Discoloration investigations of freeze-dried carrot cylinders from physical structure and color-related chemical compositions.

BACKGROUND: High carotenoid content always lead to a yellower/redder color in carrots, while a puzzling phenomenon still exists that freeze-dried carrots (FDC) have a higher carotenoid content but a lighter color compared with thermal-dried carrots. It seems that carotenoid is not the only main factor affecting sample color. Hence the discoloration characteristics of freeze-dried carrots were comprehensively analyzed from physical structure and color-related chemical composition profile. RESULTS: Outcomes of low-field nuclear magnetic resonance and scanning electron microscopy showed that sublimation of immobilized water preserved the intact porous structure of FDC, which kept the volume shrinkage below 30% and led to less accumulations of color-related compositions. Besides, results of correlation and principal component analysis-X model proved that lutein and caffeic acid mainly affected a* value (r = 0.917) and b* value (r = 0.836) of FDC, respectively. Moreover, lipoxygenase indirectly affected sample color by degrading carotenoids, and the lutein content loss for fresh and blanching FDC was 41.56% and 47.14%, respectively. CONCLUSIONS: The discoloration of FDC was significantly affected by both physical structure and color-related chemical compositions. © 2021 Society of Chemical Industry.

Effect of the moisture equilibrium process on the expansion behavior of instant controlled pressure drop (DIC) drying of dried apple cubes.

BACKGROUND: Recently, consumers' demand on high quality dried fruit or vegetable products have increased dramatically. The instant controlled pressure drop (DIC) dried products have attracted consumers' attention due to its unique sensory characteristics. The product quality, especially the appearance quality of the DIC products, is influenced closely by water status and water distribution in the material, which is rarely reported in the literatures. In this study, a comparison system for the apple cubes with or without the moisture equilibrium process (MEP) was established to explain the effect of the MEP on the expansion behavior of the DIC dried apple cube. RESULTS: The results showed that the MEP could induce a more homogenous spatial distribution of water in the semi-dried apple cube after pre-drying. Meanwhile, the MEP treated and DIC dried apple cubes showed better quality in terms of the appearance and texture properties including high porosity (71.77%), large pores (maximum pore size of 1.55 mm), and thin pore walls (pore wall thickness of 0.079 mm). CONCLUSION: The MEP was approved to be a compulsory treatment to achieve the DIC dried apple cubes with good expansion behavior. © 2019 Society of Chemical Industry.

Apple juice concentrate impregnation enhances nutritional and textural attributes of the instant controlled pressure drop (DIC)-dried carrot chips.

BACKGROUND: Osmotic pretreatment is an effective processing unit for improving the textural quality of dried fruit and vegetable snacks, whereas nutrition loss and high calorie after impregnation is still a noteworthy shortcoming of sugar-immersed products. Therefore, the use of apple juice concentrate as a clean label solution to improve the qualities of instant controlled pressure drop (DIC)-dried carrot chips was investigated. RESULTS: Apple juice concentrate impregnation substantially enhanced the physical properties of the carrot chips, including hardness (38.28 N), crispness (2.01 mm), porosity (66.72%) and homogeneous microstructure, comparable to chips obtained using sucrose and maltiltol based osmotic solutions. Additionally, compared to the sucrose and maltiltol impregnated chips, a higher retention of carotenoids (302.81 µg g-1 , dry basis), a higher multiplicity of phenolic compounds, stronger antioxidant activities and a superior sensory score were observed in the chips pretreated with apple juice concentrate. CONCLUSION: Apple juice concentrate could be used as a clean label osmotic solution to enhance the organoleptic attributes and fortify the nutritional properties of DIC-dried carrot snacks. © 2019 Society of Chemical Industry.

Determination of phenolic compounds and antioxidant activities from peel, flesh, seed of guava (Psidium guajava L.).

White-flesh guava is widely planted in tropical or subtropical areas of Southeast Asia. Despite of folk statements on specific function, few researches are focused on the description of its plant secondary metabolites. In the present work, contents of total phenolics and flavonoids as well as antioxidant activity from different parts (peel, flesh, and seed) were determined. The constituents of ethanol extracts were characterized by HPLC-QTOF-MS. A total of 69 phenolic compounds as well as nine polar compounds were detected, with flavonoids, hydrolyzable tannins, phenolic acid derivatives, and benzophenones of the four predominant phenolic compounds. Moreover, the presence of other phenolics (lignan, phenylethanoid, stilbenoid, and dihydrochalcones) was revealed. Simultaneously, the polar compounds, such as triterpenoids, iridoid were identified. Benzophenones and triterpenoids were proved to be marked constitutes of peel and flesh, respectively. The existence of isoflavonoids, lignan, phenylethanoid were firstly reported for edible parts or by-products of guava. The results showed that white-flesh guavas, particularly peel parts, were superior resources of antioxidant compounds, with exploitation value.

Kinetic modelling of non-enzymatic browning and changes of physio-chemical parameters of peach juice during storage.

Kinetics of non-enzymatic browning and loss of free amino acids during different storage temperature (4, 25, 37 °C) were investigated. Changes of browning degree (A420), color parameters, Vitamin C (Vc), free amino acids and 5-hydroxymethylfurfural (5-HMF) were analyzed to evaluate the non-enzymatic browning reactions, which were significantly affected by storage temperature. The lower temperature (4 °C) decreased the loss of Vc and the generation of 5-HMF, but induce the highest loss of serine. At the end of storage, loss of serine, alanine and aspartic acid were mainly lost. Results showed that zero-order kinetic model (R2 > 0.859), the first-order model (R2 > 0.926) and the combined kinetic model (R2 > 0.916) were the most appropriate to describe the changes of a* and b* values, the degradation of Vc and the changes of A420, L* and 5-HMF during different storage temperatures. These kinetic models can be applied for predicting and minimizing the non-enzymatic browning of fresh peach juice during storage.

Evaluation of browning ratio in an image analysis of apple slices at different stages of instant controlled pressure drop-assisted hot-air drying (AD-DIC).

BACKGROUND: Computer vision-based image analysis systems are widely used in food processing to evaluate quality changes. They are able to objectively measure the surface colour of various products since, providing some obvious advantages with their objectivity and quantitative capabilities. In this study, a computer vision-based image analysis system was used to investigate the colour changes of apple slices dried by instant controlled pressure drop-assisted hot air drying (AD-DIC). RESULTS: The CIE L* value and polyphenol oxidase activity in apple slices decreased during the entire drying process, whereas other colour indexes, including CIE a*, b*, ΔE and C* values, increased. The browning ratio calculated by image analysis increased during the drying process, and a sharp increment was observed for the DIC process. The change in 5-hydroxymethylfurfural (5-HMF) and fluorescent compounds (FIC) showed the same trend with browning ratio due to Maillard reaction. Moreover, the concentrations of 5-HMF and FIC both had a good quadratic correlation (R2 > 0.998) with the browning ratio. CONCLUSION: Browning ratio was a reliable indicator of 5-HMF and FIC changes in apple slices during drying. The image analysis system could be used to monitor colour changes, 5-HMF and FIC in dehydrated apple slices during the AD-DIC process. © 2016 Society of Chemical Industry.

Characterization of Chinese white-flesh peach cultivars based on principle component and cluster analysis.

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.

Comparison of different drying methods on the physical properties, bioactive compounds and antioxidant activity of raspberry powders.

BACKGROUND: Dehydration has been considered as one of the traditional but most effective techniques for perishable fruits. Raspberry powders obtained after dehydration can be added as ingredients into food formulations such as bakery and dairy products. In this study, raspberry powders obtained by hot air drying (HAD), infrared radiation drying (IRD), hot air and explosion puffing drying (HA-EPD), infrared radiation and microwave vacuum drying (IR-MVD) and freeze drying (FD) were compared on physical properties, bioactive compounds and antioxidant activity. RESULTS: Drying techniques affected the physical properties, bioactive compounds and antioxidant activity of raspberry powders greatly. FD led to significantly higher (P < 0.05) values of water solubility (45.26%), soluble solid (63.46%), hygroscopicity (18.06%), color parameters and anthocyanin retention (60.70%) of raspberry powder compared with other drying methods. However, thermal drying techniques, especially combined drying methods, were superior to FD in final total polyphenol content, total flavonoid content and antioxidant activity. The combined drying methods, especially IR-MVD, showed the highest total polyphenol content (123.22 g GAE kg(-1) dw) and total flavonoid content (0.30 g CAE kg(-1) dw). Additionally, IR-MVD performed better in antioxidant activity retention. CONCLUSION: Overall, combined drying methods, especially IR-MVD, were found to result in better quality of raspberry powders among the thermal drying techniques. IR-MVD could be recommended for use in the drying industry because of its advantages in time saving and nutrient retention.

Effect of different drying technologies on drying characteristics and quality of red pepper (Capsicum frutescens L.): a comparative study.

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.

Influence of pre-drying treatments on physicochemical and organoleptic properties of explosion puff dried jackfruit chips.

The effects of hot air drying (AD), freeze drying (FD), infrared drying (IR), microwave drying (MV), vacuum drying (VD) as pre-drying treatments for explosion puff drying (EPD) on qualities of jackfruit chips were studied. The lowest total color differences (∆E) were found in the FD-, MV- and VD-EPD dried chips. Volume expansion effect (9.2 %) was only observed in the FD-EPD dried chips, which corresponded to its well expanded honeycomb microstructures and high rehydration rate. Compared with AD-, IR-, MV- and VD-EPD, the FD-EPD dried fruit chips exhibited lower hardness and higher crispness, indicative of a crispier texture. FD-EPD dried fruits also obtained high retentions of ascorbic acid, phenolics and carotenoids compared with that of the other puffed products. The results of sensory evaluation suggested that the FD-EPD was a more beneficial combination because it enhanced the overall qualities of jackfruit chips. In conclusion, the FD-EPD could be used as a novel combination drying method for processing valuable and/or high quality fruit chips.

Quality evaluation of yellow peach chips prepared by explosion puffing drying.

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).

Clinical gait analysis in older children with autism spectrum disorder.

Individuals with autism spectrum disorder (ASD) often exhibit motor deficits that increase their risk of falls. There is a lack of understanding regarding gait biomechanics demonstrated by older children with ASD. The purpose of the study was to determine differences in gait patterns between older children with ASD and typically developing children. Eleven children with ASD and 11 age- and gender-matched typically developing children were recruited for the study. Participants walked on a force-instrumented treadmill at a constant speed (1.1 â€‹m/s â€‹- â€‹1.2 â€‹m/s) for five minutes (min). Participants performed maximal voluntary contractions to assess their knee muscular strength. Differences between individuals with ASD and matched control participants were examined through paired t-tests with a significance level of p â€‹≤ â€‹0.05. Individuals with ASD demonstrated a smaller knee extensor torque compared to controls (p â€‹= â€‹0.002). Participants with ASD exhibited a shorter stride length (p â€‹= â€‹0.04), a greater cadence (p â€‹= â€‹0.03), and a higher variation in stride width (p â€‹= â€‹0.04) compared to control participants. The individuals with ASD experienced a greater braking ground reaction force (p â€‹= â€‹0.03) during loading response. The results indicate older children with ASD develop a unique gait pattern signified by a reduced stride length, increased cadence, and an increase of variation in stride width. This unique gait pattern may represent a movement strategy used by the individuals with ASD to compensate for the weakness associated with their knee extensor muscles. Individuals with ASD who demonstrate these unique gait deviations may face reduced postural stability and an increased risk of fall-related injuries.

Effect of osmotic dehydration combined with vacuum freeze-drying treatment on characteristic aroma components of peach slices.

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.

Word concreteness modulates bilingual language control during reading comprehension.

Controversies persist in the literature regarding the existence of bilingual language control during comprehension, which may be attributed to overlooking the modulating effect of word concreteness. To test this hypothesis, we conducted an experiment using abstract and concrete words, thereby manipulating the activation level of the nontarget language. Sixty Chinese-English bilinguals were instructed to switch between two languages in word reading tasks. We found that abstract words (e.g., [correct], wrong) did not show switching costs, indicating no additional time for switching between languages compared to repeating the same language. In contrast, concrete words (e.g., [sunny], rainy) elicited significant larger switching costs. These findings might suggest greater language control demands on the nontarget language when reading more concrete words. This study offers insights into the modulating effect of word concreteness in language processing on bilingual language control during reading comprehension. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Understanding the impact of pectin on browning of polyphenol oxidation system in thermal and storage processing.

Browning of some processed fruit products was affected not only by polyphenol oxidation but also by cell wall polysaccharides (pectin). The study was performed to understand the mechanism of browning in the pectin system. The catechin/chlorogenic acid oxidation system in three pectins significantly enhanced their browning during thermal storage with pectin structure- and concentration-dependent. Particularly, the structural and physicochemical properties of pectin were examined to determine its effects on the kinetics of polyphenol oxidation and the stability of free polyphenols. Moreover, pectin impacted the fluorescence characteristics of polyphenols by cross-linking with the aromatic ring of polyphenols. In turn, the interaction between polyphenols and pectin impacted the chemical bond vibration of pectin, thereby affecting its optical features and browning. The correlation analysis revealed that the monosaccharide composition, Ratio 1, Ratio 2, Ratio 3, methyl esterification, ζ-potential, and polydispersity index of pectin were significantly correlated with the browning of the pectin-polyphenol oxidation system.

Influence of different pre-treatments on flavor quality of freeze-dried carrots mediated by carotenoids and metabolites during 120-day storage.

Changes in carotenoids and volatiles (including ß-carotene-metabolites) of freeze-dried carrots (FDC) treated by thermal/nonthermal-ultrasound (40 KHz, 10 min) and ascorbic (2%, w/v)-CaCl2 (1%, w/v) solution ((H)UAA-CaCl2) during a 120-day storage period were investigated. The results of HS-SPME/GC-MS showed that caryophyllene was the dominant volatile compound (70.80-275.74 µg/g, d.b) in FDC, and 144 volatile compounds were detected in 6 samples. Besides, 23 volatile compounds were significantly correlated with ß-carotene content (p < 0.05), and ß-carotene degraded to off-flavor compounds (ß-ionone: 22.85-117.26 µg/g, ß-cyclocitral: 0-113.84 µg/g and dihydroactindiolide: 4.04-128.37 µg/g) that had adverse effects on FDC flavor. However, UAA-CaCl2 effectively preserved the total carotenoid content (793.37 µg/g), and HUAA-CaCl2 reduced the off-odors (such as ß-cyclocitral and isothymol) formation at the end of storage. These results indicated that (H)UAA-CaCl2 treatments were conducive to the maintenance of carotenoids and the flavor quality of FDC.

Effects of cell morphology on the textural attributes of fruit cubes in freeze-drying: Apples, strawberries, and mangoes as examples.

The influence of cell morphology on the textural characteristic of freeze-dried apple, strawberry, and mango cubes was evaluated. Corresponding restructured cube samples without intact cell morphology were prepared as controls. Results indicated that the presence of cell morphology strengthened the shrinkage and collapse of samples during freeze-drying, especially in mangoes due to the high content of sugar. Intact cell morphology was found in natural fruit cubes after freeze-drying by scanning electron microscopy (SEM) observation, making them exhibit a more regular microporous structure, further resulting in higher hardness than the restructured cubes. However, the intact cell morphology negatively affected the crispness of freeze-dried cubes since it enhanced structural collapse. The freeze-dried samples without cell morphology would destroy the cellulose structure and form a continuous open-pore structure under the concentration effect of ice crystals during freezing, which accelerates the escape of water molecules, increases the drying rate, and avoid collapse. Sensory experiments found that restructured cubes without intact cell morphology exhibited greater comprehensive acceptance, suggesting the potential application of cell morphology disruption in the future freeze-drying industry.

Effect of osmotic dehydration with different osmosis agents on water status, texture properties, sugars, and total carotenoid of dehydrated yellow peach slices.

The water status, texture properties, sugars, and total carotenoid of dehydrated yellow peach slices pretreated with or without osmotic dehydration (OD) combined with heat pump drying were studied. In this study, different osmotic agents were used, namely, sucrose and isomaltooligosaccharide (IMO) with 30 °Brix for 1, 3, and 5 h. Results showed that the dehydrated samples pretreated by sucrose-OD with the best shape and cell structure showed lower hardness compared to the dehydrated yellow peach slices with IMO-OD pretreatment and without OD pretreatment. Notably, the highest total carotenoid content was found in dehydrated yellow peach slices pretreated by IMO-OD, followed by samples without OD, and samples with sucrose-OD pretreatment. In addition, the lowest aW (0.517) was obtained in samples with IMO-OD for 5 h, which was beneficial for storage. The assessment of water status and total carotenoid content of dehydrated yellow peach slices showed that IMO-OD pretreatment could better improve the quality of dehydrated fruits. Moreover, the use of IMO in OD treatment was a good alternative to sucrose.

Novel insight into the evolution of volatile compounds during dynamic freeze-drying of Ziziphus jujuba cv. Huizao based on GC-MS combined with multivariate data analysis.

To understand the evolution of aroma in jujubes during dynamic freeze drying (FD), the relationship between aroma compounds, precursors, and related enzyme activities were analyzed. Fifty-three volatiles were identified during FD processing. After FD, the total aroma contents were increased from 11,004 to 14,603 µg/kg, ketones content was significantly decreased by 54.11 %, resulted in the loss of creamy note in freeze-dried jujube (FDJ). Through the network analysis, serine, glycine, proline, valine, cysteine, arginine, glutamic acid, lysine and leucine had the significant correlation with pyrazines, dominated the roasty note of FDJ. Linoleic acid, α-linolenic acid and oleic acid with lipoxygenase had important effects on the increase of esters (from 412 to 9,486 µg/kg), contributed fruity and sweet notes of FDJ. Besides, through the Mantel test, the influence degree of factors on the formation of FDJ aroma was ranked as temperature > enzyme activity > fatty acids > amino acids.

New insight into pectic fractions of cell wall: Impact of extraction on pectin structure and in vitro gut fermentation.

Pectic polysaccharides modulate gut fermentation ability, which is determined by structural characteristics. In this work, apple pectins were extracted by HCl (HAEP), NaOH (AEP), cellulase (EAEP), and in parallel cell wall pectic fractions were sequentially extracted by water (WEP), chelator (CEP) and NaOH (NEP). The aim is to comprehensively compare the impact of extraction on pectin structure and gut fermentation behavior. Results showed that high content of galacturonic acid (90.65 mol%) and large molecular weight (675 kg/mol) were detected in the HAEP. Molecular morphology of the HAEP presented high linearity, while AEP, EAEP and WEP exhibited compact filamentous structures with highly branched patterns. The AEP was characterized by high yield (33.1 g/100 g d.b.), moderate molecular weight (304 kg/mol) and large extent of rhamnogalacturonan-I region (24.88 %) with low degree of branching (1.77). After in vitro simulated gut fermentation for 24 h, total content of short-chain fatty acid (SCFA) generated with the AEP supplement increased to 36.8 mmol/L, followed by EAEP, HAEP and WEP (25.2, 24.2 and 20.3 mmol/L, respectively). Meanwhile, WEP simultaneously produced the highest ammonia content (22.4 mmol/L). This investigation suggests that the fermentation of AEP produces more beneficial SCFA and less ammonia, thus indicating a better gut fermentation property.