ABSTRACT
Hot air drying (HD), vacuum freeze drying (FD), and pilot-scale freeze drying (PSFD) are extensively used to prepare peach slices. However, the aroma of hot air drying and vacuum freeze-drying is yet to be addressed. In this study, HS-SPME-GC-MS was used to characterize and quantify the volatile compounds in peach slices. First, 33, 36, and 46 volatile compounds were identified and quantified in the HD, FD, and PSFD groups, respectively. PSFD is preferable to HD and FD in terms of the volatile compound types, content, and aroma profiles. PSFD was selected for subsequent permeation and dehydration experiments. The key aroma compounds with an OAV ≥ 1 were found in the PSFD30 group. GC-O analysis was conducted on the PSFD30 group, leading to the preliminary identification of 2-methylbutanal, pentanal, hexanal, 2-hexenal, phenylacetaldehyde, ethyl acetate, 2-methylbutyl acetate, ethyl lactate, linalool, methyl heptenone, and γ-octalactone as distinctive aromas in dried peach slices.
ABSTRACT
The purpose of this study was to gain insights into the variations in quality characteristics of white-flesh peach fruits. Eighteen cultivars of north of China were investigated. The quality evaluation indicators, including color, physico-chemical and nutritional attributes were measured. Analysis of variance revealed that all the indicators showed significant differences among the cultivars, except edible rate. Principal Component Analysis (PCA) conducted to distinguish the indicators among cultivars, suggested that the most important factors affecting the peach quality could be reduced into nine principal components. Crude fiber content, glucose content, peel-b*, TA, moisture content, pulp-firmness, quinic content, shikimic content and edible rate could be regarded as the characteristic indicators for PC1, PC2, PC3,PC4, PC5, PC6, PC7, PC8 and PC9, respectively. Cluster analysis classified the different cultivars into five main groups on the basis of the measured quality evaluation indicators, and the results were in good accordance with PCA results.
ABSTRACT
BACKGROUND: Hot air drying and sun drying are traditional drying technologies widely used in the drying of agricultural products for a long time, but usually recognized as time-consuming or producing lower-quality products. Infrared drying is a rather effective drying technology that has advantages over traditional drying technologies. Thus, in order to investigate the application of infrared drying in the dehydration of red pepper, the drying characteristics and quality of infrared-dried red pepper were compared with those of sun-dried and hot air-dried red pepper. RESULTS: The infrared drying technology significantly enhanced the drying rate when compared with hot air drying and sun drying. Temperature was the most important factor affecting the moisture transfer during the process of infrared drying as well as hot air drying. Effective moisture diffusivity (Deff ) values of infrared drying ranged from 1.58 × 10(-9) to 3.78 × 10(-9) m(2) s(-1) . The Ea values of infrared drying and hot air drying were 42.67 and 44.48 kJ mol(-1) respectively. Infrared drying and hot air drying produced color loss to a similar extent. Relatively higher crispness values were observed for infrared-dried samples. CONCLUSION: Sun drying produced dried red pepper with the best color when compared with hot air drying and infrared drying. Meanwhile, infrared drying markedly improved the drying rate at the same drying temperature level of hot air drying, and the products obtained had relatively better quality with higher crispness values. © 2015 Society of Chemical Industry.
Subject(s)
Capsicum/chemistry , Desiccation/methods , Food Preservation/methods , Infrared Rays , Color , Fruit , Hot Temperature , SunlightABSTRACT
Nineteen evaluation indicators in 15 yellow peach chips prepared by explosion puffing drying were analyzed, including color, rehydration ratio, texture, and so on. The analysis methods of principle component analysis (PCA), analytic hierarchy process (AHP), K-means cluster (KC) and Discriminate analysis (DA) were used to analyze the comprehensive quality of the yellow peach chips. The dispersed coefficient of variation of the 19 evaluation indicators varied from 3.58 to 852.89 %, suggesting significant differences among yellow peach cultivars. The characteristic evaluation indicators, namely, reducing sugar content, out-put ratio, water content, a value and L value were analyzed by PCA, and their weights 0.0429, 0.1140, 0.4816, 1.1807 and 0.1807 were obtained by AHP. The levels in 15 cultivars effectively were classified by discrimination functions which obtained by KC and DA. The results suggested that three levels of comprehensive quality for yellow peach chips were divided, and the highest synthesis scores was observed in "senggelin" (11.1037), while the lowest synthesis value was found in "goldbaby" (-3.7600).