| Peach fruit has flesh soft,thin skin,juiciness and was harvest at July and August with strong respiratory intensity and metabolic process.The peach appear softening,dehydrate,rot,withering and browning quickly,and it is hard to ensure the goods value in postharvest distribution and sale.Now,most study of peach mainly concentrated in two aspects of precooling and storage,and little research on the entire postharvest cold chain.So,this paper based on the study of different storage temperature on the quality of peach studyed the different ways of precooling,storage,transportation,sales and home preservation on quality of peach,aiming to provide theoretical basis and technical reference for cold chain logistics.The results of this study are as follows:1.During storage,physical and nutritional parameters were monitored to evaluate the effects of temperature on ‘Okubao’ peach quality under 0℃,5℃,10℃,15℃,20℃,25℃ and 30℃.Results revealed that the storage life of peach was 28,21,12,8,4,3 and 2 days,respectively.The shelf life was longer at the lower storage temperature.20℃,25℃,30℃ stored fruits softened and deteriorated rapidly and resulted in a large amount of decay,weight loss and poor market quality.Conversely,peach held at low temperatures,especially for 0℃,all changes related with loss of quality were significantly reduced and delayed with time.Peaches stored in 0℃showed the highest sensory quality score,least weight loss and decay,reduced respiration rate and ethylene production and significantly remained soluble solids content,titratable acidity and ascorbic acid concentration.Additionally,the use of 0℃retarded softening,maintained color,slowed down changes associated with ripening,such as malondialdehyde content and polyphenol oxidase(PPO)enzyme activity.Thus,peach stored in 0℃had prolonged storability up to 28 days with high quality attributes and nutritional values.2.In the present work,chilling injury(CI)incidence and quality parameters were analyzed in peaches stored at 0℃,2℃,5℃ and 8℃ for28 days,to evaluate the effects of four different temperatures on the keeping quality of ‘Okubao’ peach.The extreme susceptibility of ‘Okubao’peach to CI at 5℃was confirmed by extensive woolliness and decay.Peaches stored at 5℃develop noticeable CI symptom after one to two weeks,while significantly less woolliness occurred after storage 8℃,the temperature at which the highest rate of decay was found.Minimum loss of weight and firmness,optimum sensory quality were obtained by the prolonged storage at 0 ℃.0 ℃ was the most effective treatment in alleviating chilling injury by controlling membrane permeability,inhibiting respiration rate and slowing down polyphenol oxidase(PPO)and peroxidase(POD)activities.Results indicated that fruit held at 0℃can be stored for at least four weeks,and possibly five weeks without much injury.3.Effect of various pre-cooling methods on quality of peaches.In the present work,the effects of various precooling methods on the keeping quality of ‘Okubao’ peaches were evaluated.Fruits were precooled to 5℃by forced-air cooling,precooler cooling,and hydro-cooling,respectively.The results indicated that precooling improved fruit quality and peach precooled by forced-air showed the highest sensory quality score,maintenance in firmness,color and nutritional quality(soluble solids,titratable acidity,soluble sugar contents and ascorbic acid concentration),and prevented decay development and weight loss.It took 140,215,37,minutes,respectively,for forced-air cooling,precooler cooling and hydro-cooling.Although hydro-cooling was the most rapid cooling method,peach showed high rate of deterioration.Among all of the precooling methods used,forced-air is the most suitable method in terms of cooling time and fruit quality.4.The goal of this study was to compare the effects of modified atmosphere packaging(MAP),on the quality of peach fruit.After harvest,peaches were subjected to MAP treatments by using 35 um anti-fogging cast polypropylene(CPP),30 um polyethylene(PE)and 88 um antibacterial film and then kept at 0±0.1℃and 90±5% for 49 days,while peaches stored for 35 days with unpackaged as control(CK).Physical and chemical changes [woolliness incidence,weight loss,healthy fruit index,color,flesh firmness,soluble solids contents(SSC),titratable acidity(TA),ascorbic acid,ethylene production and respiration rate,activities of polyphenol oxidase(PPO)and peroxidase(POD)were recorded at harvest and every 7 days of storage.Fruit flesh firmness significantly decreased during storage for all treated fruits while MAP maintained firmer than control.Compared with CK,MAP showed significantly reduced incidence of woolliness and PPO,POD activities,as well as higher hue angles,SSC,TA,ascorbic acid contents and lower ethylene production and respiration rates.Peach could be stored for 28 days and 35 days by PE and antibacterial film,respectively,while stored successfully for up to 42 days using the CPP material.Peaches stored in CK maintained marketable for 21 days.These results showed that MAP resulted in a considerable improvement in keeping postharvest quality and providing longer storage,while CPP exerted the best effect.5.In order to evaluate the effects of controlled atmosphere(CA)conditions on postharvest preservation of the ‘Okubao’ peach cultivar,particularly focusing on the occurrence of chilling injury and sensory acceptance,three different conditions of CA(CA1,CA2,CA3)were applied when stored at 0℃and 90±5% relative humidity during 35 days in air(CK)and 63 days in CA conditions.Physicochemical parameters were detected at harvest time as well as during the storage period with 7-day intervals at the different tested treatments.Results showed that the use of CA treatments particularly CA2 effectively preserved overall quality of peaches during cold storage,showing decreased incidence of woolliness,relative conductivity and weight loss,adequate healthy fruit and flesh firmness at the end of storage,while the lowest and highest fruit firmness was found to be 17.9 N and 32.2 N in CK and CA2 treatment,respectively.Sensory evaluation scores decreased significantly with the extending storage.Higher consumer acceptance was found for fruits stored at CA1 and CA2,particularly CA2 effectively kept commercial quality during 56 days of cold storage,while CK treatment did not present marketable conditions after 28 days of cold storage.In addition,the supply of soluble solid contents,ascorbic acid and titratable acidity of fruits decreased during the storage period.The ethylene production level was substantially lower(0.003 μL·kg-1·h-1)than that of control fruits(0.0145 μL·kg-1·h-1).The activities of PPO and POD were inhibited in CA-treated fruits,and CA2 had a major effect.It’s concluded that CA especially CA2 condition can dramatically increase fruit quality benefits as well as extend commercial availability.6.The goal of this research was to evaluate the efficiency of various simulated transport treatments on maintaining the quality of peach.Peaches were pre-cooled to 5℃for 140 minutes and afterwards treated with three simulated transport treatments,consisting of cold transportation with or without 35 μm anti-fogging cast polypropylene(CPP)plastic package,and detachable incubator.Parameters evaluated included sensory quality,weight loss,color,flesh firmness,soluble solids content,titratable acidity,soluble sugar and ascorbic acid concentration.Weight loss of fruits was reduced tremendously,lower than 1%.The appearance,soluble solids content,titratable acidity,soluble sugar and overall sensory quality of the wrapped peaches transported at 0℃ were found to be better than those unwrapped and transported by incubator.Transportation at 0℃ in CPP was shown most useful to prevent weight losses and maintain fruit color,freshness and nutritional values.7.The objective of this experiment was to evaluate the effects of different retailing methods on the maintenance of peach quality after pre-cooled to 5℃ and transportation at 0℃.‘Okubao’ peaches were film wrapped using 35μm anti-fogging cast polypropylene(CPP)and stored for3 days at 0℃ or 4℃ to simulate refrigerated display cabinet condition.Some other peached directly stored at 20℃ unwrapped after transportation.Results revealed that softening and deterioration occurred quickly in 20℃.Peach stored in 20℃ lost significantly more weight,3.7%.0℃ and 4℃resulted in less weight loss of the packaged peach,0.7% and 1.7%,respectively.After shelf life,0℃ retailed peach wrapped in CPP showed the highest sensory quality,lost less weight,was firmest,and retained color better than either 4℃ or 20℃ retailed peach.Additionally,soluble solids content,titratable acidity,soluble sugar and ascorbic acid concentration significantly remained when retailed at 0℃.8.In order to evaluate the effects of different household preservation methods on maintaining the fruit quality of the ‘Okubao’ peaches,fruits were either stored in domestic refrigerator at 4℃ or room temperature(20℃)wrapped or unwrapped using 35μm anti-fogging cast polypropylene(CPP).Physical and chemical changes were recorded each day during household preservation.The results demonstrated that wrapped peach placed in domestic refrigerator scored highest in sensory quality with retardation of discoloration and softening.Soluble solid and soluble sugar content decreased over time as did the amount of titratable acidity.Weight loss of fruit was reduced tremendously by refrigerator combined with CPP.Fruits almost developed soft flesh on first day at 20℃,by this time,fruits at refrigerator successfully overcame the problem and extended the period before the fruits became over-soft.To sum up,the suitable cold chain method of peach fruit was forced-air cooling to 5 ℃,storage at 0 ℃ combined with controlled atmosphere(CA:10% CO2,10% O2)or wraped in CPP,transportation 0℃packaged with CPP,retailing at 0℃with CPP and house preservation in refrigerator at 4℃with CPP. |
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