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1.
Food Chem ; 305: 125439, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31499287

RESUMO

Compared to the control longans, hydrogen peroxide (H2O2)-treated longans exhibited higher index of pulp breakdown, higher fruit respiration rate, higher activities of pulp phosphohexose isomerase (PGI), succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), ascorbic acid oxidase (AAO) and polyphenol oxidase (PPO), but lower activity of pulp nicotinamide adenine dinucleotide kinase (NADK). H2O2-treated longans also exhibited lower total activities of pulp glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-PGDH), lower levels of pulp NADP(H), but higher levels of pulp NAD(H). These data indicated that H2O2-stimulated longan pulp breakdown was owing to a decreased proportion of pentose phosphate pathway (PPP), the increased proportions of Embden-Meyerhof-Parnas pathway (EMP), tricarboxylic acid (TCA) cycle and cytochrome pathway (CCP) in total respiratory pathways. These findings further revealed that H2O2 could enhance respiration rate, and thus accelerate pulp breakdown occurrence and shorten the shelf life of longan fruit.

2.
Food Chem ; 306: 125627, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31610328

RESUMO

Effects of various concentrations of Kadozan (chitosan) treatment on storability and quality properties of harvested 'Fuyan' longans were investigated. Compared to the control samples, Kadozan treated-longans displayed lower fruit respiration rate, lower pericarp cell membrane permeability, pericarp browning index, pulp breakdown index, fruit disease index, and weight loss, but higher rate of commercially acceptable fruit, higher levels of pericarp chlorophyll, carotenoid, anthocyanin, flavonoid and total phenolics, higher amounts of pulp total soluble sugar, sucrose, total soluble solids, and vitamin C. These results revealed Kadozan treatment could increase storability and retain better quality of harvested longan fruit. Among different concentrations of Kadozan, the dilution of 1:500 (VKadozan: VKadozan + Water) showed the best results in storability and maintained the best quality of longans during storage. These findings demonstrated that Kadozan could be a facile and eco-friendly postharvest handling approach for increasing storability and lengthening shelf-life of harvested 'Fuyan' longan fruit.

3.
Food Chem ; 297: 124955, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253342

RESUMO

This study aimed to investigate the effect of hydrogen peroxide (H2O2) on membrane lipids metabolism and its relation to pulp breakdown development of longan fruit during postharvest storage. Compared to the control longans, H2O2-treated longans showed higher pulp breakdown index, cell membrane permeability, and activities of phospholipase D (PLD), lipase and lipoxygenase (LOX). Moreover, H2O2-treated longans maintained higher levels of pulp phosphatidic acid (PA) and saturated fatty acids (SFA). However, H2O2-treated longans exhibited lower levels of pulp phosphatidylcholine (PC), phosphatidylinositol (PI) and unsaturated fatty acids (USFA), lower index of unsaturated fatty acids (IUFA), and lower ratio of USFA to SFA (U/S). These findings demonstrated that H2O2 caused the increased activities of enzymes involving in membrane lipids degradation and the accelerated decompositions of membrane USFA and phospholipids in longan pulp, which eventually triggered the destruction of the pulp cell membrane structure and the development of pulp breakdown in longans during storage.


Assuntos
Enzimas/metabolismo , Frutas/química , Peróxido de Hidrogênio/farmacologia , Lipídeos de Membrana/metabolismo , Sapindaceae/química , Enzimas/química , Ácidos Graxos/análise , Ácidos Graxos/química , Armazenamento de Alimentos , Frutas/efeitos dos fármacos , Frutas/metabolismo , Peróxido de Hidrogênio/química , Lipase/química , Lipase/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipoxigenase/química , Lipoxigenase/metabolismo , Lipídeos de Membrana/química , Fosfolipase D/metabolismo , Fosfolipídeos/química , Fosfolipídeos/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Sapindaceae/efeitos dos fármacos , Sapindaceae/metabolismo
4.
Food Microbiol ; 78: 188-193, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30497602

RESUMO

The US Produce Safety Rule allows for use of water that does not meet its microbial standards if corrective measures are employed. This research was initiated to determine the suitability of nonpathogenic Escherichia coli as a surrogate for Salmonella during citrus washing, and to evaluate the removal of E. coli from grapefruit on two pilot packinglines (CREC and IRREC) as corrective measures. Whole grapefruit were inoculated with either E. coli or Salmonella and dried, and exposed to a variety of treatments on a lab-scale brush wash system. Individual processes were evaluated on the pilot packinglines with E. coli only. In all lab-scale brush wash system treatments, bacterial population reductions between E. coli and Salmonella were not significantly different (P ≤ 0.05). On pilot packinglines, E. coli populations were reduced by 3.59 to >5.11 log CFU/grapefruit at the CREC packingline, and by 3.30 to >5.13 log CFU/grapefruit at the IRREC packingline. Treatment of fruit through complete packingline processing at both locations reduced E. coli populations to levels below the detection limit (<1 log CFU/grapefruit). The studies indicate E. coli is an appropriate surrogate for Salmonella under tested conditions, and that standard citrus packingline processes can be used as a corrective measure.


Assuntos
Citrus paradisi/microbiologia , Escherichia coli O157/isolamento & purificação , Manipulação de Alimentos , Frutas/microbiologia , Salmonella/isolamento & purificação , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Embalagem de Alimentos , Temperatura Ambiente
5.
J Agric Food Chem ; 2018 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-30403851

RESUMO

This study investigated the changes in metabolisms of membrane lipids and phenolics caused by Phomopsis longanae Chi infection in association with pericarp browning and fruit disease occurrence of postharvest longans. Compared with the uninoculated-longans, the longans inoculated by P. longanae exhibited higher cellular membrane permeability; higher PLD, lipase, and LOX activities; and higher levels of saturated fatty acids (SFAs) and phosphatidic acid but lower levels of phosphatidylinositol, phosphatidylcholine, and unsaturated fatty acids (USFAs). Additionally, the longans inoculated by P. longanae showed higher activities of POD and PPO but a lower amount of total phenolics. These findings suggested that infection of P. longanae enhanced activities of PLD-, lipase-, and LOX- stimulated degradations of membrane lipids and USFAs, which destroyed the integrity of the cell membrane structure, resulting in enzymatic browning by contact of phenolics with POD and PPO, and resulting in reduction of resistance to pathogen infection and accordingly accelerated disease occurrence of postharvest longan fruit.

6.
Food Chem ; 269: 644-651, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30100484

RESUMO

Compared to P. longanae-inoculated longan fruit, DNP-treated P. longanae-inoculated longans displayed higher fruit disease index, pericarp browning index and cell membrane permeability. Moreover, they exhibited higher activities of phospholipase D, lipase and lipoxygenase, lower amounts of phosphatidylcholine, phosphatidylinositol and USFA (unsaturated fatty acids) as well as higher amounts of phosphatidic acid and SFA (saturated fatty acids). Additionally, lower ratio of USFA to SFA and USFA index were shown in DNP-treated P. longanae-inoculated longans. However, ATP-treated P. longanae-inoculated longans exhibited the opposite results. These findings indicated that DNP stimulated longan pericarp browning and disease development caused by P. longanae resulted from the increases in activities of membrane lipids-degrading enzymes, promoting degradation of membrane phospholipids and USFA, and disruption of membrane structural integrity. Whereas, the opposite results observed in ATP-treated P. longanae-inoculated longans were due to the reduction in activities of membrane lipids-degrading enzymes and the maintenance of membrane structural integrity.

7.
Food Chem ; 225: 31-36, 2017 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-28193430

RESUMO

Energy metabolism of "Fuyan" longan fruit treated with hydrogen peroxide (H2O2), the most stable of the reactive oxygen, and its relationship to pericarp browning were investigated in this work. The results displayed that H2O2 significantly decreased contents of adenosine triphosphate (ATP) and adenosine diphosphate (ADP). It also inhibited activities of H+-ATPase, Ca2+-ATPase and Mg2+-ATPase in membranes of plasma, vacuole and mitochondria during the early-storage and mid-storage (except for mitochondrial membrane Mg2+-ATPase). These results gave convincing evidence that the treatment of H2O2 accelerating pericarp browning in harvested longans was due to a decrease of ATPase activity and available ATP content. This might break the ion homeostasis and the integrity of mitochondria, which might reduce energy charge and destroy the function and compartmentalization of cell membrane. These together aggravated browning incidence in pericarp of harvested longan fruit.


Assuntos
Metabolismo Energético/efeitos dos fármacos , Frutas/metabolismo , Peróxido de Hidrogênio/farmacologia , Sapindaceae/metabolismo , Difosfato de Adenosina/análise , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/análise , Trifosfato de Adenosina/metabolismo , Frutas/química , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Sapindaceae/efeitos dos fármacos
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