| Apricot(Prunus armeniaca L.)belongs to the climacteric class of fruits is one of the main fruit crops in the Xinjiang Province China,where it has become a part of the socio-economic life of farming community over the centuries.Fresh apricots have a short shelf-life partly ascribed to a high respiration rate and a rapid ripening proeess.These fruits are also sensitive to microbial spoilage even at storage conditions of low temperature and high relative humidity.Therefore,improved methods for apricots preservation should be developed.This study aimed to evaluate the effect of γ-irradiation and electron beam(EB)treatment on the chemical,sensory,and microbial quality of unsulfured sun-dried apricots during storage to determine the optimum radiation methods and radiation levels at which fruit quality can be well maintained.The packaging methods are also studied to select an optimized package method in this paper.The main contents and results of this investigation were showed as follows:1.The chemical,sensory,and microbial quality of γ-ray and EB just treated unsulfured sun-dried apricots was studied to choose an optimized irradiated method for sun-dried apricots quality maintenance.The sun-dried apricots were treated with 1.0,2.0,3.0,4.0,and 5.0 kGy ofγ-ray and EB,respectively.γ-irradiation(D10 value is 2.47 kGy for the total bacterial count and and 2.59 kGy for yeast and mold count)and EB treatment(D10 value is 2.59 kGy for the total bacterial count and and 3.33 kGy for yeast and mold count)both have significant effects on microbial quality,but there are no significant difference between the two treatment methods.The decrease in L value in γ-ray irradiated samples are worse than and EB treatment samples,which indicated that EB treatment is better than γ-ray to color maintenance.The electron microscope showed that the γ-ray and electron beam irradiation had no significant influence on the structure of dried apricot.VC content was not changed before(16.90±0.12 mg/100g)and after either γ-irradiation(16.56±0.14 mg/100g)or EB treatment(16.73±0.16 mg/100g),and there are no significant differences between the two treatment methods.γ-irradiation was more powerful than EB treatment when it comes to sensory that γ-irradiation have much worse influenee on aprieot flavor than EB treatment.Therefore,EB treatment is a better choice to preserve unsulfured sun-dried apricots.2.The chemical,sensory,and microbial quality parameters of electron beam(EB)-irradiated and non-irradiated sun-dried apricots were periodically evaluated to optimize the EB irradiation of sun-dried apricots for quality maintenance.The sun-dried apricots were treated with 1.0,2.0,3.0,4.0,and 5.0 kGy of EB and subsequently stored at ambient temperature.EB treatment at 1.0 kGy to 3.0 kGy proved to be beneficial for retaining high levels of p-carotene,ascorbic acid,titratable acidity,total sugars,and color without any significant effect on sensory properties.Doses of 1.0 kGy to 3.0 kGy retained the p-carotene content of sun-dried apricots to 8.21%,9.27%,and 10.43%compared with 6.09%in control samples after 10 months of storage.After 10 months of storage,the maximum losses of ascorbic acid were 37.8%in control samples and 35.5%in 3.0 kGy-irradiated samples.Titratable acidity and total sugars were significantly enhanced immediately after 1.0 kGy to 3.0 kGy irradiation treatment,and both parameters showed no significant change after 10 months of storage.Samples subjected to EB treatment at 3.0 kGy maintained a high overall aceeptability of sun-dried apricots.Decreased number of viable microorganisms to below detection limits was observed after 3.0 kGy irradiation,and compared with the control,the logarithmic reductions after 10 months of storage were 0.98 for yeast and mold count,as well as 1.91 for bacterial count.Therefore,EB irradiation processing at 3.0 kGy proved to be an effective post-harvest treatment for the quality maintenance of sun-dried apricots.3.The effect of general packaging,vacuum packaging,and modified atmosphere packaging(80%CO2+20%N2 and 40%CO2+60%N2)on the chemical,sensory,and microbial quality of unsulfiured sun-dried aprieots during storage was studied to select an optimized package method.Modified atmosphere packaging is better in moisture content maintenance than vacuum packaging and general packaging.All the packaging methods proved to be beneficial for retaining high levels of total sugars.After 10 months of storage,the losses of ascorbic acid in vacuum packaging and general packaging samples are more than modified atmosphere packaging samples.The maximum losses of ascorbic acid were 37.3%in general packaging samples and 28.4%in vacuum packaging samples after 10 months of storage compared with 27.0%and 27.2%in modified atmosphere packaging samples.Modified atmosphere packaging are also better in retaining high levels of VC and p-carotene without any significant effect on sensory properties than general packaging and vacuum packaging.Decreased number of viable microorganisms to below detection limits was observed in modified atmosphere packaging samples after 10 months of storage.Therefore,modified atmosphere packaging(80%CO2+20%N2)proved to be an effective post-harvest treatment for the quality maintenance of sun-dried apricots. |
PDF Full Text Request