Effects of 1-methylcyclopropene on skin greasiness and quality of'Yuluxiang'pear during storage at 20℃

During storage at 20℃,specific pear cultivars may exhibit a greasy texture and decline in quality due to fruit senescence.Among these varieties,‘Yuluxiang’is particularly susceptible to peel greasiness,resulting in significant economic losses.Therefore,there is an urgent need for a preservative that can effectively inhibit the development of greasiness.Previous studies have demonstrated the efficacy of 1-methylcyclopropene(1-MCP)in extending the storage period of fruits.We hypothesize that it may also influence the occurrence of postharvest peel greasiness in the‘Yuluxiang’pears.In this study,we treated‘Yuluxiang’pears with 1-MCP.We stored them at 20℃while analyzing the composition and morphology of the surface waxes,recording enzyme activities related to wax synthesis,and measuring indicators associated with fruit storage quality and physiological characteristics.The results demonstrate that prolonged storage at 20℃leads to a rapid increase in skin greasiness,consistent with the observed elevations in L^(*),greasiness score,and the content of total wax and greasy wax components.Moreover,there were indications that cuticular waxes underwent melting,resulting in the formation of an amorphous structure.In comparison to controls,the application of 1-MCP significantly inhibited increments in L^(*) values as well as grease scores while also reducing accumulation rates for oily waxes throughout most stages over its shelf period,additionally delaying transitions from flaky-wax structures towards their amorphous counterparts.During the initial 7 d of storage,several enzymes involved in the biosynthesis and metabolism of greasy wax components,including lipoxygenase(LOX),phospholipase D(PLD),andβ-ketoacyl-CoA synthase(KCS),exhibited an increase followed by a subsequent decline.The activity of LOX during early shelf life(0–7 d)and the KCS activity during middle to late shelf life(14–21 d)were significantly suppressed by 1-MCP.Additionally,1-MCP effectively maintained firmness,total soluble solid(TSS)and titratable acid(TA)contents,peroxidase(POD),and phenylalanine ammonia-lyase(PAL)activities while inhibiting vitamin C degradation and weight loss.Furthermore,it restrained polyphenol oxidase(PPO)activity,ethylene production,and respiration rate increase.These findings demonstrate that 1-MCP not only delays the onset of peel greasiness but also preserves the overall storage quality of‘Yuluxiang’pear at a temperature of 20℃.This study presents a novel approach for developing new preservatives to inhibit pear fruit peel greasiness and provides a theoretical foundation for further research on pear fruit preservation.

Effects of Peracetic Acid(PAA) Combined with Calcium Treatments on Storage Quality of Loquat Fruit

[Objective] The paper was to evaluate effects of peracetic acid （PAA） combined with calcium treatments on storage quality of Ioquat fruits, so as to pro- vide practical techniques to solve the problems of postharvest rot and quality deteri- oration for Ioquat fruits. [Method] With Ioquat fruits of Qingzhong variety as materi- als, 0.2%, 0.4% and 0.8% PAA combined with 0.8% CaCI2 was used to soak Ioquat fruits for 4 min, 0.8% CaCl2 and water treatments were set as two controls; the fruits were dried and packaged by 0.02 mm PE bags, then stored under non-chilling low temperature of （7±1） ℃. The indicators related to storage quality of Ioquat fruits were randomly tested once every 3 d, and their variation situations were analyzed. [Result] Compared with two control treatments and 0.2% PAA, 0.8% PAA combined with calcium treatments, the treatment of 0.4% PAA combined with 0.8% CaCl2 could significantly inhibit rot index, weight loss rate, firmness and cell membrane permeability of Ioquat fruits during storage period, which could also effectively delay the reduction of titratable acid, vitamin C, soluble solid content and juice yield, and maintain respiration intensity of fruits at a low level; the appearance and flavor qual- ity of fruits were good after stored for 25 d. [Conclusion] 0.4% PAA combined with 0.8% CaCl2 treatment is an efficient, safe and economical practice technology in an- ti-corrosion and quality preservation for postharvest Ioquat fruits .

Effects of Chlorine Dioxide Gas on Postharvest Physiology and Storage Quality of Green Bell Pepper (Capsicum frutescens L.var.Longrum)

The effects of treatment of chlorine dioxide （C1Oz） gas on postharvest physiology and preservation quality of green bell peppers were studied. Green bell peppers were collected in bags and treated with 0, 5, 10, 20, and 50 mg L^-1 ClO2 gas at 10±0.5℃ for over 40 d, and the changes in postharvest physiology and preservation quality of the peppers were evaluated during the storage. The inhibition of rot of the peppers was observed for all the tested ClO2 gas treatments. The rot rates of the treated samples were 50% lesser than those of the control after day 40 of storage. The highest inhibitory effect was obtained after 50 mg L^-1 ClO2 gas treatment, where the peppers did not decay until day 30 and showed only one-fourth of the rot rate of the control at day 40 of storage. The respiratory activity of the peppers was significantly （P〈0.05） inhibited by 20 and 50 mg L^-1 ClO2 treatments, whereas no significant effects on respiratory activity were observed with 5 and 10 mg L^-1 ClO2 treatments （P〉0.05）. Except for 50 mg L^-1 ClO2, malondialdenyde （MDA） contents in the peppers treated with 5, 10, or 20 mg L^-1 ClO2 were not significantly （P〉0.05） different from those in the control. Degradation of chlorophyll in the peppers was delayed by 5 mg L-1ClO2, but promoted by 10, 20, or 50 mg L^-1 ClO2. The vitamin C content, titratable acidity, and total soluble solids of the peppers treated by all the tested ClO2 gas did not significantly change during the storage. The results suggested that ClO2 gas treatment effectively delayed the postharvest physiological transformation of green peppers, inhibited decay and respiration, maintained some nutritional and sensory quality, and retarded MDA accumulation.

Terminalia arjuna:A novel natural preservative for improved lipid oxidative stability and storage quality of muscle foods

The study was conducted to explore the possibility of utilization of Terminalia arjuna as a novel natural preservative in meat products by using chevon sausages as a model system.Chevon sausages were prepared by incorporating different levels of T.arjuna viz.T1(0.25%),T2(0.50%)and T3(0.75%)and were assessed for various lipid oxidative stability and storage quality parameters under refrigerated(4±1◦C)conditions.T.arjuna showed a significant(p<0.05)effect on the lipid oxidative stability as the treated products exhibited significantly(p<0.05)lower TBARS(mg malonaldehyde/kg)values in comparison to control.A significant(p<0.05)effect was also observed on the microbial stability as T.arjuna incorporated products showed significantly(p<0.05)lower values for total plate count(log cfu/g),psychrophilic count(log cfu/g),yeast and mould count(log cfu/g)and FFA(%oleic acid)values.Significantly(p<0.05)higher scores were observed for various sensory parameters of the products incorporated with T.arjuna during refrigerated storage.T.arjuna successfully improved the lipid oxidative stability and storage quality of the model meat product and may be commercially exploited as a novel preservative in muscle foods.

Relationship of chemical properties of different peanut varieties to peanut butter storage stability

This study examined the effect of peanut quality on the storage stability of peanut butter. The quality of 17 varieties of peanuts was analyzed, and each was used to prepare peanut butter. For different storage temperatures and durations, stability of the peanut butter was measured according to three indicators： peroxide value, acid value, and centrifugal rate. The correlation between peanut components and peanut butter storage stability was also investigated. The results indicated significant differences in fatty acid composition between different varieties of peanut. Peanut butter prepared with high oleic peanuts（Kainong 17-15） had a significantly longer shelf life than that of other varieties. The significant correlation between the stability of peanut butter and peanut quality suggests that oleic acid and linoleic acid were the main influencing factors on stability. This study finds that the high oleic peanuts（HOP） is the most suitable variety for making peanut butter, which can allow farmers and processors to choose the specific variety for better product and shelf life.

Application of a chitosan coating as a carrier for natamycin to maintain the storage quality of ground cherry(Physalis pubescens L.)

Ground cherry(Physalis pubescens L.) is a kind of berry fruit favored by consumers in China; however, this fruit is particularly vulnerable to physiological senescence and pathogen attack during the traditional cold storage period. In order to maintain storage quality, a 1.5%(w/w) chitosan(CS) water solution containing 50 mg/L of natamycin(NA) was introduced. After all treatments were completed, the fruit was stored at 0°C and sampled every 10 d. At each sampling date, the following tests were performed: mold and yeast analyses; enzyme activity and content analyses which included superoxide dismutase(SOD), ascorbate peroxidase(APX), and malondialdehyde(MDA); and color analysis. In addition, a sensory evaluation was carried out for quality assessment at the end of the storage period. The results showed that the application of a chitosan coating combined with natamycin(CSNA) enhanced the activity of superoxide dismutase(SOD) and ascorbate peroxidase(APX), reduced the physiological rate of senescence, and inhibited pathogen attack. Thus, CSNA treatment can maintain ground cherries at an acceptable level of storage quality for 50 d.

Melatonin maintains the storage quality of fresh-cut Chinese water chestnuts by regulating phenolic and reactive oxygen species metabolism

Fresh-cut Chinese water chestnuts(CWCs)are prone to quality deterioration during storage,which does not meet consumer demand.In this study,the effect of exogenous melatonin(5 mmol·L^(-1))on the quality and potential mechanisms in fresh-cut CWC was investigated.The results showed that melatonin treatment alleviated the cut-surface discoloration of CWCs.Not only did this treatment significantly slow down the in-crease in browning degree and yellowness(b*)as well as the decrease in lightness(L*),but it also significantly delayed the loss of weight and total soluble solids.Further investigations indicated that melatonin-treated fresh-cut CWCs exhibited significantly lower total phenolics and soluble quinones and suppressed the activities of phenylalanine ammonia-lyase,polyphenol oxidase,and peroxidase.Meanwhile,when fresh-cut CWCs were treated with melatonin,the total flavonoid concentration was significantly decreased compared to the control.Ad ditionally,melatonin significantly inhibited the accumulation of H_(2)O_(2)and malondialdehyde as well as enhanced the activities of superoxide dismutase and catalase by promoting the production of O_(2)^(-·).In summary,melatonin treatment may delay the surface discoloration of fresh-cut CWCs by inhibiting phenolic compound metabolism and improving antioxidant capacity,thereby effectively maintaining the quality and prolonging the shelf life of fresh-cut CWCs.

Effect of Sodium Selenite-Chitosan Compound Preservative on Storability of Kumquats

[Objectives]To explore the effect of sodium selenite-chitosan compound preservative on storability of kumquats.[Methods]Under the condition of room temperature,fresh kumquats were coated with different concentrations of sodium selenite-chitosan compound preservative,respectively.[Results]Sodium selenite-chitosan compound preservative reduced the weight loss rate,delayed the decline of vitamin C,soluble solids,titratable acid and GSH contents,slowed down the accumulation of MDA,inhibited the increase of PPO activity,and increased to a certain extent the activity of SOD in fresh kumquats.[Conclusions]Sodium selenite-chitosan compound preservative maintained the quality and prolonged the shelf life of kumquats.The preservation effect of compound preservative composed of 4 mg/L sodium selenite and 8 g/L chitosan was the best.

Effect of Internal Ethylene and 1-methylcyclopropene on Ripening of Papaya Fruit(Carica papaya L.)

With papaya fruit （ Carica papaya ） as an experimental material, variations of its physiological indices were investigated through hypobaric hypoxia （HH, 10 kPa, 1.5 kPa O 2） treatment followed by fumigation with 1-methylcyclopropene （1-MCP）, so as to discuss the effect of interaction between 1-MCP and internal ethylene on ripening of papaya fruit during postharvest storage. The results indicated that HH treatment significantly reduced internal ethylene concentration （IEC） by 57.6%. However, there were no remarkable differences in other physiological indices between various treatments and control （CK）. The 1-MCP and HH＋1-MCP treatments could significant postpone the softening process and color change of papaya fruit. The two treatments achieved the effects of significantly inhibiting the occurrence of fruit disease and the increase of pericarp cell membrane permeability, effectively delaying the variation of soluble solid and Vc contents, and better maintaining soluble solid and Vc contents in fruit, thereby better keeping nutritional substances and flavor quality in fruit in later storage period and prolonging the storage time of fruit.

Combined effect of Bacillus siamensis and chlorogenic acid on maintenance of quality and control of disease in stored wax apple fruit

Objectives:The purpose of this study was to evaluate the effect of combined postharvest use of Bacillus siamensis strain and chlorogenic acid on quality maintenance and disease control in wax apple fruit.Materials and Methods:Wax apple fruit were treated with Bacillus siamensis strain(N1),chlorogenic acid(CHA)and N1+CHA and preserved at 25℃ for 12 d.The appearance and quality parameters were evaluated,along with the disease index,content of total soluble solids(TSS),total acid(TA),vitamin C(Vc),total phenolic,and flavonoids during cold storage.Meanwhile,the activities ofβ-1,3-glucanase(GLU),phenylalanine ammonialyase(PAL),polyphenol oxidase(PPO),and peroxidase(POD)were determined.Furthermore,the transcriptome and the expression level of key defense enzyme genes were analyzed by RNA-seq and real-time quantitative reverse transcription polymerase chain reaction.Results:N1+CHA treatment significantly lowered DI and delayed fruit quality deterioration by slowing TSS and TA loss and enhancing anti-oxidant capacity,including Vc,total phenolic,and flavonoids content.Meanwhile,the activities of GLU,PAL,PPO,and POD were dramatically increased by N1+CHA treatment.Additionally,N1+CHA treatment modulated several metabolic pathways,including those involved in planthormone signal transduction and plant–pathogen interaction.The expression levels of key defense enzyme genes were significantly upregulated in stored wax apple fruit by the N1+CHA treatment,which were well coincided with the transcriptome data.Conclusions:The combined use of N1+CHA significantly prevents disease and maintains fruit quality of wax apple during storage.These findings indicate that it could serve as a promising biological technique for preserving wax apple fruit.

Preservative effects of the combined treatment of slightly acidic electrolyzed water and ice on pomfret

This study assessed the combined effect of slightly acidic electrolyzed water(SAEW)and slightly acidic electrolyzed water ice(SAEW-ice)on the quality of pomfrets over a period of 18 d of cold storage at 4°C.A presoak for 5 min in SAEW solution(22 mg/L)was used before the pomfrets were placed on SAEW-ice(pH:6.45;ORP:803 mV;ACC:18 mg/L);The changes in physicochemical properties(i.e.,pH,thiobarbituric acid,total volatile basic nitrogen and texture profile),microbial loads and sensory characteristics were all analyzed.Compared with the tap water(TW)group,the total bacterial counts of the SAEW group significantly decreased by 1.27 log10 CFU/g after immersion(p<0.05).The shelf life of the pomfrets was prolonged by 9 d by the combined treatment of SAEW and SAEW-ice during storage at 4℃.On the 18th day,the gumminess and chewiness values of the pomfrets in the SAEW+SAEW-ice group were 195 g and 3.97 mJ,respectively,which were significantly higher than those of the other groups(p<0.05).The results suggested that SAEW+SAEW-ice treatments have great potential as a novel method to maintain the quality and extend the shelf life of pomfrets during refrigerated storage.