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A simple and rapid method using high performance liquid chromatography (HPLC) was developed to determine levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in litchi fruit pericarp tissue. This HPLC method used acetonitrile gradient elution and shortened the time required for determinations of adenosine phosphates. This analysis exhibited good repeatability (coefficients of variation 1.28–1.80 %) and recovery rate (94.7–97.1 %). The correlation coefficients of ATP, ADP and AMP with their peak areas at a range of 0–80 ng were 0.9946, 0.9994 and 0.9974, respectively. This method was applied to determine levels of adenosine phosphates in pericarp tissue of litchi fruit at harvest. There were 27.4 μg/g of ATP, 35.4 μg/g of ADP and 7.9 μg/g of AMP on a fresh mass basis.

Controlled enzymatic modification proteins are currently being used as good sources of bioactive protein ingredients, and hydrolysates derived from bighead carp muscles may serve as antioxidants through the control of the processing-related parameters. The antioxidant ability was evaluated with regard to the scavenging effect on free radical DPPH·, OH· and O2 ·–. Due to the robustness, fault tolerance, high computational speed and self--learning ability, artificial neural network (ANN) can be employed to build a predictive model for hydrolysis and optimize the hydrolysis variables: pH, temperature, hydrolysis time, muscle/water ratio and enzyme/substrate ratio (E/S) for the production of antioxidant peptides. Optimum conditions to achieve the maximum antioxidant ability were obtained. The hydrolysates, which scavenged most effectively the DPPH·, OH· and O2 ·–, were hydrolyzed for 4.8 h with an activity of alcalase of 4.8 AU/kg, for 6 h with 3.84 AU/kg and for 4.3 h with 4.8 AU/kg, at pH=7.5 and 60 °C. Their respective muscle/water ratio was 1:1.9, 1:1.4 and 1:1. The present study confirmed that ANN could be used to simulate the hydrolysis process and predict hydrolysis conditions under which the hydrolysates could show the most effective scavenging ability on DPPH·, OH· and O2 ·–.

Caffeine, total amino acids, water extract and moisture content are considered to be quality indicators for leaf teas and teabags. These analyses were examined in 20 leaf teas and 36 teabags sampled from Australian supermarkets. About 70% of the analysed samples showed a moisture content higher than Vie maximum accepted level, 6.5%, for tea storage and marketing by the tea industries and traders. Water appropriate extract of 15 samples out of 36 teabags was lower than that of the teas without teabags, which indicates that the quality of the paper used for teabags needs to be evaluated. Moreover, one of the black leaf tea samples was found to have a water extract below the lower limit of international standards. Four green and black teas of the same brand, claimed to contain less than 3% caffeine, were found to have 3-4%, the same as the other samples analysed in this study. The mean total contents of amino acids were 2.50% and 1.76% in black leaf teas and the teabags, respectively, whereas they were 3.44% and 2.28% in green leaf teas and the teabags, respectively. Furthermore, the weights of 28 teabags out of 36 samples were found to lie outside of the proposed +/- 2% variation accepted by the tea industries and traders, and 4 samples showed even larger variation, 10% being out of the proposed weights. This investigation also showed that the solubility of caffeine and water extract was affected by the permeability of teabags, whereas total amino acids were very variable. These results suggest that an efficient and practical quality control system for both imported and Australian-made teas in the Australian supermarkets should be developed, implemented and enforced. Chemical analysis should be a part of the system for establishing an objective assessment for the quality control. (c) 2004 Elsevier Ltd. All rights reserved.

Ubrani plodovi šljive sapodilo izloženi su inhibitoru djelovanja etena 1- metilciklopropenu (1-MCP), volumne koncentracije od 0, 40 ili 80 nL/L, tijekom 24 h pri 20 °C. Voće je zatim skladišteno na 20 °C i 85-95 % relativne vlažnosti, pa su zatim procijenjeni njegova kakvoća i karakteristike zrenja. Obrada 1-metilcikloproprenom odgodila je maksimalnu respiraciju, proizvodnju etena i poligalakturonaze za 6 dana. Također je odgodila smanjenje koncentracije vitamina C, titracijske kiselosti i udjela klorofila do kojeg dolazi zrenjem voća. U usporedbi s netretiranim voćem usporena je i promjena udjela čvrste tvari. Primjena 1-metilciklopropena djelotvorna je tehnologija inhibicije zrenja i očuvanja kakvoće ubrane šljive sapodilo., Sapodilla fruits were exposed to the ethylene action inhibitor 1-methylcyclopropene (1-MCP) at 0, 40 or 80 nL/L for 24 h at 20 °C. Fruits were then stored at 20 °C and 85−95 % relative humidity and later assessed for quality and ripening characteristics. 1-MCP treatments delayed the increases in the rates of respiration and ethylene production by 6 days. Treatments also delayed by 6 days the increase in polygalacturonase activity. Decreases in ascorbic acid, titratable acidity and chlorophyll content that are normally seen with ripening were delayed. Changes in the content of soluble solids were also slowed compared to untreated fruit. The application of 1-MCP was an effective technology for ripening inhibition and quality maintenance of harvested sapodilla fruit.

Postharvest pericarp browning of litchi fruit results in an accelerated loss in shelf life and a reduced commercial value. Visual quality was lost in only 6 h at ambient temperature when fruit were removed from storage at 2 °C, due to browning. The experiment was conducted to test the role of chitosan coating in inhibiting skin browning and extending shelf life of cold-stored litchi fruit at ambient temperature. Litchi fruit were treated with 2 g chitosan/100 g solution and then stored for 20 days at 2 °C and 90–95% relative humidity (RH), prior to shelf life evaluation at 25 °C and 80–90% RH. Changes in polyphenol oxidase (PPO) activity, anthocyanin concentration, colour index, eating quality and concentrations of total soluble solids and titratable acidity were measured. The effects of chitosan coating on disease incidence were also evaluated. Application of chitosan coating delayed the decrease in anthocyanin content, the increase in PPO activity and the changes in colour index and eating quality, reduced the decrease in concentrations of total soluble solids and titratable acidity, and partially inhibited decay. The results suggested that treatment with chitosan coating exhibited a potential for shelf life extension at ambient temperature when litchi fruit were removed from cold storage.

Lycopene belongs to the carotenoid family, which has more than 700 members. In human serum, only 14 caroteinoids have been identified, and, among these, lycopene was the most abundant. Lycopene is regarded as one of the most efficient singlet oxygen quencher and peroxyl radical scavenger of all the carotenoids and may represent an important defense mechanism in the human body. Singlet oxygen and free radicals can cause biological damage to important macromolecules and membrane constituents, and the presence of natural antioxidants may help to control these degradative reactions.The oxidation of low density lipoproteins (LDL) has been implicated in the development of atherosclerosis which makes the antioxidants that protect LDL potential antiatherogenic agents. There is growing evidence that certain combinations of natural antioxidants have synergistic antioxidant activity, that is, the actual inhibitory activity of the mixture is greater than the additive activities of the individual antioxidants. Lycopen...

Postharvest browning of litchi fruit pericarp is a major problem, resulting in accelerated shelf life and reduced commercial value of the fruit. The browning was generally thought to be a rapid degradation of red pigments caused by polyphenol oxidase (PPO) and peroxidase (POD). This work is conducted to understand the role of POD in anthocyanin degradation in litchi pericarp, which is less understood than PPO. POD activity in the pericarp increased consistently with skin browning index during storage of litchi fruit, but was negatively associated with anthocyanin concentration. Although POD cannot directly oxidize litchi anthocyanin in the presence of H 2 O 2 in vitro, the anthocyanin content decreased rapidly after the addition of guaiacol solution, which indicated that the anthocyanin degradation by POD exhibited a coupled oxidation mechanism. Furthermore, anthocyanidin, produced by hydrolysis of the purified anthocyanin, could act as a substrate of POD. Thus, enzymatic browning of litchi fruit pericarp caused by POD may involve an anthocyanase–anthocyanin–phenolic–H 2 O 2 reaction.

Carotenoids have drawn considerable interest, due to their role in preventing cardiovascular disease. In a large prospective study of female nurses, a 26% and 20% lower risk of coronary artery dise...

Polyphenolic substances or polyphenols include many classes of compounds ranging from phenolic acids, colored anthocyanins, simple flavonoids, and complex flavonoids. Polyphenolics contribute to the bitterness and astringency of fruits and fruit juices due to the interaction between polyphenolics, mainly procyanidins, and the glycoproteins in saliva. Polyphenols contribute largely to cellular processes within the body. In terms of pharmacological activity, they act against the oxidation of high-density lipoproteins (HDLs). Hence, they help the body retain important HDL while helping it get rid of problematic low-density lipoproteins (LDLs). In addition, polyphenols have also been found to have antiulcer, anticarcinogenic, and antimutagenic activities. The reason behind these activities is polyphenol's strong antioxidant power because they are able to quench free radicals. Green tea and grape seed extracts provide a superior source of monomers that are relatively inexpensive to extract. Comparatively, pine...

Litchi (Litchi chinensis Sonn.) is a subtropical to tropical fruit of high commercial value in international trade. However, harvested litchi fruit rapidly lose their bright red skin colour. Peel browning of harvested litchi fruit has largely been attributed to rapid degradation of red anthocyanin pigments. This process is associated with enzymatic oxidation of phenolics by polyphenol oxidase (PPO) and/or peroxidase (POD). PRO and POD from litchi pericarp cannot directly oxidize anthocyanins. Moreover, PPO substrates in the pericarp are not well characterised. Consequently, the roles of PPO and POD in litchi browning require further investigation. Recently, an anthocyanase catalysing the hydrolysis of sugar moieties from anthocyanin to anthocyanidin has been identified in litchi peel for the first time. Thus, litchi enzymatic browning may involve an anthocyanase-anthocyanin-phenolic-PPO reaction. Current research focus is on characterising the properties of the anthocyanase involved in anthocyanin degradation. Associated emphasis is on maintenance of membrane functions in relation to loss of compartmentation between litchi peel oxidase enzymes and their substrates. (C) 2004 Elsevier Ltd. All rights reserved.

Litchi pulp is very perishable and thus has a short shelf life, with marketers and consumers alike desiring a longer period. The current study was conducted to investigate the effects of chitosan coating on quality maintenance and shelf life extension of peeled fruit of cv. Huaizhi. Manually peeled litchi fruits were treated with aqueous solutions of 0%, 1%, 2% or 3% of chitosan, placed into trays over-wrapped with plastic film, and then stored at −1 °C. Changes in sensory quality in terms of taste and colour scales and weight loss were evaluated. Polyphenol oxidase (PPO) and peroxidase (POD) activities were also measured. Application of chitosan coating retarded weight loss and the decline in sensory quality, with higher contents of total soluble solids, titratable acid, and ascorbic acid, and suppressed the increase in activities of PPO and POD. The results showed that application of chitosan coating effectively maintained quality attributes and extended shelf life of the peeled fruit.

Experiments were conducted to test the effect of pure oxygen treatment on energy charge of peel tissue which may affect membrane integrity during browning of litchi fruit after harvest. Fruit were kept in air or pure O 2 for up to 6 days at 25 °C. Changes in browning index, membrane permeability, contents of ATP, ADP and AMP and energy charge were measured. As fruit browned, membrane permeability increased gradually, while ATP content and energy charge decreased rapidly. Exposure to pure O 2 significantly prevented peel browning, maintained high levels of ATP, ADP and energy charge, and reduced increase in membrane permeability of peel tissue of litchi fruit after 4 days of storage. The inhibition of browning of litchi fruit peel suggested that high levels of ATP, ADP and energy charge of litchi fruit kept in pure O 2 may contribute to maintenance of membrane integrity which reduced decompartmentation of enzymes and substrates resulting in enzymatic browning.

Polyphenol oxidase (PPO) from fresh-cut Chinese water chestnut (CWC) was extracted and the effect of citric acid on the PPO activity assayed. Citric acid at low concentrations stimulated PPO activity, but at 0.1 M or higher markedly inhibited the activity. On the basis of the inhibition of PPO activity in vitro, the use of 0.1 M citric acid for shelf life extension and quality maintenance of fresh-cut CWC was investigated. Fresh-cut CWC were dipped in a solution of 0.1 M citric acid, placed in trays over-wrapped by plastic films, and then stored at 4 °C. Changes in surface discoloration, eating quality and disease incidence were evaluated. Treatment with 0.1 M citric acid markedly extended the shelf life, inhibited surface coloration and disease development, and reduced the loss in eating quality associated with the contents of ascorbic acid and total soluble solid, titratable acidity and ascorbic acid. It is suggested that application of citric acid better maintained quality and extended shelf life of fresh-cut CWC.

Litchi fruit can be stored at −18 °C without obvious adverse effects on the aril, but the pericarp darkens and browns when they are frozen or thawed. Experiments were conducted to test effects of hydrochloric acid on browning inhibition of litchi fruit pericarp for displacement of sulphur application. Litchi fruit were soaked in 0.5%, 1% and 2% HCl for 2–10 min. Fruit appearance and membrane leakage were assessed after 1 day of storage under ambient conditions of 25 °C and 80–90% relative humidity. In terms of browning control of and fruit pericarp damage, treatment with 1% HCl for 6 min gave the best red colour and minimal damage. 1% HCl treatment markedly inhibited polyphenol oxidase activity and maintained high anthocyanin content in litchi fruit pericarp tissue. Fruit treated with 1% HCl and stored at −18 °C for 12 months had a shelf life of 12 h at ambient temperature, with a uniform red colour and acceptable quality. Use of 1% HCl could be considered for commercial application in extending shelf life and maintaining quality of frozen litchi fruit following storage and during marketing.

Seven phenolic acids related to the botanical origins of nine monofloral Eucalyptus honeys from Australia, along with two abscisic isomers, have been analyzed. The mean content of total phenolic acids ranges from 2.14 mg/100 g honey of black box (Eucalyptus largiflorens) honey to 10.3 mg/100 g honey of bloodwood (Eucalyptus intermedia) honey, confirming an early finding that species-specific differences of phytochemical compositions occur quantitatively among these Eucalyptus honeys. A common profile of phenolic acids, comprising gallic, chlorogenic, coumaric and caffeic acids, can be found in all the Eucalyptus honeys, which could be floral markers for Australian Eucalyptus honeys. Thus, the analysis of phenolic acids could also be used as an objective method for the authentication of botanical origin of Eucalyptus honeys. Moreover, all the honey samples analyzed in this study contain gallic acid as the main phenolic acid, except for stringybox (Eucalyptus globoidia) honey which has ellagic acid as the main phenolic acid. This result indicates that the species-specific differences can also be found in the honey profiles of phenolic acids. Further-more, the analysis of abscisic acid in honey shows that the content of abscisic acid varies from 0.55 mg/100 g honey of black box honey to 4.68 mg/ 100 g honey of bloodwood honey, corresponding to the contents of phenolic acids measured in these honeys. These results have further revealed that the HPLC analysis of honey phytochemical constituents could be used individually and/or jointly for the authentication of the botanical origins of Australian Eucalyptus honeys. (C) 2003 Elsevier Ltd. All rights reserved.

Banana fruit are highly susceptible to chilling injury during low temperature storage. Experiments were conducted to compare ethylene binding during storage at chilling (3 and 8 degreesC) versus optimum (13 degreesC) temperatures. The skins of fruit stored at 3 and 8 degreesC gradually darkened as storage duration increased. This chilling effect was reflected in increasing membrane permeability as shown by increased relative electrolyte leakage from skin tissue. In contrast, banana fruit stored for 8 days at 13 degreesC showed no chilling injury symptoms. Exposure of banana fruit to the ethylene binding inhibitor 1-methylcyclopropene (1 mul l(-1) 1-MCP) prevented ripening. However, this treatment also enhanced the chilling injury accelerated the occurrence of chilling injury-associated increased membrane permeability. C-14-ethylene release assay showed that ethylene binding by banana fruit stored at low temperature decreased with reduced storage temperature and/or prolonged storage time. Fruit exposed to 1-MCP for 12 h and then stored at 3 or 8 degreesC exhibited lower ethylene binding than those stored at 13 degreesC. Thus, chilling injury of banana fruit stored at low temperature is associated with a decrease in ethylene binding. The ability of tissue to respond to ethylene is evidently reduced, thereby resulting in failure to ripen.

Demand for bean products is growing because of the presence of several health-promoting components in edible bean products such as saponins. Saponins are naturally occurring compounds that are widely distributed in all cells of legume plants. Saponins, which derive their name from their ability to form stable, soaplike foams in aqueous solutions, constitute a complex and chemically diverse group of compounds. In chemical terms, saponins contain a carbohydrate moiety attached to a triterpenoid or steroids. Saponins are attracting considerable interest as a result of their diverse properties, both deleterious and beneficial. Clinical studies have suggested that these health-promoting components, saponins, affect the immune system in ways that help to protect the human body against cancers, and also lower cholesterol levels. Saponins decrease blood lipids, lower cancer risks, and lower blood glucose response. A high saponin diet can be used in the inhibition of dental caries and platelet aggregation, in the treatment of hypercalciuria in humans, and as an antidote against acute lead poisoning. In epidemiological studies, saponins have been shown to have an inverse relationship with the incidence of renal stones. Thermal processing such as canning is the typical method to process beans. This study reviews the effect of thermal processing on the characteristics and stability of saponins in canned bean products. Saponins are thermal sensitive. During soaking and blanching, portions of saponins are dissolved in water and lost in the soaking, washing, and blanching liquors. An optimum thermal process can increase the stability and maintain the saponins in canned bean products, which is useful for assisting the food industry to improve thermal processing technology and enhance bean product quality.

Litchi fruit peel anthocyanins were extracted with 0.5 M HCl, and then purified by an Amberlite XAD-7 column and Sephadex LH-20 column chromatography. The major part of the anthocyanins of litchi pericarp, which (94.3% of total), was obtained. Furthermore, the partially purified anthocyanin was identified as cyanindin-3-rutinoside, with a molecular weight of 595, using HPLC equipped with mass spectrometry. The results corroborate the previous observation of Zhang, Pang, Ji, and Jiang (2001 Food Chemistry, 75, 217–221), who suggested that nonenzymatic degradation of anthocyanins could participate in postharvest browning of litchi pericarp.

Tomatoes and tomato products are the major source of lycopene in the diet. The bioavailability of lycopene is different in raw tomatoes compared to processed tomato products. This is due to the chemical and physical properties of the different lycopene isomers. All-trans-lycopene is found in raw tomatoes and is a poor bioavailable source, whereas, processed tomato products are more bioavailable because they contain more cis-isomers. Heat and mechanical processing of tomatoes induces rupture of the cell walls, thereby releasing lycopene from its food matrix. Heat processing also induces cis-trans isomerization and disrupts protein-carotenoid complexes. Many dietary components also impact lycopene bioavailability, like the amount and type of fat present with the intake and processing of tomato products, the amount and type of fiber present, and the interaction between carotenoids. Fundamentally, anything that enhances formation and incorporation of lycopene in bile acid micelles increases bioavailability, and the opposite is true in that anything that interferes with micelle formation decreases bioavailability.

Summary A heat treatment to inhibit browning and maintain the quality of fresh-cut Chinese water chestnut was developed. Slices of Chinese water chestnut, cv. Guilin, were immersed in boiling water for 30 s, placed into film-wrapped trays and then stored at 4 °C for up to 12 days. Changes in browning, eating quality and disease incidence were measured. The effect of heat treatment on the content of total phenolics and activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) was also evaluated. The heat treatment effectively prevented browning associated with PAL, PPO and POD activities and total phenolic content and delayed the decrease in eating quality, which is associated with reduced total soluble solids, titratable acidity and ascorbic acid, compared with fresh-cut Chinese water chestnut. Inhibition of browning by heat treatment without microbial growth was achieved for 12 days of storage at 4 °C. These results showed that heat treatment effectively maintained the quality of fresh-cut Chinese water chestnut.

As part of a 4-year project to study phenolic compounds in tea shoots over the growing seasons and during black tea processing in Australia, an HPLC method was developed and optimised for the identification and quantification of phenolic compounds, mainly flavanols and phenolic acids, in fresh tea shoots. Methanol proved to be the most suitable solvent for extracting the phenolic compounds, compared with chloroform, ethyl acetate and water. Immediate analysis, by HPLC, of the methanol extract showed higher separation efficiency than analyses after being dried and redissolved. This method exhibited good repeatability (CV 3-9%) and recovery rate (88-116%). Epigallocatechin gallate alone constituted up to 115 mg/g, on a dry basis, in the single sample of Australian fresh tea shoots examined. Four catechins (catechin, gallocatechin, epicatechin and epigallocatechin) and six catechin gallates (epigallocatechin gallate, catechin gallate, epicatechin gallate, gallocatechin gallate, epicatechin digallate and epigallocatechin digallate) have been identified and quantified by this HPLC method. In addition, two major tea alkaloids, caffeine and theobromine, have been quantified, while five flavonol glycosides and six phenolic acids, including quinic acids and esters, were identified and quantified. (C) 2003 Elsevier Ltd. All rights reserved.

SummaryPericarp browning and decline in fruit quality are major problems of harvested litchi fruit. The effects of a pure O2 atmosphere on enzymatic browning and quality of harvested litchi fruit were investigated. Litchi fruit were kept in air or pure O2 for 6 d at 28°C. Changes in browning, polyphenol oxidase (PPO), anthocyanase, total soluble solids, titratable acidity and ascorbic acid were monitored. Effects of pure O2 on in vitro activities of PPO and anthocyanase were also evaluated. Exposure of litchi fruit to pure O2 significantly (P≤0.05) reduced skin browning during storage. Pure O2 inhibited the activities of PPO and anthocyanase which may account for browning inhibition. Furthermore, pure O2-treatment inhibited the in vitro activities of PPO and anthocyanase during incubation for 4 h. Litchi fruit exposed to pure O2 for 6 d had higher total soluble solids and titratable acidity than those kept in air, but lower ascorbic acid. Thus, application of pure O2 effectively reduced skin browning and ...

Flavonoids of nine Australian monofloral Eucalyptus honeys have been analyzed and related to their botanical origins. The mean content of total flavonoids varied from 1.90 mg/100 g of honey for stringybark (E. globoidia) honey to 8.15 mg/100 g of honey for narrow-leaved ironbark (E. crebra) honey, suggesting that species-specific differences occur quantitatively among these Eucalyptus honeys. All of the honey samples analyzed in this study have a common flavonoid profile comprising tricetin (5,7,3',4',5'-pentahydroxyflavone), quercetin (3,5,7,3',4'-pentahydroxyflavone), and luteolin (5,7,3',4'-tetrahydroxyflavone), which, together with myricetin (3,5,7,3',4',5'-hexahydroxyflavone) and kaempferol (3,5,7,4'-tetrahydroxyflavone), were previously suggested as floral markers for European Eucalyptus honeys. Thus, flavonoid analysis could be used as an objective method for the authentication of the botanical origin of Eucalyptus honeys. Moreover, species-specific differences can also be found in the composition of honey flavonoid profiles. Among these honeys, bloodwood (E. intermedia) honey contains myricetin and tricetin as the main flavonoid compounds, whereas there is no myricetin detected in yapunyah (E. ochrophloia), narrow-leaved ironbark (E. crebra), and black box (E. largiflorens) honeys. Instead, these types of Eucalyptus honeys may contain tricetin, quercetin, and/or luteolin as their main flavonoid compounds. Compared to honeys from other geographical origins, the absence or minor presence of propolis-derived flavonoids such as pinobanksin, pinocembrin, and chrysin in Australian honeys is significant. In conclusion, these results demonstrate that a common flavonoid profile exists for all of the Eucalyptus honeys, regardless of their geographical origins; the individual species-specific floral types of Eucalyptus honey so common in Australia could be possibly differentiated by their flavonoid profile differences, either qualitatively or quantitatively or both.

Overripening of Chinese jujube (Zizyphus jujuba M) fruit at the postharvest stage usually results in a dramatic decline in quality. The role of 1-methylcyclopropene (1-MCP) and gibberellic acid (GA) in fruit ripening of Chinese jujube during storage in relation to quality was investigated. Fruit ripening of jujube was significantly enhanced by ethylene, whereas rates of respiration and ethylene production of the fruit were reduced by 1-MCP. Treatment with 1-MCP or GA delayed the decreases in firmness and vitamin C and reduced the level of ethanol. Furthermore, the effectiveness of 1-MCP was improved by replicate treatments during storage at 20 or 2 °C. In addition, treatment with GA + 1-MCP resulted in additive beneficial effects on ripening inhibition of the fruit. Copyright © 2003 Society of Chemical Industry

Exposure to high O2 concentrations may stimulate, have no effect or retard fruit ripening depending upon the commodity, O2 concentration and storage time among other variables. The ethylene-binding inhibitor 1-methylcyclopropene (1-MCP) was used to investigate ethylene-mediated softening responses of Williams banana fruit exposed to elevated O2 for various periods of time. Fruit softening was measured at 25 °C and 90% relative humidity. Exposure to high O2 concentrations for 5 days resulted in accelerated softening. Softening of fruit treated with 1-MCP for 12 h followed by 5 days of storage in high O2 atmospheres at 25 °C was enhanced with increasing O2 concentration between 21 and 100%. However, overall softening was much less compared to non-1-MCP-treated fruit. Softening of 1-MCP-treated fruit was progressively enhanced with increasing holding time from 5 to 20 days. Fruit treated with 1-MCP and then held for 10 days in high O2 atmospheres followed by exposure to ethylene for 24 h and subsequent storage for 5 days at 25 °C softened more rapidly than those held in air for 10 days. 1-MCP-treated fruit held in various high O2 atmospheres can regain gradually the sensitivity to ethylene and finally ripen over time. Enhanced softening of fruit exposed to elevated O2 concentrations suggests that high O2 treatments enhance synthesis of new ethylene binding sites.

Application of chitosan coating to browning control and quality maintenance of fresh-cut Chinese water chestnut (CWC) was investigated. Fresh-cut CWC were treated with aqueous solution of 0.5, 1 or 2 g chitosan/100 mL, placed into trays over-wrapped with plastic films, and then stored at 4°C. Changes in color, total phenolic content and phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) activities were measured. The effects of chitosan coating on eating quality and overgrowth of spoilage organisms were also evaluated. Application of chitosan coating delayed discoloration associated with reduced activities of PAL, PPO and POD as well as lower total phenolic content, and slowed down the loss in eating quality associated with higher contents of total soluble solids, titrratable acidity and ascorbic acid of fresh-cut CWC. Disease development of the fresh-cut CWC-treated chitosan coating was also inhibited compared to the control. Increasing the concentration of chitosan coating markedly enhanced the beneficial effects. The results showed that application of chitosan coating effectively extended shelf life and maintained quality of fresh-cut CWC.

Effects of exogenously applied abscisic acid (ABA) on ethylene production rate, phenylalanine ammonia-lyase ( PAL) enzyme activity, and anthocyanin and phenolic concentrations in harvested strawberry cv. Everest fruit were evaluated. Colouration and firmness were also assessed on fruit held for 3 days at 20 degreesC. ABA treatment accelerated fruit colour and softening. Treatment with 10(-5) or 10(-4) mol ABA l(-1) stimulated ethylene production. Anthocyanin and phenolic contents and PAL activity increased during storage, but more rapidly in ABA treated fruit. As a result, red colour development was accelerated. Endogenous ABA may play a role in strawberry fruit colour development during ripening through up-regulation of ethylene production and PAL activity.

SummaryPostharvest pericarp browning of litchi fruit results in an accelerated loss in shelf life and reduced commercial value. Visual quality was lost in only 6.h at room temperature after fruit were removed from storage at 2°C, due to browning. Cultivar ‘Huaizhi’ fruit stored for 2 d at 8°C, for 26 d at 2°C, followed by 2 d storage at 15°C prior to a shelf-life evaluation at 23–258C, 80–90% r.h. were compared with continuous storage for 30 d at 2°C. Changes in polyphenol oxidase (PPO), anthocyanin, membrane leakage, colour, eating quality, total soluble solids, titratable acidity, and ascorbic acid were measured. The effects of temperature conditioning on disease incidence was also evaluated. Application of low-temperature acclimation delayed the decrease in anthocyanin content, the increases in PPO activity and membrane leakage, the changes in colour and eating quality, and partially inhibited decay of fruit. The results suggested that potential exists for shelf-life extension at ambient temperature wh...

The Occupational Medicine Forum is prepared by the ACOEM Occupational and Environmental Medical Practice Committee and does not necessarily represent an official ACOEM position. The Forum is intended for health professionals and is not intended to provide medical or legal advice, including illness prevention, diagnosis or treatment, or regulatory compliance. Such advice should be obtained directly from a physician and/or attorney.

The effect of the gene polymorphism for the key enzyme's folacin metabolism pathway on plasmatic homocysteine (Hcy) levels in fertile woman was observed.The subjects were from Shaoxing City, Jiangsu province in 2012, the selection criteria for the women of childbearing age were between 20-45 years old, with an average age of 28.2 (95%CI:27.8-28.6) years old. Sample collection continued uninterrupted lasted seven days, a total of 535 samples were collected, venous blood with EDTA addition or sodium citrate to anticoagulant. After separation, the blood cells and blood plasma were cryopreserved. DNA was extracted using spin column method. All the samples were selected for the gene polymorphism testing of the key enzyme's on folate metabolism and monitoring of plasmatic Hcy level.Eight single nucleotide polymorphism (SNP) sites of methylenetetrahydrofolate reductase gene (MTHFR) , methionine synthase gene (MS) , synthetic methionine reductase gene (MSR) and cystathionine β synthase gene (CBS) were detected. It was found the genotype AA of the SNP sites-rs1801131 would result higher plasmatic Hcy levels (8.99 µmol/L) than the genotypes CC (7.81 µmol/L) and CA(8.38 µmol/L) (P0.01) . Similarly, the genotype TT of the SNP sites-rs1801133 was significantly responded to the increasing of Hcy levels (11.10 µmol/L) than the genotype CC (8.15 µmol/L) and CT (8.45 µmol/L), (P0.01) . The two sites of genotype combination of AA-TT could also result in the significant increase of Hcy levels (11.02 µmol/L) than other combined genotypes (genotypes CC-CC, CA-CC, CA-CT, AA-CC, AA-CT), especially the genotype CC-CC. And the risk factor was 1.41 (95CI:1.20-1.66) times over the genotype CC-CC.The gene mutations of two SNP sites rs1801131 and rs1801133 in MTHFR would increase Hcy levels.

The mature longan fruit (Diniocarpus longan Lour.) is small (ca. 1.5-2 cm diameter), conical, heart-shaped or spherical in shape and light brown in colour. It has a thin, leathery and indehiscent pericarp surrounding a succulent, edible white aril. The aril contains a relatively large dark brown seed. Maturity can be determined on the basis of fruit weight, skin colour, flesh sugar concentration, flesh acid concentration, sugar:acid ratio, flavour and/or days from anthesis. Longan fruit are non-climacteric with little change in soluble solids concentration (SSC) or titratable acidity (TA) after harvest. Longan fruit deteriorate rapidly unless proper handling techniques are employed. The major factors reducing the storage life and marketability of longan fruit are microbial decay and pericarp browning. Low temperature storage at 1-5 degreesC is used to reduce pathological decay, but has a only limited role in reducing pericarp browning. Moreover, the, fruit deteriorate rapidly when removed from cold storage. Under refrigeration, longan fruit have a storage life of approximately 30 days. Pulp quality and disease development are generally stable during cold storage until such time as fruit become visually unacceptable from pericarp browning. Sulfur dioxide fumigation has been the most effective postharvest treatment for control of pericarp browning in longan fruit, and is used extensively in commercial situations at present. However, there is increasing consumer and regulatory resistance to the use of this chemical. Insect disinfestation has become increasingly important with the expanding export market. Irradiation and heat treatments for insect disinfestation of longan fruit have been found to be alternatives to treatment with insecticides. Recent research has focused on reducing these major postharvest problems in order to produce light-coloured, chemical-free fruit without disease or insect infestation. (C) 2002 Elsevier Science B.V. All rights reserved.

Elevated temperatures experienced by harvested fruit can modulate theirripening. Moreover, heat treatments can be applied to reduce susceptibility tolow temperature disorders and to help control pests and diseases. Theethylene-binding inhibitor 1-methylcyclopropene (1-MCP) was used to investigatethe ethylene-mediated softening response of banana fruit exposed to elevatedtemperatures. A preliminary experiment was conducted to determine levels ofhightemperature (30–50 °C) imposed for a short periodof time that did not cause skin scald. The softening response of Williamsbananafruit treated with 1-MCP at various temperatures and durations wascharacterisedin subsequent experiments. Exposure of fruit to hot air for 60 minat 45 °C or for 30 min at50 °Ccaused 30–40% peel scald. The peel was not visibly damaged forfruit treated at 40 °C for up to 60 min.Softening of fruit treated with 1-MCP for 12 h at25 °Cand then held for 7 days at 30, 35 or 40 °C wasinhibited in proportion to increasing concentration over the range 0.01–1μl/l 1-MCP. However, softening was progressively enhanced withincreasing holding temperatures from 30–40 °Cand/or time from 1–7 days, although fruit treated with the higher 1-MCPconcentrations of 1 and 10 μl/l were comparatively lessresponsive to heat. Although banana fruit held at30–40 °Cdid not de-green, their increased softening at elevated temperatures andinhibition of this response by 1-MCP suggest that heat enhances synthesis ofnewethylene sites which mediated banana fruit softening.

Excessive manganese (Mn) exposure is not only a health risk for occupational workers, but also for the general population. Sodium para-aminosalicylic acid (PAS-Na) has been successfully used in the treatment of manganism, but the involved molecular mechanisms have yet to be determined. The present study aimed to investigate the effects of PAS-Na on sub-chronic Mn exposure-induced impairments of spatial learning and memory, and determine the possible involvements of γ-aminobutyric acid (GABA) metabolism in vivo. Sprague-Dawley male rats received daily intraperitoneal injections MnCl2 (as 6.55 mg/kg Mn body weight, five days per week for 12 weeks), followed by daily subcutaneous injections of 100, 200, or 300 mg/kg PAS-Na for an additional six weeks. Mn exposure significantly impaired spatial learning and memory ability, as noted in the Morris water maze test, and the following PAS-Na treatment successfully restored these adverse effects to levels indistinguishable from controls. Unexpectedly, PAS-Na failed to recover the Mn-induced decrease in the overall GABA levels, although PAS-Na treatment reversed Mn-induced alterations in the enzyme activities directly responsible for the synthesis and degradation of GABA (glutamate decarboxylase and GABA-transaminase, respectively). Moreover, Mn exposure caused an increase of GABA transporter 1 (GAT-1) and decrease of GABA A receptor (GABAA) in transcriptional levels, which could be reverted by the highest dose of 300 mg/kg PAS-Na treatment. In conclusion, the GABA metabolism was interrupted by sub-chronic Mn exposure. However, the PAS-Na treatment mediated protection from sub-chronic Mn exposure-induced neurotoxicity, which may not be dependent on the GABA metabolism.

Litchi leaf is a good resource for phenolics, which are good candidates for medicines. In this work, three phenolics were isolated from litchi leaf by column chromatography. Their structures were identified by electrospray ionization–mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy as secoisolariciresinol 9′-O-β- D- xyloside (1), 4,7,7′,8′,9,9′-hexahydroxy-3,3′-dimethoxy-8,4′-oxyneolignan (2), and cinnamtannin B1 (3). Cinnamtannin B1 showed better extra- and intracellular antioxidant activities than Compound 1 , Compound 2 . The intracellular antioxidant activity of cinnamtannin B1 was related to the upregulation of endogenous antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase), and inhibition of ROS generation. Furthermore, cinnamtannin B1 exhibited strong antiproliferative effects against HepG2 and Siha cell lines with no significant cytotoxicities. In the case of the HepG2 cell line, cell cycle arrest and apoptosis induction were the underlying anticancer mechanisms of cinnamtannin B1. The results indicated that cinnamtannin B1 was a potent cancer cell proliferation inhibitor and a good intracellular antioxidant.

Two cultivars of Chinese bayberry fruit cvs 'Dongkui' and 'Biqi' with five different ripening stages were used to investigate the relationship between anthocyanin biosynthesis and sugar metabolism during fruit development. The results showed that anthocynin accumulated with the increased ripening stage in both of the two cultivars of bayberries. As compared to 'Biqi' fruit, a higher level of anthocyanin content was observed in 'Dongkui' fruit due to the increased expression of anthocyanin biosynthetic and regulatory genes especially MrCHI, MrDFR1, MrANS, and MrMYB1. Meanwhile, 'Dongkui' fruit also experienced higher levels of soluble sugars including sucrose, glucose, and fructose and expression of genes such as MrSPS1, MrSPS2, MrSPS3, MrINV1, MrINV2, and MrINV3 involved in sugar metabolism. Correlation analysis showed anthocyanin content had a significant relationship with all the three soluble sugars in bayberry fruit. Therefore, our results suggested that the higher anthocyanin content in 'Dongkui' fruit might be associated with its increased levels of soluble sugars.

Fusarium contamination is considered a major agricultural problem, which could not only significantly reduce yield and quality of agricultural products, but produce mycotoxins that are virulence factors responsible for many diseases of humans and farm animals. One strategy to identify toxigenic Fusarium species is the use of modern molecular methods, which include the analysis of DNA target regions for differentiation of the Fusarium species, particularly the mycotoxin-producing Fusarium species such as F. verticillioides and F. graminearum. Additionally, polymerase chain reaction assays are used to determine the genes involved in the biosynthesis of the toxins in order to facilitate a qualitative and quantitative detection of Fusarium-producing mycotoxins. Also, it is worth mentioning that some factors that modulate the biosynthesis of mycotoxins are not only determined by their biosynthetic gene clusters, but also by environmental conditions. Therefore, all of the aforementioned factors which may affect the molecular diagnosis of mycotoxins will be reviewed and discussed in this paper.

Our study aimed to assess the distribution of blood lead level and its relationship to essential elements in preschool children in an urban area of China.A total of 6741 children aged 0- to 6-year-old were recruited. Levels of lead, zinc, copper, iron, calcium, and magnesium in whole blood samples were determined using atomic absorption spectrometry.The mean blood lead level (BLL) and the prevalence of BLL≥10μg/dl (5.26±4.08μg/dl and 6.84%, respectively) increased with age gradually, and there was a gender-difference for blood lead, copper, zinc and iron levels. Compared with the group of children who had BLLs5μg/dl, the groups of 5≤BLLs10μg/dl and 10≤BLLs15μg/dl showed higher blood zinc, iron and magnesium levels, and a lower blood calcium level. A positive correlation of lead with zinc, iron and magnesium, and a negative correlation of lead with calcium were found in the group of children with BLL5μg/dl.Age- and gender-differences were found when assessing the BLL and intoxication prevalence in preschool children. Metabolic disorder of essential elements was found even with a low level of lead exposure.

'Guiwei' litchi fruit were treated with 5 ga.i. L(-1) apple polyphenols (APP) and then stored at 25°C to investigate the effects on pericarp browning. APP treatment effectively reduced pericarp browning and retarded the loss of red colour. APP-treated fruit exhibited higher levels of anthocyanins and cyanidin-3-rutinoside, which correlated with suppressed anthocyanase activity. APP treatment also maintained membrane integrity and reduced oxidative damage, as indicated by a lower relative leakage rate, malondialdehyde content, and reactive oxygen species (ROS) generation. The data suggest that decompartmentalisation of peroxidase and polyphenoloxidase and respective browning substrates was reduced. In addition, APP treatment enhanced the activities of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase), as well as non-enzymatic antioxidant capacity (DPPH radical-scavenging activity and reducing power), which might be beneficial in scavenging ROS. We propose that APP treatment is a promising safe strategy for controlling postharvest browning of litchi fruit.

Increased manganese (Mn) exposure is known to cause cognitive, psychiatric and motor deficits. Mn exposure occurs in different occupational settings, where the airborne Mn level and the size of respirable particulates may vary considerably. Recently the importance of the role of the cerebral cortex in Mn toxicity has been highlighted, especially in Mn-induced neuropsychological effects. In this study we used magnetic resonance imaging (MRI) to evaluate brain Mn accumulation using T1 signal intensity indices and to examine changes in brain iron content using T2* contrast, as well as magnetic resonance spectroscopy (MRS) to measure exposure-induced metabolite changes non-invasively in cortical and deep brain regions in Mn-exposed welders, Mn-exposed smelter workers and control factory workers with no measurable exposure to Mn. MRS data as well as T1 signal intensity indices and T2* values were acquired from the frontal cortex, posterior cingulate cortex, hippocampus, and thalamus. Smelters were exposed to higher air Mn levels and had a longer duration of exposure, which was reflected in higher Mn levels in erythrocytes and urine than in welders. Nonetheless, welders had more significant metabolic differences compared to controls than did the smelter workers, especially in the frontal cortex. T1 hyperintensities in the globus pallidus were observed in both Mn-exposed groups, but only welders showed significantly higher thalamic and hippocampal T1 hyperintensities, as well as significantly reduced T2* values in the frontal cortex. Our results indicate that (1) the cerebral cortex, in particular the frontal cortex, is clearly involved in Mn neurotoxic effects and (2) in spite of the lower air Mn levels and shorter duration of exposure, welders exhibit more extensive neuroimaging changes compared to controls than smelters, including measurable deposition of Mn in more brain areas. These results indicate that the type of exposure (particulate sizes, dust versus fume) and route of exposure play an important role in the extent of Mn-induced toxic effects on the brain.

Strawberry cv. Everest fruit were treated with 1-methylcyclopropene (I-MCP) at various concentrations from 0 to 1000 nl/l for 2 h at 20 degreesC. They were then kept individually in closed but vented containers for 3 days in the dark at 20 degreesC and 95 - 100% relative humidity. 1-MCP treatment tended to maintain strawberry fruit firmness and colour. However. disease development was accelerated in fruit treated at high (500 and 1000 nl/l) I-MCP concentrations. I-MCP treatment also lowered ethylene production. Treatment with I-MCP inhibited phenylalanine ammmonia-lyase (PAL) activity, and lowered increases in anthocyanin and phenolic contents. Comparatively low levels of phenolics in fruit treated at the highest I-MCP concentration (1000 nl/l) could account for decreased disease resistance of these fruit. (C) 2001 Elsevier Science BN. All rights reserved.

Electrical conductivity was investigated in relation to percent pured fruit or damage Indeses prepared by manually paring strawberries and stimulating bruising with a 3-dimensional vibrator. The conductivity was associated with the percent pared fruit (0 to 40%) or damage indexes (1 to 5) of strawberries, with correlation coefficients of 0.938 and 0.917 at P ≤ 0.05, respectively. Furthermore, the bruising caused by the 3-dimensional vibrator resulted in increases in electrical conductivity in response to vibrating time and vibrating force. The decrease in electrical conductivity of strawberries treated with the vibrator during 2 d of storage at 25°C and 80% relative humidity may be due to wound healing of the fruit. Electrical conductivity exhibited potential for quantitatively evaluating damage of strawberries during transportation and marketing. Cette etude evalue la conductivite electrique pour quantifier les dommages causes a des fraises par manipulation manuelle ou par vibration. La conductivite est associee avec le pourcentage de fruits abimes (0 a 40%) et les indices d'alteration (1 a 5) avec des coefficients de correlation de 0,938 et 0,917, respectivement. De plus, les dommages causes par le vibreur a trois dimensions engendrent une augmentation de la conductivite electrique en reponse au temps et a la force de vibration.

Pericarp browning is the main problem of post-harvest litchi fruit, resulting in an accelerated shelf life and reduced commercial value of the fruit. Underhill and Critchley (1994) . Anthocyanin decolorisation and its role in lychee pericarp browning. Australian Journal of Experimental Agriculture , 34 , 115-122 found that there was not an obvious change in the content of anthocyanins when the fruit browned. This work was conducted with a view to explaining this unexpected observation. Litchi pericarp browning index increased while the content of anthocyanins decreased with storage time when 0.1 M HCl was used as the extract solution instead of acidic methanol. The visible spectum of the anthocyanin extract, at a range of 400–600 nm and pH values of 1.0, 3.0 and 5.0, were recorded, with an absorbance peak of about 510 nm. The colour of the extract depended on the pH values and the half-degradation constants for anthocyanins at pHs 1.0, 3.0 and 5.0 were, respectively, 29, 15.3 and 10.5 days, as calculated from the kinetics of the degradation. Compared with the anthocyanin extract, anthocyanidin is more vulnerable, with a half-degradation of about 5.3 min at pH 5.0. Furthermore, the product from the anthocyanidin degradation had a similar structure to catechol (a good substrate for polyphenol oxidase), which, in turn, could accelerate enzymatic browning reaction by the enzyme polyphenol oxidase. In addition, an anthocyanase, catalyzing anthocyanin hydrolysis and producing anthocyanidin was extracted from litchi fruit pericarp. High activity of the enzyme was observed in the pericarp. Thus, it is suggested that anthocyanase might contribute to the browning of litchi pericarp involved in the anthocyanase-anthocyanin-PPO reaction.

The litchi ( Litchi chinensis Sonn.) fruit are extremely susceptible to postharvest moulds. The main pathogen of litchi fruit was isolated and identified as Peronophythora litchi . Of antagonists tested, Bacillus subtilis was the most effective against Peronophythora litchi . The relative antifungal activity of Bacillus subtilis reached a maximum after 48 h culture, and then decreased gradually. Purification of the crude extract of Bacillus subtilis followed by a Sepharose Toyopearl HW-50 gel filtration confirmed that the antifungal compound of Bacillus subtilis had a molecular weight of about 1.2 kD. Both the antagonist and its extract were effective in controlling artificially wound-inoculated fruit pathogens, but the use of the extract had better effect than that of the antagonist. Furthermore, application of the extract of Bacillus subtilis exhibited good control of decay for a storage period of 30 days at 5 °C and quality maintenance of litchi fruit in terms of eating scores and contents of total soluble solids, titratable acidity and ascorbic acid. No off-flavor of the treated fruit was tasted.

The perovskites of La2/3Ca1/3MnO3 (LCMO) and La2/3Sr1/3MnO3 (LSMO) were synthesized by the sol-gel method. The two perovskites were mixed into polycrystalline materials, (1-m)LCMO + mLSMO, where m is the relative weight ratio of LSMO. The compound with m~0.3-0.5 has the lowest semiconductor-metal transition temperature Tp and the largest low-T resistivity. Moving away from this ratio, Tp increases while the low-T resistivity decreases with increasing or decreasing m. Measurements of the magnetoresistance (MR) show that the mixed polycrystals exhibit a sizable MR effect in low magnetic fields which increases upon cooling and reaches its largest value for T?0?K. It is also interesting to observe the almost T-independent MR effect over a wide temperature window below 300?K for the mixed materials with smaller m.

The effects of chitosan coating in extending postharvest life of longan fruits and maintaining their quality were investigated. The fruits were treated with aqueous solutions of 0.5, 1.0 and 2.0% chitosan, respectively, and then stored at 2°C and 90% relative humidity. Changes in respiration rate, polyphenol oxidase (PPO) activity, colour, eating quality, and weight loss were measured. The effect of chitosan coating on disease incidence was also evaluated. The application of chitosan coating reduced respiration rate and weight loss, delayed the increase in PPO activity and the changes in colour, and eating quality, and partially inhibited decay of fruit during storage. Furthermore, increasing the concentration of chitosan coating enhanced the beneficial effects of chitosan on postharvest life and quality of the fruit.

Longan fruit has attracted much attention by consumers over the world due to the unique sweet–sour taste. However, the fruit brown rapidly at ambient temperature during storage, due to enzyme-catalyzed reaction of phenolics. Experiments were conducted to understand the variations in the levels of total phenolics and (−)-epicatechin as a major substrate for polyphenol oxidase (PPO) in pericarp tissue of longan fruit during development. The activities of phenylalanine ammonialyase (PAL) and PPO, involved in the synthesis and oxidation of (−)-epicatechin, respectively, during longan fruit development were also measured. During fruit development, the content of total phenolics decreased rapidly and then increased while the content of (−)-epicatechin tended to decrease. Both PAL and PPO activities decreased rapidly at the early fruit development and increased later but the increase of the former appeared was 10 days earlier than the latter. Thus, the level of (−)-epicatechin depended largely on PAL activity but it could involve the conversion of (−)-epicatechin into other flavonoids. This study could help develop appropriate preharvest treatments to control pericarp browning of harvested longan fruit by understanding the variation in the level of the major browning substrate during development.

Further chemical investigation of the whole plants of Gentiana loureirii led to the isolation and characterization of three new compounds, cyclic 4-O-beta-D-glucopyranosylcaffeic acid dimer (1), a new alpha-tetralone, 4-hydroxy-6-methyl-alpha-tetralone 4-O-beta-D-glucopyranoside (2), and 3beta,30-dihydroxy-12-ursen-28-oic acid 28-O-beta-D-glucopyranosyl ester (3), along with five known compounds. To the best of our knowledge, compound 1 is the first cyclic phenolic acid glycoside dimer.

The minimum supply voltage for implementing a typical bandgap reference is usually over 1.8 V. This minimum is mainly due to the limited input common-mode range of the opamp used in the bandgap reference. In this work, a low-voltage bandgap reference using a transimpedance amplifier that does not have this limitation is proposed and some of the design considerations for the proposed technique are briefly discussed. Based on this technique, a 1.2-V bandgap reference was implemented in a 1.2-/spl mu/m CMOS process (V/sub TN//spl ap/0.53 V and V/sub TP//spl ap/-0.91 V) with bipolar option. The variations of the output voltage over temperature (0/spl deg/C/spl les/T/spl les/100/spl deg/C) were measured to be less than /spl plusmn/1%.

The role of abscisic acid (ABA) in banana fruit ripening was examined with the ethylene binding inhibitor, 1-methylcyclopropene (1-MCP). ABA (0, 10(-5), 10(-4), or 10(-3) mol/L) was applied by vacuum infiltration into fruit. 1-MCP (1 µL/L) was applied by injecting a measured volume of stock gas into sealed glass jars containing fruit. Fruit ripening, as judged by ethylene evolution and respiration associated with color change and softening, was accelerated by 10(-4) or 10(-3) mol/L ABA. ABA at 10(-5) mol/L had no effect. The acceleration of ripening by ABA was greater at 10(-3) mol/L than at 10(-4) mol/L. ABA-induced acceleration of banana fruit ripening was not observed in 1-MCP treated fruit, especially when ABA was applied after exposure to 1-MCP. Thus, ABA's promotion of ripening in intact banana fruit is at least partially mediated by ethylene. Exposure of ABA-treated fruit to 0.1 µL/L ethylene for 24 h resulted in increased ethylene production and respiration, and associated skin color change and fruit softening. Control fruit (no ABA) was unresponsive to similar ethylene treatments. The data suggest that ABA facilitates initiation and progress in the sequence of ethylene-mediated ripening events, possibly by enhancing the sensitivity to ethylene.