Impact of trehalose,sucrose and/or maltodextrin addition on aroma retention in freeze dried strawberry puree

Trehalose was studied as a drying aid to establish its impact on aroma retention in freeze dried strawberry puree. The evaluation was done by sensory analysis and headspace‐solid phase microextraction‐gas chromatography with a mass detector (HS‐SPME‐GC‐MS); results were compared with those obtained using sucrose and maltodextrin (MD) as drying aids. The carbohydrate used significantly modified the type and concentration of volatiles retained during freeze drying. HS‐SPME‐GC‐MS outcomes showed that the use of trehalose (alone or with MD) resulted in the product with the chromatographic profile most similar to fresh strawberry puree, being different from sucrose and MD. Meanwhile, sensory analysis showed a similarity with the aromatic profiles when using trehalose or sucrose, remaining both different from MD. This study proved that the use of trehalose as a drying aid can be beneficial on volatile aroma retention and that different combinations of organic volatiles can lead to similar sensory profiles.     

Moisture sorption characteristics and glass transition temperature of apple puree powder

The aim of this study was to characterise the influence of different foam‐mat‐drying methods on the moisture sorption characteristics and glass transition temperatures of apple puree powder. Apple puree was foamed with the addition of 2.5% egg albumin and 0.5% methylcellulose. Convective air‐drying and microwave‐drying techniques were used. Also foamed puree with and without maltodextrin (6% or 15% w/w) was freeze‐dried. Moisture equilibrium data of powders were determined by using a static desiccator method in a water activity range of 0.0–0.903. Modulated differential scanning calorimetry (MDSC) was used to obtain the glass transition temperature. No effect of drying method on sorption properties and glass transition temperatures of apple puree powders was observed. The addition of maltodextrin to the apple puree caused an increase in T_g by 10–30 °C depending on the amount of incorporated additive. Addition of maltodextrin significantly reduced the hygroscopicity of apple puree powders.     

Nutritional and rheological characterization of spray dried sweetpotato powder

Spray drying feasibility of sweetpotato puree is enhanced using alpha-amylase treatment to reduce puree viscosity and maltodextrin (MD) addition to facilitate drying. To better determine potential applications of powders produced with various levels of amylase and MD, nutrient composition and rheological properties of the hydrated spray dried sweetpotato powders were examined and compared with sweetpotato puree. Proximate composition, beta-carotene, vitamin C, and mineral analyses were performed. Steady shear rheology of reconstituted powder solutions was also evaluated at different temperatures and shear rates. Spray drying significantly reduced the β-carotene and ascorbic acid contents. Additionally, the all-trans form of beta-carotene was further transformed to the cis-isomers during dehydration. The viscosity of the reconstituted solutions was much lower than that of the puree at the same solid concentration. Rheologically, the reconstituted sweetpotato slurries behaved similarly to pregelatinized starch solutions. Thus, spray dried sweetpotato powders have a potential to enhance food systems as a thickener despite the need for increased nutrient retention.     

Effect of freezing rate on quality parameters of freeze dried soursop fruit pulp

The effect of freezing rate on the final moisture and ascorbic acid content, water solubility, wettability and color of freeze dried soursop fruit pulp treated with maltodextrin was studied. Different size ice crystals derived from distinct freezing rates origins diversity of product specific surface area that influence both water desorption and water dissolution, but in opposite manners. After a constant drying time of 6 h the moisture content of the dried samples was in the range of 8.68–13.09% being higher for higher values of freezing rate. An inverse linear dependence between initial freezing rate and final water solubility (85.75–81.51%) of freeze dried samples was also found. Faster freezing rates also affected the wetting time (0.36–1.26 min) because they produced decreasing in pore size and simultaneously increasing in capillary tortuosity of the final micro-structure of the dried samples. Freeze-dried powders were much brighter in color compared to the maltodextrin treated pulp. Among the freeze dried samples, those prepared with higher freezing rates were lighter in color.     

Trehalose improves flavour retention in dehydrated apricot puree

The influence of the addition of two sugars (trehalose and sucrose) on the retention of volatiles responsible for the characteristic aroma in dehydrated apricot puree was studied. Aroma compounds of fresh and both freeze‐dried and foam‐mat‐dried apricot puree were analysed by manual headspace solid‐phase microextraction coupled with gas chromatography (GC‐FID and GC‐MS). The best retention of aroma compounds in dehydrated apricot puree was obtained when trehalose was added, regardless of the dehydration process used (freeze drying or foam‐mat drying), although, generally, a much higher retention of flavour volatiles was obtained in freeze‐dried purees. Principal Component Analysis and Cluster Analysis were applied to all the apricot purees studied to obtain a simplified view of the relationship among the aroma compounds in dehydrated apricot purees. This study gives further insights into the mechanisms that occur when trehalose is applied as an additive and will enable the development of new processes to maximize this effect and to produce superior dried products.     

The effect of trehalose, sucrose and maltodextrin addition on physicochemical and sensory aspects of freeze - dried strawberry puree

Use of trehalose as a novel drying aid to produce freeze-dried strawberry puree was studied and compared with conventional drying aids for fruit purees, namely sucrose and maltodextrin (MD). Glass transition temperature ( T _g), colour, sensory profile and consumer preference were determined. Purees dried with MD and/or trehalose presented higher T _g values as compared to sucrose. Sensory evaluation indicated that samples dried with trehalose retained fresh strawberry aroma and flavour, keeping a good sweetness/sourness balance, while puree dried with sucrose was mostly sweet. Addition of MD caused an increase in products visual viscosity and sourness, attributes which were negatively correlated to preference. Trehalose presented several advantages for increasing the quality of freeze dried fruit purees. It raised T _g, gave an adequate sweetness/sourness balance, and allowed a better perception of fresh strawberry flavour.     

Anthocyanin colourants from elderberry (Sambucus nigra L.). 2. Process considerations for production of a freeze dried product

Freeze drying of elderberry anthocyanin extract under the proper conditions produces an intensely coloured powder with retention of both anthocyanins and physical structure. The various conditions examined included extract concentration, stabilizer concentration, pH and freeze drying conditions. It was found that minimum antho-cyanin degradation and product structure alteration occur, when the undiluted extract is adjusted to pH = 3, has DE 20 maltodextrin structure stabilizer added to a 2.5% level and is freeze dried at a maximum platen temperature of 75â°C and maximum product temperature of 60â°C. Under these conditions, the recovery of anthocyanin is 94% and physical structure and solubility is preserved.     

Effect of Combining Mechanically Harvested Green and Ripe Puree and Sliced Fruit, Processing Methodology and Frozen Storage on Quality of Strawberries

Small green and ripe mechanically harvested strawberries were processed into puree and combined with 60 and 80% sliced ripe fruit to determine the effects of holding after harvest, percent green fruit in puree, processing procedure and storage on quality of frozen sliced strawberries. Green and ripe fruit puree added to the sliced strawberries resulted in higher viscosity and lower ascorbic acid, total anthocyanins and red color as compared to packs with 100% sliced ripe fruit. The mixtures of sliced ripe fruit and up to 40% puree were rated acceptable by a sensory panel. Heating the puree may be beneficial to color during long-term storage. Holding of fresh strawberries for 24 hr at 24°C after cleaning decreased the ascorbic acid, viscosity of syrup and color of the frozen pack. Storage of the frozen product decreased ascorbic acid and color.     

不同干燥方式对黑毛豆仁品质的影响

研究热风干燥、微波干燥、热风-气流膨化干燥、微波-气流膨化干燥、冷冻干燥5种不同的干燥方式对黑毛豆仁品质(VC和花色苷保留率、色泽、硬度、脆度、感官质量和微观结构)的影响。结果表明：冷冻干燥黑毛豆仁的VC和花色苷保留率最高、色泽良好,但硬度过低;微波干燥黑毛豆仁在VC和花色苷保留率方面仅次于冷冻干燥,产品的色泽和风味差;热风干燥黑毛豆仁的品质最差;热风-气流膨化干燥黑毛豆仁的品质次于微波-气流膨化的;微波-气流膨化干燥黑毛豆仁在VC和花色苷保留率、色泽方面与微波干燥产品无显著性差异,硬度和脆度得到了明显的改善,产品的感官质量较好,可作为最佳干燥方式应用于生产。     

Quality Retention in Strawberry and Carrot Purees Dried with Refractance WindowTM System

ABSTRACT: The quality retention characteristics of strawberry and carrot purees dried using the Refractance Window^TM (RW) drying method were evaluated against freeze drying, drum drying, and spray drying methods. Ascorbic acid retention of the strawberry purees (94.0%) after RW drying was comparable to 93.6% in freeze-drying. The carotene losses for RW drying were 8.7% (total carotene), 7.4% (α-carotene), and 9.9% (β-carotene), which were comparable to losses of 4.0% (total carotene), 2.4% (α-carotene), and 5.4% (β-carotene) for freeze-dried carrot purees. The color of the RW-dried carrot purees was comparable to fresh puree. For RW-dried strawberry purees, the color retention was comparable to freeze-dried products. RW drying altered the overall perception of aroma in strawberries.     

Preparation of High‐Grade Powders from Tomato Paste Using a Vacuum Foam Drying Method

We present a rapid and gentle drying method for the production of high‐grade tomato powders from double concentrated tomato paste, comparing results with powders obtained by foam mat air drying and freeze dried powders. The principle of this method consists of drying tomato paste in foamed state at low temperatures in vacuum. The formulations were dried at temperatures of 50, 60, and 70 °C and vacuum of 200 mbar. Foam stability was affected by low serum viscosity and the presence of solid particles in tomato paste. Consequently, serum viscosity was increased by maltodextrin addition, yielding optimum stability at tomato paste:maltodextrin ratio of 2.4:1 (w/w) in dry matter. Material foamability was improved by addition of 0.5% (w/w, fresh weight) egg white. Because of solid particles in tomato paste, foam air filling had to be limited to critical air volume fraction of Φ = 0.7. The paste was first pre‐foamed to Φ = 0.2 and subsequently expanded in vacuo. After drying to a moisture content of 5.6% to 7.5% wet base (w.b.), the materials obtained were in glassy state. Qualities of the resulting powders were compared with those produced by freeze and air drying. Total color changes were the least after vacuum drying, whereas air drying resulted in noticeable color changes. Vacuum foam drying at 50 °C led to insignificant carotenoid losses, being equivalent to the time‐consuming freeze drying method. In contrast, air drying caused lycopene and β‐carotene losses of 18% to 33% and 14% to 19% respectively. Thus, vacuum foam drying enables production of high‐grade tomato powders being qualitatively similar to powders obtained by freeze drying.     

Addition of cashew tree gum to maltodextrin-based carriers for spray drying of cashew apple juice

This study involved an attempt to totally or partially replace maltodextrin DE10 (MD10) by cashew tree gum (CTG) as a drying aid agent in spray drying of cashew apple juice. The objective was to evaluate the impact of drying aid/cashew apple juice dry weight ratio (D/C, ranging from 3 to 5) and degree of replacement of MD10 with CTG (CTG_R, ranging from 0% to 100%) on ascorbic acid retention (AAR), hygroscopicity, flowability and water solubility of spray dried cashew apple juice powder. AAR was increased from 72.90% to 95.46% by increasing D/C from 3 to 5. CTG was shown as a promising maltodextrin replacer, being more effective than the latter to decrease powder hygroscopicity. The most adequate drying conditions (D/C = 5, CTG_R≥50%) resulted in more than 90% of AAR, and produced a powder with good flowing properties and water solubility.     

Effect of Dehydration on Raspberries: Polyphenol and Anthocyanin Retention, Antioxidant Capacity, and Antiadipogenic Activity

ABSTRACT:  Fresh and dried raspberries prepared by freeze drying (FD), microwave-vacuum (MIVAC), hot-air drying (HAD), and a combination of hot-air drying and microwave-vacuum (HAD/MIVAC) drying methods were evaluated for polyphenol retention, total polyphenol and anthocyanin contents, total antioxidant capacity, and antiadipogenic activity (the inhibition of fat cell development). Ellagic acid and quercetin were present in the largest concentrations in fresh and dehydrated raspberries. Dehydration led to a loss of polyphenols and anthocyanins and antioxidant capacity. Polyphenols (aglycone form) were retained in the greatest amount: 20% (freeze dried) to 30% (HAD/MIVAC) (fresh = 100%). A total of 30% of polyphenols (glycoside form) were retained in raspberries dried by the HAD/MIVAC methods with 5% of retention observed for raspberries dried by FD, HAD, or MIVAC. FD and MIVAC resulted in higher retention of anthocyanins (aglycone form) than other drying methods. It was also observed that antioxidant activity was reduced by dehydration. Adipogenesis was inhibited by polyphenolic glycosides (30%) and aglycones (30% to 40%) in fresh and HAD/MIVAC raspberries. Extracts from dried raspberries by HAD/MIVAC methods were relatively more effective at inhibiting adipogenesis compared to HAD and FD dried raspberries.     

Survival of Bifidobacterium longum 1941 microencapsulated with proteins and sugars after freezing and freeze drying

Five types of proteins and three types of sugars were examined for their effectiveness in protecting B. longum after freeze drying, including their acid and bile tolerance, surface hydrophobicity, retention of β-glucosidase, lactate dehydrogenase and adenosine triphosphatase. Sodium caseinate 12%, whey protein concentrate 12%, sodium caseinate:whey protein concentrate 6%:6%, skim milk 12%, or soy protein isolate 12% was combined with glycerol (3% w/v), mannitol (3% w/v) or maltodextrin (3% w/v). Fifteen emulsion systems containing sugars were obtained. Concentrated B. longum 1941 was incorporated into each emulsion system at a ratio of 1:4 (bacteria:emulsion). All the mixtures were then freeze dried. Water activity (a_w) of freeze dried microcapsules was in the range of 0.30 to 0.35. WPC–CAS GLY provided high stability of bacteria (99.2%) during freezing, while high stability of cells after freeze drying and during exposure to acid and bile environment was achieved when CAS–MAN was applied (97.4%, 81.6% and 99.3%, respectively). High retention of β-glu of freeze-dried bacteria was achieved using SM–MAN as protectant (94.6%). ATPase and LDH were successfully retained by SM–GLY (94.9 and 83.6%, respectively) but there was no significant difference in protection effect using CAS–MAN (93.8 and 82.6%, respectively). Overall, milk proteins were superior to SPI and sugar alcohols provided more protection than MD.     

Optimization of bayberry juice spray drying process using response surface methodology

In this study, thirteen different runs according to the central composite design-response surface methodology were used to optimize the quality parameters of spray-dried bayberry juice powder. The independent variables were different levels of inlet air temperature (145.8–174.1 °C) and maltodextrin concentration (22.9–37.0%). The responses were process yield, moisture content, hygroscopicity, glass transition temperature (Tg), total color difference (ΔE), redness, retention of phenolics and anthocyanins, and antioxidant capacity. The optimum operation conditions for the highest Tg, redness, anthocyanins retention and antioxidant capacity with the lowest ΔE and hygroscopicity were obtained at inlet drying temperature of 150 °C and maltodextrin concentration of 31%. This study revealed that by applying these optimal conditions, bayberry juice powder with a 74.16% yield, 3.15% moisture content, 10.25% hygroscopicity, 41.15 °C Tg, 24.74 ΔE, 27.45 Hunter a redness, 89.55% anthocyanins retention, 77.71% phenolics retention, and 30.19 mmol Trolox equivalents/g antioxidant capacity was produced.     

Infrared-assisted freeze-drying (IRFD) of açai puree: Effects on the drying kinetics,microstructure and bioactive compounds

Comparison between near and far wavelength sections were evaluated in the infrared-assisted freeze-drying (IRFD) process of açai puree. Samples were dried using freeze drying (FD); near IRFD (NIRFD); far IRFD (FARFD); and infrared heating after 20% weight reduction, NIRFD_20%WR and FARFD_20%WR. IRFD significantly reduced the total drying time, with NIRFD and FARFD taking 49.42% and 33.40% less time than FD, respectively. The structure of powdered using IRFD was more open and with larger pores. FARFD_20%WR had collapsed cells that compromised the functional properties of the powder (wettability, dispersibility). As for bioactive compounds, phenolic content was not affected by IRFD, ranging from 963.44 to 1025.60 mg/100 g. Antioxidant capacity increased (59.91 to 88.06%) when far infrared was used due to a Maillard reaction that generated antioxidant compounds and darker product. Content of anthocyanins reduced in samples dried by far infrared. Overall, NIRFD was more efficient, as it reduced total drying time without compromising product quality.Industrial relevanceThe high-energy consumption of traditional freeze-drying limit the large-scale industrial production of freeze-dried açai puree. The infrared-assisted freeze-drying has been contributions on reducing drying energy consumption with time saving varying from 24.73 to 49.42% compared to the conventional freeze-drying treatment, maintaining the color, appearance and nutritional quality of the açai puree. Besides that, this study outstands that near wavelength lamps are more suitable for food drying by IRFD.     

A novel infrared freeze drying (IRFD) technology to lower the energy consumption and keep the quality of Cordyceps militaris

A novel laboratory scale apparatus using infrared lamps replacing the electric heating plate for the freeze drying of Cordyceps militaris was developed in this study. The drying time, energy consumption, nutritional properties, antioxidant activities and main volatile compounds of Cordyceps militaris dried by infrared freeze drying (IRFD) and traditional freeze drying (TFD) at different drying temperatures (40, 50, 60 and 70 °C) were compared. Results indicated that drying at 40, 50 and 60 °C resulted in higher retention of cordycepin, total phenolics, hydroxyl radical scavenging activity, reducing power, 3-octanone, 3-octanol and 1,3-octadiene when compared with those dried at 70 °C. IRFD could reduce 7.21–17.78% of the drying time and 11.88–18.37% of the energy consumption at a constant drying temperature in comparison of TFD. In terms of quality, IRFD and TFD had similar retention effects on cordycepin, adenosine, hydroxyl radical scavenging activity and reducing power. Consequently, the results suggest that IRFD should be a promising approach for achieving high-quality dried products.Industrial relevance.IRFD could reduce 7.21–17.78% of the drying time and 11.88–18.37% of the energy consumption at a constant drying temperature in comparison of TFD without compromising the quality of the dried product. This study can help food processing industries to produce high quality freeze dried Cordyceps militaris and many other foods with an energy efficient freeze drying process.     

Physicochemical properties and storage stability of spray‐dried soya bean sprout extract

Amylase is a very important enzyme due to its wide food applications. To preserve amylase activity in soya bean sprout extract (SSE), SSEs were spray‐dried with 10% maltodextrin and 0–3% alginic acids, and their physicochemical properties and storage stability were compared with freeze‐dried one. SSE exhibited maximum amylase activity at pH 7.0 and 60 °C, with the most active substrate specificity towards soluble starch. Spray‐dried SSEs exhibited higher water solubility index (WSI) and in vitro relative amylase activity but lower water vapour sorption (WVS) and smaller particle size than freeze‐dried SSE. For spray‐dried SSEs, particle size, WSI and in vitro relative amylase activity increased while WVS decreased with increasing % alginic acid. This study demonstrated that spray drying of SSE, especially with 10% maltodextrin and 2% alginic acid, was effective in keeping amylase active and stable during 7‐week storage at room temperature (25 °C).     

Spray-Drying of Amylase Hydrolyzed Sweetpotato Puree and Physicochemical Properties of Powder

ABSTRACT:  Spray-drying, which has been used for commercial production of functional ingredients from several fruits and vegetables, has not yet been studied for sweetpotato processing. Thus, the objective was to determine the effects of viscosity reduction of sweetpotato puree with alpha-amylase, maltodextrin (MD) addition, and inlet air temperature on the physicochemical characteristics of spray-dried sweetpotato powder. A face-centered cube design was used to evaluate the effects of amylase level (0, 3.75, and 7.5 mL/kg puree), MD concentration (0%, 10%, and 20%), and inlet air temperature (150 °C, 190 °C, and 220 °C) on powder characteristics. Model-fitting using response surface methodology was performed to examine the effects of independent variables on the moisture content, color, water absorption, solubility, particle size, bulk density, and glass transition temperature. The data were fit to a full second order polynomial equation. However, only the linear and quadratic terms proved to be significant for most dried powder attributes. MD significantly increased powder solubility, altered the hue value, and raised the glass transition temperature of the powder. Pretreatment with alpha-amylase resulted in a lower glass transition temperature and a decrease in particle size. Overall, results show that good quality sweetpotato powders can be produced using this drying method, with potential applications in food and nutraceutical products.     

Foam-mat drying technology: A review

This article reviews various aspects of foam-mat drying such as foam-mat drying processing technique, main additives used for foam-mat drying, foam-mat drying of liquid and solid foods, quality characteristics of foam-mat dried foods, and economic and technical benefits for employing foam-mat drying. Foam-mat drying process is an alternative method that allows the removal of water from liquid materials and pureed materials. In this drying process, a liquid material is converted into foam that is stable by being whipped after adding an edible foaming agent. The stable foam is then spread out in sheet or mat and dried by using hot air (40–90°C) at atmospheric pressure. Methyl cellulose (0.25–2%), egg white (3–20%), maltodextrin (0.5–05%), and gum Arabic (2–9%) are the commonly utilized additives for the foam-mat drying process at the given range, either combined together for their effectiveness or individual effect. The foam-mat drying process is suitable for heat sensitive, viscous, and sticky products that cannot be dried using other forms of drying methods such as spray drying because of the state of product. More interest has developed for foam-mat drying because of the simplicity, cost effectiveness, high speed drying, and improved product quality it provides.