Instant Controlled Pressure Drop Drying Research Articles

Osmotic dehydration with different agents induced pectin diversity: Physicochemical and structural properties of pectin from instant controlled pressure drop dried peach chips

Pectin as an important cell wall matrix that can be affected by osmotic dehydration (OD) pretreatment, determines the texture characteristics of dried fruit and vegetable products. This study investigated the effect of OD on the structural, thermal and rheological properties of pectin extracted from peach chips prepared by instant controlled pressure drop (DIC) drying. In detail, erythritol, glucose, and trehalose were selected as the osmotic agents (300 g/L). Pectin extracted from Ery-OD samples with a loose structure presented the highest molecular weight (432.9 kDa). The lowest content of arabinose (155.16 mg/g) and galactose (32.80 mg/g) were obtained in Glc-OD samples. With the infiltration of trehalose, the thermal stability of pectin was improved, which contributed to the uniform and complete network structure of pectin. 1H and 13C spectra analysis showed the significant alteration in pectin molecular structure induced by OD pretreatments, which affected the shear thinning behavior of pectin solution. Overall, the type of osmotic agents played a crucial role in the structural, thermal and rheological properties of pectin, which could reflect on the macro-texture characteristics of peach chips. This study would provide a theoretical basis for revealing the effect mechanism of OD on the texture of DIC fruit and vegetable chips at molecular level.

Comparison of characterization and composition of melanoidins from three different dried apple slices

The composition of melanoidins in dried apple that affects quality remains unclear. The composition and structure of melanoidins in dried apple slices by hot air drying (HAAM), instant controlled pressure drop drying (DICAM), and vacuum freeze-drying (FDAM) were investigated. It showed that the melanoidins were highly heterogeneous mixtures with a light-yellow color and blue-green fluorescence, belonging to polysaccharide-type melanoidins. Specifically, HAAM had a large molecular weight (929.5 g/mol) and wide molecular weight distribution, with more double-bond conjugated systems. DICAM (610.9 g/mol), possessing the strongest fluorescence intensity, was mainly composed of compounds with fewer π-conjugated structures and more electron-donating groups. As a control, the low level of Maillard reaction in FDAM resulted in the formation of the smallest molecular weight (458.6 g/mol) with weak fluorescence intensity. Moreover, 10 compounds were tentatively identified in apple melanoidins. This study provides the foundation for the future functional preparation of apple melanoidins.

Instant controlled pressure drop drying: A review on preservation of quality characteristics in fresh produce.

This review describes the efficient Instant controlled pressure drop drying technology. The Détente Instantanée Contôlée (DIC), French for Instant Controlled Pressure-Drop drying, has prodigious potential to cause least variations in the quality characteristics of the final dried product. This review article spotlights the principle of DIC with its effect on vitamins (ascorbic acid), bioactive compounds (carotenoids, polyphenols), physicochemical properties (moisture, rehydration capacity, water holding capacity, color, microstructure texture) and sensory properties of fresh produce. DIC is a thermo-mechanical technique accomplished by treating the fresh produce to saturated steam for less time period, which is carried out by an immediate pressure drop to achieve vacuum. This technique also provides reduced drying time, better volume expansion with larger porosity in the final dried product. It leads to a swift vaporization of the water within fresh produce cells. DIC-treated fresh produce are quickly rehydrated and retains sensory and nutrient quality.

Trends in quality assessment and drying methods used for fruits and vegetables

Studies on drying of fruits and vegetables by means of different methods are numerous. This review aims at presenting the most usual quality analyses carried out in dried fruits and vegetables over the last five years along with the most used drying methods. It was prepared based on a search on Scopus database with the term ‘drying fruit vegetables’. Results show that color and microstructure can be preserved, apparent density can be reduced, and high rehydration capacity can be achieved by using mild drying methods like freeze-drying and innovative drying methods like conductive multi-flash drying. Shrinkage and water activity can be minimized by using pretreatments like osmotic dehydration, ultrasound, and pulsed electric fields. Such pretreatments also produce crispy texture, which can also be obtained with the use of hot air drying followed by microwave-vacuum drying. Antioxidant activity, phenolic compounds and vitamin C content can be maximized by using innovative pretreatments like immersion in solutions rich in bioactive compounds and short drying time. Microbial counts can be decreased by using pretreatments like immersion in ethanol, and modified atmosphere packaging. High sensory acceptability can also be achieved by using innovative drying methods, like instant controlled pressure drop drying.

Study on the Rehydration Quality Improvement of shiitake Mushroom by Combined Drying Methods.

The aim of study is to improve the rehydration quality of dried shiitake mushrooms for their instant food manufacturers and fast restaurants. Serial combined drying methods were investigated to achieve this objective: either instant controlled pressure drop drying (DIC) or freeze drying (FD) was used as the treatments for microstructure improvement, and they were applied either before or after an additional drying step at low (35 °C) or high (65 °C) temperatures. Dried mushrooms were assessed for quality indicators like relative volume, rehydration rate, dry matter loss and sensory scores. Microstructure properties were inferred to understand the physical mechanisms of quality changes. Principal component analysis (PCA) was used to cluster treatments and to identify combinations of drying techniques, rendering improved quality. Consequently, it was shown that DIC treatment before hot air drying at 35 °C was shown to be the most promising combined drying method to enhance the rehydration quality, leading to a high volume recovery ratio, low dry matter loss after rehydration, and high rehydration rates. This good performance could be explained by the retention of pore interconnectivity resulting from the slight expansion of porous structure during DIC and the retention of cell membrane integrity.

Study on the mechanism of volume expansion and texture formation of apple cube dried by instant controlled pressure drop drying (DIC)

Abstract In order to control the quality of the DIC dried food products, this study investigated the energy conversion and the expansion force generation mechanism at the instantaneous pressure drop during the DIC treatment. Their effects on the product texture formation were analyzed. The results showed that the instantaneous vaporization of water at the moment of decompression could generated the expansion energy, which caused the expansion of the internal pores of the apple cube. Hence the volume and absolute porosity of the apple cube were increased. In addition, the pore walls of apple cube with the transition moisture content of 1.068 g/g (d.b.) were collapsed after DIC. Furthermore, DIC apple cube products had the optimal volume expansion ratio (2.317 ± 0.310), hardness (139.44 ± 16.52 N) and crispness (90 ± 17) at the transition moisture content of 0.152 ± 0.018 g/g (d.b.).

Effect of pectin osmosis or degradation on the water migration and texture properties of apple cube dried by instant controlled pressure drop drying (DIC)

Hydrolysis by pectinase and pectin osmosis were applied to apple cubes before instant controlled pressure drop (DIC) drying. The water migration in the apple cubes during drying process was studied by low-field NMR. Pectin osmosis for 1 h could increase the galacturonic acid (GalA) content of the apple cubes (the maximum increase was 24%), whereas the GalA content of the apple cubes hydrolyzed by pectinase decreased (the maximum decrease was 49%). In addition, the moisture migration inside the apple cubes during drying can be hindered by osmosis treatment, but it could be accelerated by short-time pectinase hydrolysis. Besides, the hardness and crispness of apple cubes which were osmosed by pectin was higher (the maximum was 106 ± 13 N, and 53 ± 8 respectively) than that apple cubes hydrolyzed by pectinase (the maximum was 38 ± 15 N, and 2 ± 1 respectively). Simultaneously, the modification of pectin caused the non-uniform pores distribution. In addition, the different treatments had no significant correlation with the expansion ratio of the apple cubes, whereas the hardness and crispness of DIC dried apple cubes were related to the A22.

Characterization of Water Binding Properties of Apple Pectin Modified by Instant Controlled Pressure Drop Drying (DIC) by LF-NMR and DSC Methods

Effects of instant controlled pressure drop drying (DIC) on the hygroscopic behavior of water-soluble pectin (WSP), chelator-soluble pectin (CSP), and sodium-carbonate-soluble pectin (NSP) were explored to reveal the modification effect of DIC treatment on apple pectin and the correlations between water binding capacity and the inherent characteristic of pectin. The results showed that DIC treatment significantly increased the water binding properties of CSP even though it was decreased slightly in WSP and NSP. Meanwhile, the methylesterification degree (DE) of CSP decreased significantly by 43.04% whereas it was increased slightly in WSP and NSP. Although the effect of DIC on GalA contents and the changes in the functional group structures were negligible, the changes in the crystalline state of three pectin fractions were significant. The results suggest that there are strong correlations between the water binding properties and the DE and the crystalline state of the three pectin fractions after DIC drying.

Effect of Non-Conventional Drying Methods on In Vitro Starch Digestibility Assessment of Cooked Potato Genotypes.

Potatoes (Solanum tuberosum L.) are a good dietary source of carbohydrates in the form of digestible starch (DS) and resistant starch (RS). As increased RS content consumption can be associated with decreased chronic disease risk, breeding efforts have focused on identifying potato varieties with higher RS content, which requires high-throughput analysis of starch profiles. For this purpose, freeze drying of potatoes has been used but this approach leads to inaccurate RS values. The present study objective was to assess the starch content (RS, DS and total starch (TS)) of three cooked potato genotypes that were dried using freeze drying and innovative drying techniques (microwave vacuum drying, instant controlled pressure drop drying and conductive hydro-drying) relative to freshly cooked potato samples. Depending on the genotype, all drying methods showed one or more starch measures that were significantly different from freshly cooked values. The combination of ultrasound and infrared assisted conductive hydro-drying was the only method identified to be associated with accurate assessment of DS and TS content relative to fresh samples. The drying treatments were all generally associated with highly variable RS content relative to fresh controls. We conclude that freshly cooked samples must be used for selecting varieties with a high proportion of RS starch as drying of cooked potatoes leads to unreliable RS measurements.

Evaluation of sensory, textural, and nutritional attributes of shiitake mushrooms (Lentinula edodes) as prepared by five types of drying methods

AbstractThe effect of freeze drying (FD), far‐infrared radiation drying (FIRD), heat pump drying (HPD), hot air drying (HAD), and hot air combined instant controlled pressure drop drying (DIC) were compared on the drying efficiency and quality attributes of dried shiitake mushrooms. The results showed that in comparison with the HPD, HAD, and DIC, the FIRD shiitake mushroom exhibited better appearance with less shrinkage and lower ΔE (6.10), lower hardness (34.82 N), and higher rehydration ratio (7.55), which were more resemble to those of the FD sample. Besides, a significantly higher (p < 0.05) retention of protein was found in the FD and FIRD sample (2.47 mg/g and 2.30 mg/g), as well as higher retention of polysaccharide (1.79 mg/g and 1.39 mg/g). In addition, FIRD shiitake mushroom were superior to FD product in terms of saving drying time as 66.25% and exhibiting maximum numbers of flavor components, among which specific sulfides showed the highest percentage (24.59%). Therefore, the FIRD dried shiitake mushroom obtained a better overall quality among the products dried by the five drying methods.Practical applicationsShiitake mushrooms are wildly planted edible fungi, which are consumed mostly in dried form around the word. Recently, the demand of efficient application have promoted an increasingly use of novel drying technologies in mushroom processing. This study presents comprehensive evaluations on some vital quality attributes of shiitake mushrooms using five drying methods that already commercialized in China. FIRD was more suitable to produce dried shiitake mushrooms with desirable appearance and texture, as well as relatively rich flavor and nutrients.

Understanding the caking behavior of amorphous jujube powder by powder rheometer

Chinese jujube, rich in nutritional and nutraceutical values, is mostly preserved by drying in powder form. However, jujube powder is at amorphous state and prone to caking which has a negative impact on product manufacturability and quality. Effects of five different drying methods on caking of jujube powders were quantified by using the powder rheometer. In general, non-homogeneous caking of jujube powder was observed. Drying methods showed significant effect on the caking of jujube powder, powder dried by freeze drying and instant controlled pressure drop drying showed highest and lowest crust strength (622 and 170 mJ/g) at 25ᵒC, 75% RH for 5 h, respectively. Strength of caking increased with rising of RH and load. Temperature and time show coupled effect on powder caking and higher temperature could significantly accelerate caking strength of powders. When the moisture content of jujube powder was over 0.066 g/g at 25ᵒC, glass transition would happen. Structure of jujube powder would change from “amorphous glassy” to “amorphous rubbery”. Caking of particles was mainly due to sinter bridge formation and fructose was one of the main contributor to caking of jujube powder.

Novel Combined Freeze-Drying and Instant Controlled Pressure Drop Drying for Restructured Carrot-Potato Chips: Optimized by Response Surface Method

Combined freeze-drying and instant controlled pressure drop process (FD-DIC) for restructured carrot-potato chips was developed and its processing conditions were optimized using response surface methodology (RSM) with the purpose of improving the quality of products and reducing energy consumption. Three critical variables including the amount of carrot, the moisture content of the partially dried product before DIC treatment, and equilibrium temperature of DIC for the restructured chips were considered. Response parameters such as the final moisture content, color value (L, a, and b), and texture properties of restructured carrot-potato chips were investigated. The results showed that the graphical optimal ranges of FD-DIC drying process were as follows: the amount of carrot was 46–54% w/w, the moisture content of the partially dried product before DIC treatment was 0.20–0.35 g/g, and the equilibrium temperature of DIC was 85–95°C. Furthermore, the numerical optimization suggested that conditions were 47.43% w/w, 0.29 g/g, and 90.57°C, respectively. It could be concluded that the combined drying method of FD-DIC provided the restructured carrot-potato chips with higher quality, as compared to the freeze-dried chips. Considering the relatively high production cost of FD, this novel FD-DIC could be an alternative method for obtaining desirable restructured fruit and vegetable chips.

Structural and health functionality of dried goji berries as affected by coupled dewaxing pre-treatment and hybrid drying methods

ABSTRACTCoupled effects of sodium carbonate (SC) pre-treatment and hybrid drying methods (freeze-drying (FD)-instant controlled pressure drop drying (DIC), hot air drying (HAD)-DIC) on the microstructure, physicochemical, nutritional, and antioxidant properties of goji berries were investigated. Dewaxing pre-treatment by SC could decrease drying time and improve quality. A substantial increase in pore size of goji was found after SC pre-treatment coupled with hybrid drying. Although the best colour was found in FD products, goji dried by hybrid methods (especially FD-DIC) showed better overall quality than that dried by HAD or FD alone. FD-DIC products exhibited the lowest moisture content (127 g/kg), the best crispness (21), the highest glass transition temperature (27.82ºC), higher contents of total Lycium barbarum polysaccharide (139.8 g/kg), total carotenoids (2.43 g/kg) as well as ABTS+ radical scavenging activity (57.55 μmol TE/g). FD-DIC could be an alternative drying method for processing valuable agro-products.

Modification of Cell Wall Polysaccharides during Drying Process Affects Texture Properties of Apple Chips

The influences of hot air drying (AD), medium- and short-wave infrared drying (IR), instant controlled pressure drop drying (DIC), and vacuum freeze drying (FD) on cell wall polysaccharide modification were studied, and the relationship between the modifications and texture properties was analyzed. The results showed that the DIC treated apple chips exhibited the highest crispness (92) and excellent honeycomb-like structure among all the dried samples, whereas the FD dried apple chips had low crispness (10), the minimum hardness (17.4 N), and the highest volume ratio (0.76) and rehydration ratio (7.55). Remarkable decreases in the contents of total galacturonic acid and the amounts of water extractable pectin (WEP) were found in all the dried apple chips as compared with the fresh materials. The highest retention of WEP fraction (102.7 mg/g AIR) was observed in the FD dried apple chips, which may lead to a low structural rigidity and may be partially responsible for the lower hardness of the FD apple chips. In addition, the crispness of the apple chips obtained by DIC treatment, as well as AD and IR at 90°C, was higher than that of the samples obtained from the other drying processes, which might be due to the severe degradation of pectic polysaccharides, considering the results of the amounts of pectic fractions, the molar mass distribution, and concentrations of the WEP fractions. Overall, the data suggested that the modifications of pectic polysaccharides of apple chips, including the amount of the pectic fractions and their structural characteristics and the extent of degradation, significantly affect the texture of apple chips.

Research on the nonenzymatic browning reactions in model systems based on apple slices dried by instant controlled pressure drop drying

ABSTRACTIn this study, the influences of reducing sugar, amino acids, ascorbic acids, and phenolic compounds on the nonenzymatic browning reactions in model systems based on apple slices were studied. The browning components in apple slices were removed using water and ethanol sequently, and then infiltrated with different solutions. The browning ratio (BR) of apple slice model measured by a computer vision-based image analysis system was used to evaluate the nonenzymatic browning reactions. Compared to the solution containing reducing sugar and amino acids alone, the results showed that the reducing sugar and amino acid solution with the addition of (+)-catechin, L-epicatechin, and phlorizin resulted in a remarkable increment of BR in the apple slices. L-lysine, L-arginine, and L-cysteine showed higher positive effects on the formation of BR in models based on apple slices. This study was contributed to better understand the chemical reaction in real dehydrated apple slices.