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In order to select the varieties suitable for processing blueberry crispy, the quality evaluation of freeze-dried blueberry crispy was carried out. In this study, eight Highbush blueberries and Rabbiteye blueberries varieties in Jiangsu Province were used as raw materials, and were prepared as blueberry crispy by vacuum freeze-drying, and 18 quality indexes such as water content, total sugar, scavenging ability of DPPH free radical, hardness, etc, were determined, and the quality of the blueberry crispy was comprehensively evaluated by principal component analysis. The results showed that the coefficients of variation of sugar-acid ratio and total acid of different varieties of blueberry crispy were larger, with the value of 57.89% and 40.25%, respectively. Principal component analysis showed that the glucose content, anthocyanoside content, total flavonoid content, total antioxidant activity of AEAC, moisture content of dry samples, output rate and hardness were determined as representative indexes for the evaluation of the quality of blueberry brittle grains. Then, the comprehensive quality evaluation model was established. Based on the comprehensive quality score of each variety, the top three blueberry varieties were Legacy, Brightwell and Climax, and the others varieties had negative scores. This indicated that these three kinds of blueberries were more suitable for dry processing as blueberry crispy, among which the Legacy variety was the better. The results of the study provide a basis for the screening and quality analysis of blueberry varieties for dry processing.

To investigate the effects of different microwave drying conditions on the texture and nutritional quality of candied strawberries in a vacuum environment. This study investigated the effects of three different vacuum microwave treatment conditions (2.5 w/g-1.5 h, 3.5 w/g-1 h, 4.5 w/g-0.5 h) on moisture migration characteristics, texture, microstructure, color, anthocyanins, and phenolics of candied strawberries, which were evaluated by hot air drying. The results showed that the time required for vacuum microwave drying to dry candied strawberries to 20%±2% moisture content was significantly lower than that of hot air, and the higher the microwave power, the shorter the drying time. In addition, the water in the candied strawberries obtained after drying mainly appeared in two states, namely, bound water and water not easy to flow. The relaxation time T2 of strawberry candied strawberries obtained by vacuum microwave drying increased with the increase of microwave power, which indicated that the degree of freedom of water increased. Cross-sectional microscopic observation found that vacuum microwave drying caused cell wall rupture, and the higher the microwave power, the closer the site of fissure formation to the medullary core, and the bigger the fissure, and the smaller the porosity, whereas the cellular integrity and the porosity of the samples dried by the hot air were higher than that of microwave drying. In addition, the hardness, viscosity, and a* value of vacuum microwave-dried dried strawberry preserves were lower than those of hot air-dried samples, but the L* value, total sugar, anthocyanin, and phenolic content were higher. In conclusion, vacuum microwave drying had higher drying efficiency and could better retain the nutrients such as anthocyanins in candied strawberries.

The purpose of this study was to discover the quality properties of the commercially available candied strawberries. Fifteen samples with different brands were purchased, and the physicochemical parametes, such as color, texture, sugar and acid content were determined using colorimeter, texture analyzer and HPLC. In addition, sensory scores were evaluated using intensity scale method. The results showed that the moisture content of these preserved strawberries were between 12.49% and 23.86%, and the colorimetric values distribution ranges of L*, a* and b* were 23.25~34.39, 5.17~19.83, and 5.78~17.04, respectively. For the texture characters, there were significant differences (P

In order to clarify the content and structural changes of different pectin fractions in grape cell walls under ultrasonic treatment, the grapes were treated with different ultrasonic time and ultrasonic power in this study, and the content of pectin fractions, composition of monosaccharides and structural changes of grape cell walls were analyzed by means of carbazole sulfuric acid method, PMP pre-column derivatization, high-performance liquid gel chromatography , scanning electron microscopy, Fourier transform infrared spectroscopy and circular dichroism. Results showed that the highest and the lowest contents in fresh grape cell walls were alkali-soluble pectin (NSP) and chelate pectin (CSP), respectively, and they were 27.41 mg/g AIR and 8.25 mg/g AIR. The total pectin decreased after ultrasonic treatments, in which the water-soluble pectin (WSP) increased and the CSP and NSP decreased. A total of six monosaccharides were detected in three pectins, and the monosaccharides of different pectin were not the same. The galactose and arabinose were high in WSP, the glucuronic acid was the most abundant of CSP and the rhamnose were the highest in NSP. After ultrasonic treatment, the contents of monosaccharides decreased, while the composition did not change, and the main chain structure of pectin was no change, but the linear structure and the degree of branch chain were changed. With the increase of ultrasonic times and powers, the molecular weight of different pectins declined gradually. And in the microstructure showed a more loose morphology. In addition, ultrasonic treatment had an effect on the structure and chain conformation of CSP and NSP, which made their maximum response values shift, and the effect of ultrasonic power was more significant. In conclusion, ultrasonic treatment could reduce the pectin and monosaccharide contents in grape cell walls, and affect the molecular linear structure and molecular chain conformation of pectin. These results can provide theoretical basis for the quality change of grape products under ultrasonic treatment.

In order to develop nutrient rich personalized food, the effects of different guar gum concentrations on rheological, gelation, 3D printing, microstructural properties and functional groups of purple sweet potato gels were explored by rheological analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The results showed that apparent viscosity, storage modulus, loss modulus, L*, gumminess and chewiness of purple sweet potato gels increased, the micro pore size decreased, and the gel network structure was denser with the increase of guar gum concentration. The water holding capacity of purple sweet potato gels was 80.49% and the gel strength was 72.67 g when guar gum concentration was 1.6%. The addition of guar gum significantly improved 3D printability of purple sweet potato gels. When guar gum was added at 1.2% and 1.6%, 3D printed purple sweet potato gels had good formability, the average accuracy deviation was less than 1%, and the stability deviation was less than 5% after 6 hours of storage. The addition of guar gum would not produce new functional groups in 3D printed purple sweet potato gels, but mainly strengthened interactions of CH2 bonds and O-H bonds. This study provided a theoretical basis for the development of 3D printing of plant-based ingredients, which was very important for the personalization of functional foods.

In order to discover the moisture distribution and migration during the drying process of strawberries at constant or gradient temperatures and the effect on the quality of dried strawberries, the strawberries which had experienced osmotic dehydration were dried under constant temperatures (60 °C-12 h, flip it over when dry to 6 h) and gradient temperature (65 °C-2 h, 60 °C-2 h, 55 °C-2 h, flip it over, 65 °C-2 h，60 °C-2 h，55 °C-2 h) during hot air drying. Low-field nuclear magnetic resonance (LF-NMR) was used and the physicochemical (texture, VC, total phenols) and sensory qualities (flavor, texture, taste, color) of the preserved strawberries obtained by the two drying programs were compared. The results showed that the water content of the dry base of strawberries at both programs decreased with time extending gradually, but the rate of gradient temperature was higher than that of constant temperature drying. From the T2 inversion spectra and peak areas of LF-NMR, it illustrated that the free water was the main form of water in the osmotically dehydrated strawberries, and there were also a small amount of bound water and immobile water. With the drying procedure proceeded, the T2 peak of the strawberry gradually decreases, which indicates a decrease in the mobility of the water. However, the total relaxation peak area of constant temperature drying and gradient drying was reduced to 31.3% and 26.4% of the original at the end of the drying programs, which showed that the gradient drying had higher drying efficiency. Magnetic resonance imaging (MRI) showed that the water in strawberries was firstly enriched to the broken tip of the fruit and dispersed, then in the medium of the drying process, the peel took the main position for the water evaporation, and finally some water left in the pith. From the imaging results, the main difference between the two drying programs was that there was an obvious homogeneous wetness phenomenon in the strawberries after 6 h drying i.e. the water was redistributed evenly in the fruit at that time, while this process did not appeared in the gradient drying. In addition, the VC and total phenolic contents of dried strawberries were significantly higher (P

Plasma-activated water (PAW) treatment is an effective technique for the quality retention of fresh vegetables with cold atmospheric plasma using controllable parameters. This study investigated the effect of PAW on the postharvest quality of shepherd’s purse (Capsella bursa-pastoris). The results displayed that PAW treatment with an activation time of 5, 10, 15, and 20 min reduced the yellowing rate and weight loss of the shepherd’s purse during 9 days of storage. Compared with untreated samples, PAW treatment at different times reduced the number of total bacteria, coliform, yeast, and mold by 0.18–0.94, 0.59–0.97, 0.90–1.18, and 1.03–1.17 Log CFU/g after 9 days of storage, respectively. Additionally, the treatments with PAW-5 and PAW-10 better preserved ascorbic acid, chlorophyll, total phenol, and total flavonoid contents. They also maintained the higher antioxidant and CAT activity and inhibited the formation of terpenes, alcohols, and nitrogen oxide compounds of the shepherd’s purse at the end of storage. The microstructural result illustrated that the cells of the shepherd’s purse treated with PAW-5 and PAW-10 were relatively intact, with a small intercellular space after storage. This study demonstrated that PAW treatment effectively improved the postharvest quality of shepherd’s purse.

In order to compare the differences in dehydration efficiency and quality of mango under different osmotic methods in summer (30 ℃) and winter (20 ℃) production environments, this paper explored the effects of SSD and LOD on the dehydration efficiency and quality of sugar-stained mango by taking the water loss rate, solid gain rate, effective diffusion coefficient of water, diffusion coefficient of soluble solids, retention rate of VC and total phenols, and tri-state water conversion as the indexes. The results showed that the dehydration efficiency and nutrient retention rate of solid osmotic were higher than those of liquid osmotic. After 48 h of sugaring, the maximum water loss rate and solid gain rate of SSD40 (sucrose:mangos (w/w) 4:10) were 49% and 5.11% at ambient temperature of 20 ℃, and the retention rates of VC and total phenols of SSD20 (sucrose:mangos (w/w) 2:10) were 47.43% and 43.66%. At ambient temperature of 30 ℃, the maximum water loss rate and solid gIain rate of SSD40 were 57.41% and 6.36%, and the maximum retention rates of VC and total phenols of SSD20 were 43.79% and 42.43%. The permeation process changed the binding state of water in mango samples, and the water with high degree of freedom migrated to the direction of low degree of freedom. The results of this study will provide a theoretical reference for the application of solid penetrating pretreatment technology for dried fruit products.

In order to explore the water diffusion characteristics of green bananas during the microwave drying process, a microwave drying test was conducted to investigate the green bananas drying characteristics under different microwave power densities (3, 5, 7 and 9 W/g), and the microwave drying test model of green bananas was established. Low-field nuclear magnetic resonance (LF-NMR) was used to investigate the internal moisture distribution and change law of green bananas during the drying process. Results showed that drying rate of green bananas in the microwave drying process increased first and then decreased, the effective diffusion coefficient was between 1.082×10−8 and 7.708×10−8 m2/s, and also increased with the increasing of microwave power density. The nuclear magnetic resonance experiments showed that, during the drying process, the free water was removed first, the non-flowing water showed an overall upward trend and then a downward trend, while the combined water showed an overall upward trend. With the extension of microwave drying time, the water peak area of the three states decreased and the total peak moved in the direction of the decrease of relaxation time, at the end of drying, the free water in green banana was basically removed, and the internal water mainly existed in the state of combined water and non flowing water. By fitting green banana drying kinetics model, it was found that the Page model fitted best (R2>0.9), which could provide a basis for effectively describing the variation law of water with time during the microwave drying process of green bananas.

This study aimed to explore the effect of osmotic methods on the cell structure and quality of freeze-dried mango. This experiment uses jade as the raw material, mango was treated by solid osmotic (SSD) and liquid osmotic (LOD) at 20 and 30 ℃, and then vacuum freeze-dried. By measuring the soluble solids and cell morphology of fresh mango samples after osmosis treatment, and analyzing the changes of elastic modulus, porosity, cell wall structure, color and VC, total phenols, and β-carotene retention index of freeze-dried mangoes. The results showed that the increasing of soluble solids in solid osmotic mango was higher than that in liquid osmotic. There was no significant difference between the cell morphology of liquid osmotic mango and fresh sample (CK). The content of soluble solids and the shrinkage degree of cell morphology increased with the increasing of sucrose, the solid osmotic reduced the intercellular porosity and increased the elastic modulus of mango. Moreover, results of infrared spectroscopy showed that the stretching vibration absorption peak of O-H increased with the increasing of sucrose content. Low sucrose solid osmotic helps to maintain the color of mango. The retention rates of VC and total phenol in solid osmotic were higher than those in liquid osmotic at ambient temperature of 20 and 30 ℃, and the highest retention rates of SSD20 VC and total phenol in solid state infiltration were 37.75% and 33.37%, respectively. The retention rate of β-carotene in vacuum freeze-dried mango SSD20 treated with solid osmotic treatment was higher than that of liquid osmotic treatment LOD30, but the retention rate of β-carotene decreases gradually with the increasing of sucrose supplementation in solid osmotic treatment. The results of this study showed that low sucrose solid osmotic could effectively improve the comprehensive quality of vacuum freeze-dried mango, which would provide a theoretical reference for improving the quality of dried mango products.

The mechanism behind the sterilization effects of ozone in combination with sodium metasilicate (SM) is still unknown. Therefore, the effects of treatments of fresh-cut cabbage with aqueous ozone combined with SM on microbial growth, and produce quality were evaluated in detail during storage. The results indicated that treating the cabbage with 2 ppm aqueous ozone combined with 0.4% SM for 2 min achieved acceptable microbial quality, and reduced E. coli O157:H7 counts by 3.33 logs compared with the control samples after 12 d of storage. This combination treatment had no negative effects on sensory characteristics (appearance and off-odor), color, and the contents of vitamin C, total phenols and carotenoids. The combined ozone-SM treatment was more effective than individual treatments in controlling the pathogens and native microorganisms on fresh produce and could extend the storage up to 12 d. This hurdle treatment may be used as a processing intervention to control microorganism.

Flavonoids can influence the bioaccessibility of carotenoids. In this study, the effect of citrus flavanones on β-carotene (Bc) bioaccessibility, lipid lipolysis and Bc micellarization were investigated. The results show that citrus flavanones significantly increased the bioaccessibility of Bc, made it from 15.85% to 19.67% (p