo varieties were further characterised for their flavanone, flavonol and flavone levels by HPLC. Hesperidin (6.89 ± 0.06 to 26.98 ± 0.07 mg/g FW) and narirutin (0.27 ± 0.01 and 20.91 ± 0.10 mg/g FW) were present at high concentrations compared to the other flavonoid glycosides in the pulp extracts. Naringin was detected only in pulp extracts of pamplemousses. In the light of the data obtained, citrus fruit pulps represent an important source of phytochemicals with potent antioxidant capacity.     

Rapid Residue Determination of Cyenopyrafen in Citrus Peel,Pulp, and Whole Fruit Using Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry

A sample pretreatment method was established to analyze the residues of cyenopyrafen in citrus peel, pulp, and whole fruit using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The target compound was extracted from all matrices with acetonitrile and then cleaned by dispersive solid phase extraction using 10 mg GCB?+?150 mg MgSO₄ for citrus peel; 50 mg PSA?+?150 mg MgSO₄ for citrus pulp, and 50 mg C18?+?50 mg PSA?+?150 mg MgSO₄ for whole fruits. Determination of the target compound was achieved in less than 5.0 min using an electrospray ionization source in positive mode. Average recoveries in citrus peel, pulp, and whole fruit spiked at 0.01, 0.2, and 2 mg kg^?1 ranged from 84.9 to 105.1%, with relative standard deviations (RSD_r) of 0.7–7.9%. The reproducibility (RSD_R) ranged from 2.6 to 6.8%. The limits of detection and quantification ranged from 0.00032 to 0.0012 mg kg^?1 and from 0.0009 to 0.0036 mg kg^?1, respectively. This method was used to determine cyenopyrafen residues in citrus fruits to study its dissipation under field conditions. The trial results showed that the half-lives of cyenopyrafen in whole fruits were 10.2 and 6.2 days in Hunan and Guangxi provinces, respectively. The developed analytical method provides a basis to establish maximum residue limits and monitor cyenopyrafen residue in citrus.     

Survey of o-phenylphenol residues found in marketable citrus fruit

Residues of o-phenylphenol (OPP) were determined in peel, pulp and the whole fruit of Shamouti and Valencia oranges, grapefruits and lemons which were treated under industrial conditions with solutions of sodium-o-phenylphenate (SOPP). The OPP residues found in the peel of the different species of citrus fruit varied from 5.4 to 26.1 ppm OPP. In many cases OPP residues were not detectable in the pulp, and in other cases traces and 0.4 ppm of OPP were found. The residues in the whole fruit were found to range from 1.8 to 8.3 ppm, with 80% of the samples analysed containing less than 5 ppm. These amounts were within the tolerance limits generally established for residues of OPP in citrus fruit (10 and 12 ppm of OPP). The SOPP concentration of the disinfectant solutions ranged from 0.24 to 0.55% SOPP.4H₂O and had little effect on the OPP content of the fruits. The fruits which were treated at a pH below 11.6 usually contained more OPP than those treated at pH values between 11.6 and 12.3.