Optimization of Short- and Medium-Wave Infrared Drying and Quality Evaluation of Jujube Powder

In this study, response surface methodology was used to optimize parameters of short- and medium-wave infrared drying processing for producing jujube powder. Optimization factors were power input (675–1,575 W), drying temperature (70–90 °C) and drying time (2.5–3.5 h), and responses were moisture content, L value, b value and vitamin C content of the jujube powder. Box–Benhnken center design was applied to the optimized the processing conditions. The optimal conditions for the production of jujube powder by the short- and medium-wave infrared drying method were power input of 1,125 W, drying temperature at 85.4 °C and drying time for 3.5 h. Under the optimal conditions, the values of moisture content, L, b and vitamin C content of jujube powder were 4.59 %, 64.46, 19.87 and 441.56 mg/100 g, respectively. Quality evaluation of the jujube powder was also investigated. The results were: hygroscopicity of 28.83 %, rehydration of 236.44 %, solubility of 53.59 %, bulk density of 0.70 g/ml, particle size of 154.2 μm, soluble solids content of 82.29 %, total sugar content of 46.87 %, reducing sugar content of 32.09 %, total acid content of 2.03 %, total flavonoids content of 1.45 % and cyclic adenosine monophosphate content of 75.32 mg/kg. The microstructure of jujube powder was irregular and 38 kinds of aroma components were generated.     

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.     

Effect of Process Parameters on Work Index, Milling Efficiency and Some Technological Properties of Yam Flour Using Attrition Mill

The effect of process parameters on work index, efficiency of milling, bulk density, swelling capacity and water absorption capacity of yam flour using attrition mill was studied. Independent variables were: moisture content (8, 12, 16, 20 and 24 % w.b.), speed (288, 346, 432, 576 and 864 rpm) and inlet opening (1,300, 2,600, 3,900, 5,200 and 6,500 mm²). The responses were work index, milling efficiency, bulk density, water absorption and swelling capacities of the flour. Work indexes for milling yam flour, meal and grit were found to be 0.25?±?0.13, 0.49?±?0.14 and 1.8?±?0.56, respectively. Flour fraction, bulk density, water absorption capacity and swelling capacity ranged from 42.2 to 56.6 %, 0.54 to 0.66 g/m³, 200 to 400 % and 13 to 23 ml, respectively. The treatments were found to influence the responses significantly (p?<?0.05). Optimum process condition was achieved at 12 % moisture content of feed, 506 rpm shaft speed and 5,200 mm² feed opening giving 19.1 % grit, 23.6 % meal and 54.2 % flour. The desirability of the optimisation process was 0.78. Validation of predicted optimal moisture content, worm shaft speed and feed inlet opening gave errors of 19, 14.4 and 6.1 % for grit, meal and flour, respectively.     

Glass Transition and State Diagram for Jujube Powders With and Without Maltodextrin Addition

Both water activity and glass transition concepts were used for stability evaluation of jujube powder in this study. The water sorption behaviour at 25, 35 and 45 °C and the relationship between water content (X _w), glass transition temperature (T _g) and water activity (a _w) were investigated for jujube powder with and without the maltodextrin addition. Moisture sorption isotherms of different jujube powders were of type III and BET model was the best for fitting the experimental data. The equilibrium moisture content of jujube powder containing 20% maltodextrin at a given a _w was lower than that of pure jujube powder. However, temperature had no significant effect on the moisture sorption of jujube powders. Values of T _g of different jujube powders were obtained using differential scanning calorimetry and the glass transition line was fitted to the Gordon-Taylor model. A depression in T _g with increasing water content was observed. State diagrams of different jujube powders were established based on the moisture sorption isotherm and the glass transition curve. Results showed that jujube powders with and without maltodextrin addition were stable at 25 °C when the water content was lower than 0.0673 and 0.0566 g/g solid, respectively.     

Effect of gum arabic concentration and inlet temperature during spray drying on physical and antioxidant properties of honey powder

The research studied the effect of gum arabic concentration at 35, 40 and 45 % with inlet temperatures of 160, 170 and 180 °C on the physico-chemical, functional and thermal properties of honey powder enriched with aonla (Emblica officinalis. Gaertn) and basil (Ocimum sanctum) extract, wherein other parameters like concentration of aonla extract (8 %), basil extract (6 %) and feed rate (0.11 mL/s) were kept as constant. Powder recovery and glass transition temperature (T_g) showed significant increase with the increase in inlet temperatures. On the other hand hygroscopicity, tapped density, total phenolic content, antioxidant activity and vitamin C content showed inverse response to the increase in inlet temperatures. However powder recovery, T_g, total phenolic content, antioxidant activity and vitamin C content increased with the increase in concentration of gum arabic. On the basis of obtained results it can be concluded that honey powder with the concentration of 45 % gum arabic at 170 °C inlet temperature was found to be less hygroscopic with better powder recovery and overwhelming antioxidant properties.     

Grape Marc Powder: Physicochemical and Microbiological Stability During Storage and Moisture Sorption Isotherm

In the present work, the stability of grape marc powder was evaluated during its storage at room conditions for 6 months. Grape juice marc from Vitis labrusca cv. “Isabel” was dried to 8.8?±?0.9 % moisture content (wet basis) in forced convection drying equipment at 70 °C, crushed and stored aseptically in dark polyethylene bags and kept at 25?±?2 °C for up to 6 months. Grape marc powder was microbiologically safe, free of Salmonella sp., Bacillus cereus, and fecal coliforms. Total phenolic compounds with 1,1-diphenyl-2-pic-ryl-hydrazyl (DPPH) scavenging capacity and ferric reducing antioxidant power (FRAP) were stable, although monomeric anthocyanins and compounds with the capability of scavenging 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals showed to be susceptible to degradation through the storage period. Moisture sorption isotherm at 25 °C for the powder material was determined by static gravimetric methodology. The sorption isotherm of the grape marc powder showed a sigmoidal shape (type II), typical of food materials. The experimental data was satisfactorily fitted by the GAB (Guggenheim–Anderson–de Boer) model, giving a monolayer moisture content (X _m) of 6.75 % (dry basis). Results indicate that grape marc powder can be considered as a potential functional ingredient with an acceptable stability.     

Drying of Garlic Slices Using Convective Pre-drying and Vacuum-Microwave Finishing Drying: Kinetics, Energy Consumption, and Quality Studies

Garlic slices were dehydrated by convective drying (CD) and by a combined method consisting of convective pre-drying followed by vacuum-microwave finishing drying (CPD-VMFD). Drying of garlic using VMFD led to samples with high values of lightness and slightly lower values of the coordinates a* and b*. The treatment CPD-VMFD significantly decreased the drying time from 630 min for CD to 49 min and contributed to an important energy saving compared with CD (54.4–86.3 %). The total drying time was shorter when vacuum microwaves were introduced earlier and microwave power was higher. The highest temperature (114 °C) was found for samples pre-dried to a moisture content of 60 % and then dried at 360 W while showing the lowest energy consumption (98?±?1 kJ?g^?1). In general, the total antioxidant capacity increased after drying of garlic slices; however, the content of total phenolic compounds showed the opposite trend, and thus other compounds, such as allicin, should be involved in the antioxidant capacity of dried garlic. Garlic slices were CP dried until 30 % of moisture content followed by VMFD at 240 or 360 W showed the best results in terms of energy consumption and antioxidant capacity.     

Effects of Enzymatic Liquefaction, Maltodextrin Concentration, and Spray-Dryer Air Inlet Temperature on Pumpkin Powder Characteristics

This study was conducted to investigate the effects of three variables namely cellulase (Celluclast, Novozymes, Denmark) concentration (0–1%, v/w (x ₁)), maltodextrin (MD) concentration (15–30%, w/w (x ₂)), and spray-dryer air inlet temperature (150–190 °C (x ₃)) on pumpkin powder characteristics using enzymatically macerated pumpkin with Pectinex® Ultra SP-L (2.5%, v/w). The powder characteristics considered as response variables in response surface methodology were process yield, moisture content, stickiness, water activity, and hygroscopicity. Results indicated that the response surface models were significantly (p?≤?0.05) fitted for all response variables in the studied independent variables range. The concentration of Celluclast and MD should be considered as critical factors which may increase process yield of pumpkin powder. The effect of Celluclast concentration on pumpkin powder characteristics especially for process yield and stickiness was noticeable. The main effect of MD and quadratic term of Celluclast had the most significant effect on stickiness. Negative interaction value of MD with Celluclast indicated that stickiness decreased when mixture of MD and Celluclast was used and also Celluclast reduced the impact of air inlet temperature on stickiness. The overall optimum region resulted in a desirable powder characteristics was predicted to be obtained by combined level of air inlet temperature 180 °C, Celluclast 0.7% (v/w), and MD 23% (w/w). The theoretical and experimental validation ensuring the adequacy of the response surface models described the changes in physical properties of powder as a function of Celluclast, MD, and air inlet temperature.     

冬枣粉吸湿的色泽、热力学特性及糖物质基础分析

为充分了解枣粉吸湿过程中的水分吸附特性,本研究采用静态称量法,分别测量枣粉在温度20、30、40 ℃,水分活度0.112～0.946下的吸湿情况,探究超微粉碎前后枣粉吸湿色泽的变化、吸附等温线、热力学性质及糖物质基础。结果表明,枣粉吸湿后褐变现象严重,其吸附等温线是III型,Peleg模型最适合描述枣粉的吸附等温线（平均相对预测误差E＜5%）。净等量吸附热和微分熵随着枣粉平衡水分含量（干基,下同）的增加呈指数降低,且超微粉低于普通粉。普通粉和超微粉的绝对安全水分含量分别为0.237 5、0.223 5 g/g。普通粉和超微粉的水分吸附过程均满足熵-焓补偿理论,其吉布斯自由能分别是1 152.80、1 184.22 J/mol,该过程是一个焓驱动的非自发反应。单糖吸湿对照实验结果表明枣粉中吸湿的主要糖种类为果糖。本研究旨在为枣粉的加工工艺优化及贮藏条件的选择提供理论依据。     

Evaluation of spray drying conditions on properties of microencapsulated oregano essential oil

Response surface methodology (RSM) was employed to investigate variations in powder characteristics with respect to spray drying operating parameters including both feed rates (L min^?1) and inlet temperatures (°C). Inlet temperatures around 180 °C provided the lowest values for moisture. Powder recovery was significantly affected (P < 0.10) by inlet air temperature and feed rate, where a raise in inlet temperature and feed rate resulted in higher powder recovery. No significant difference (P > 0.05) was observed for water activity, solubility and hygroscopicity between treatments. Regarding oil retention, the results showed a significant (P < 0.05) interaction between the two studied factors. A tendency for higher values of oil retention was observed when using combinations of high inlet temperatures/low feed rates and low inlet temperatures/high feed rates. Particle size distribution averaged 2.0, 8.1 and 18.3 μm for D₁₀, D₅₀ and D₉₀, respectively. The morphology of particles showed no cracks in most capsules. The results indicate that high temperature (185 °C) and moderated feed rate (0.63 L min^?1) are the best spray drying conditions.     

谷朊粉对冻干枣粉抑制吸湿作用研究

目的 研究谷朊粉对冻干枣粉吸湿特性的影响。方法 将谷朊粉与枣浆按不同比例均匀混合,真空冷冻干燥后粉粹,过60目筛制备不同配比的冻干枣粉。结果 谷朊粉显著降低了冻干枣粉的平衡含水率(equilibrium moisture content,EMC)。吸湿等温结果表明,红枣与谷朊粉质量比10:0、7:3、1:1、3:7样品的吸湿等温类型属“J”型增长,而0:10样品的属“S”型增长,表明谷朊粉的添加并未改变冻干枣粉吸湿等温类型;接触角随着谷朊粉的添加量的增大而增大,其值从31.22°增大到76.7°,说明谷朊粉可以减弱冻干枣粉的表面润湿性。从宏观和扫描电镜图中可知,冻干枣粉结块现象随着谷朊粉的添加量的增大而逐渐减轻。低场核磁结果显示,谷朊粉降低自由水的含量,减少水分向高自由度方向的迁移程度。结论 一定量的谷朊粉能够有效抑制冻干枣粉的吸湿,从而缓解结块的发生,保持流动性和分散性,进而提高冻干枣粉的品质。     

Maximization of Fructooligosaccharides and β-Fructofuranosidase Production by Aspergillus japonicus under Solid-State Fermentation Conditions

The conditions of temperature, moisture content, and inoculum rate able to maximize the production of fructooligosaccharides (FOS) and β-fructofuranosidase (FFase) enzyme by solid-state fermentation were established. Fermentation assays were performed using the support material (coffee silverskin) moistened to 60, 70, or 80 % with a 240-g/l sucrose solution and inoculated with a spore suspension of Aspergillus japonicus to obtain 2?×?10⁵, 2?×?10⁶, or 2?×?10⁷ spores/gram dry material. The fermentation runs were maintained under static conditions at 26, 30, or 34 °C during 20 h. The moisture content did not influence the FOS and FFase production; however, temperature between 26 and 30 °C and inoculum rate of approximately 2?×?10⁷ spores/gram dry material maximized the results (FOS?=?208.8 g/l with productivity of 10.44 g/l h; FFase?=?64.12 units U/ml with productivity of 4.0 U/ml h). These results are considerably higher than those obtained under no optimized fermentation conditions and represent an important contribution for the establishment of a new industrial process for FOS and FFase production.     

Production optimization,purification, and characterization of a novel acid protease from a fusant by Aspergillus oryzae and Aspergillus niger

The production of a novel acid protease was enhanced by 44 % through statistical optimization. The cultural parameters, such as inoculum size, temperature, moisture content, and incubation time, were 8.59 × 10⁵ g^?1 dry koji, 31 °C, 57 %, and 86 h, respectively. This novel acid protease was purified by 17 folds with a recovery yield of 33.56 % and a specific activity of 4,105.49 U mg^?1. Far-UV circular dichroic spectra revealed that this purified protease contained 7.1 % α-helix, 64.1 % β-sheet, and 32 % aperiodic coil. This novel acid protease was active over the temperature range of 35–55 °C with optimum temperature of 40 °C and was stable in the pH range of 2.5–6.5 with optimum pH of 3.5. Mn²⁺ enhanced its activity while Co²⁺ showed inhibitory effect. With casein as substrate, the kinetic parameters of K _m, V _max, energy of activation (E _a), and attenuation index of inactivation velocity by heat inducing (λ) were 0.96 mg mL^?1, 135.14 μmol min^?1 mg^?1, 64.11 kJ mol^?1, and 0.59, respectively.     

Spray Drying of Goat Milk Protein Hydrolysates with Angiotensin Converting Enzyme Inhibitory Activity

A goat milk hydrolysate was stabilized by spray drying using different inlet air temperatures (170–230 °C) and feed flow rates (4–12 mL/min) following a central composite experimental design. In order to evaluate the effect of operational conditions on process yield, powder properties (density, moisture, hygroscopicity, and solubility) as well as angiotensin converting enzyme (ACE) inhibitory activity, experimental data were analyzed by response surface methodology. Input variables showed a significant influence on yield, density, and moisture, while hygroscopicity, solubility, and ACE inhibitory activity were not affected. The dried hydrolysate presented an average IC₅₀ value of 273.13 μg/mL, which involved a loss of 25 % in ACE inhibitory activity with respect to the feed. The variations detected in the low molecular weight fractions of the dried hydrolysates could be responsible for the variations in ACE inhibitory activity.     

Influence of Microwave Treatment of Rapeseed on Minor Components Content and Oxidative Stability of Oil

Rapeseeds were adjusted to moisture contents of 9, 11, 13, and 15 % and treated with microwaves under 800 W for 0, 1, 2, 3, 4, 5, 6, and 7 min at a frequency of 2,450 MHz and oil was extracted with a press to investigate possibility of enhancing oil extraction yield by press, minor component content, and oxidative stability of the pressed oil. The results indicated that microwave pretreatment of rapeseed could increase the oil extraction yield, and both microwave time and initial moisture content of rapeseed had significant effects on the oil extraction yield (p?<?0.001). Total tocopherol content in the oil extracted by press first increased and then decreased depending on the period of microwave radiation (p?<?0.001), and the initial moisture content had no significant effect on the tocopherol content (p?>?0.05). Phytosterol and polyphenol contents increased with increasing microwave time and with decreasing initial moisture content of rapeseeds (p?<?0.001). An F test revealed there were significant interactions between the effects of microwave time and initial moisture content on both polyphenol content and oil extraction yield. The oxidative stability of oil were improved with increasing microwave time and decreasing initial moisture content (p?<?0.001), and there were significant positive correlations with total polyphenol and phytosterol contents. Therefore, it is advisable to treat rapeseeds with low initial moisture content by microwaves prior to oil extraction by press because it results in a relatively good oil extraction yield by cold press, with a high amount of phenolic, tocopherol, and phytosterol. Microwave pretreatment had a positive effect on oxidative oil stability in comparison to the untreated oil.     

Parameter optimization for spray-drying microencapsulation of jaboticaba (Myrciaria jaboticaba) peel extracts using simultaneous analysis of responses

The present study aimed to conduct a simultaneous optimization of different carrier agents and temperatures for the production of jaboticaba extracts by spray-drying microencapsulation. The 30% maltodextrin (control), 25% arabic gum + 5% maltodextrin and 25% Capsul™ + 5% maltodextrin carriers were used at air-drying inlet temperatures of 140, 160 and 180 °C. The following responses were evaluated: anthocyanin retention (AR), moisture content (MC), total solids (TS), hygroscopicity (H), overall color difference and antioxidant activity. Scanning electron microscopy (SEM) analysis was also performed. The AR, MC, H and overall color difference parameters were selected for simultaneous optimization by the desirability approach. The results showed that the highest desirability (0.7–0.8) was achieved when 30% maltodextrin was used at 180 °C. According to the SEM analysis, the use of maltodextrin and gum arabic allowed for the formation of more homogeneous particles, which is recommended in spray-drying microencapsulation.     

红枣粉喷雾干燥加工工艺优化

本研究通过向枣浆中加入大豆蛋白和果胶酶来优化红枣粉的喷雾干燥加工工艺,在单因素实验的基础上,利用响应面分析法优化料液浓度、进风温度、雾化器转速,以红枣粉集粉率和水分含量为响应值,最终得出喷雾干燥红枣粉的最优工艺参数:进料浓度18%,雾化器转速440 r/s,进风温度170 ℃,在此条件下经验证实验所得红枣粉出粉率为57.81%±0.75%,含水量4.76%±0.08%。此方法提高了红枣粉集粉率,改善了红枣粉的品质,为红枣制粉深入研究提供参考。     

Optimisation of process parameters to develop nutritionally rich spray‐dried honey powder with vitamin C content and antioxidant properties

The aim of present research was to optimise the conditions to develop nutritionally rich honey powder using honey, whey protein concentrate (WPC), aonla (Emblica officinalis. Gaertn) and basil (Ocimum sanctum) extract with the help of co‐current spray drier. Response surface methodology was applied to study the effects of inlet temperature (160–180 °C), whey protein concentrate (25–35%), feed flow rate (0.08–0.13 mL s^?1), aonla extract (6–8%) and basil extract (6–8%) on product responses, viz. bulk density, hygroscopicity, antioxidant activity (AOA), total phenolic content (TPC) and vitamin C. Statistical analysis revealed that independent variables significantly affected all the responses. The results demonstrated that increasing inlet temperature lowered the bulk density, hygroscopicity, AOA, TPC and vitamin C, whereas addition of aonla extract and basil extract increased the AOA (82.73%), TPC (63.27%) and total vitamin C content (94.89%) as these functional compounds were encapsulated by WPC. Similarly, with increase in feed flow rate and WPC, there was increase and decrease in the bulk density and hygroscopicity, respectively. The recommended optimum spray‐drying conditions were inlet air temperature (170 °C), feed rate (0.11 mL s^?1), whey protein concentrate (35%), aonla (8%) and basil extract (6%).     

A New Two-Step Chromatographic Procedure for Fractionation of Potato Proteins with Potato Fruit Juice and Spray-Dried Protein as Source Materials

In an effort to purify potato proteins of superior food grade quality, a new procedure involving anion exchange (ion exchange (IEX)) and hydrophobic interaction chromatography (HIC) was established. Liquid potato fruit juice (PFJ) or re-suspended spray-dried protein was separated by IEX yielding two fractions: a protease inhibitor (PI)-rich fraction and a patatin-rich fraction. Each of these fractions was re-chromatographed on HIC, resulting in two new sub-fractions which were characterised by electrophoresis and mass spectrometry. A high-quality powder should have high lightness, low polyphenol oxidase (PPO) activity and glycoalkaloid content below 150 μg/g. The PI fraction from spray-dried powder had high lightness (L* = 83) compared to patatin (L* = 50), whereas IEX purification from PFJ resulted in a PI fraction with decreased lightness (L* = 66) and a patatin fraction with increased lightness (L* = 68). HIC fractionation led to increased lightness for patatin fraction, but decreased lightness for the PFJ PI fractions. HIC purification significantly lowered PPO activity in the fractions due to its selective affinity. The lowest total glycoalkaloid content was generally found in HIC fractions from spray-dried powder (150 μg/g), while high levels (>1000 μg/g) were found in PI fractions from PFJ. In conclusion, it was possible to obtain a PI-rich protein isolate from powder with good-quality attributes after both IEX and HIC, while for patatin, the best quality was obtained after the HIC only, and there, the colour or PPO activity may still be a problem depending on source material.     

Effect of inlet temperature on the physicochemical properties of spray-dried seed-watermelon seed protein powder

Here, we studied the effects of inlet temperature on the physicochemical properties of the hydrolyzed protein (seed-watermelon seed hydrolyzed protein [SWSP]) powder in seed-watermelon seeds. The inlet temperature of the study was in the range of 150 to 180 °C, and the remaining experimental parameters remained constant, that is, the feed flow rate was 0.2 L/hr, the concentration of maltodextrin was 30%, and the outlet temperature was 80 °C. We studied the water activity and moisture content, bulk density, flowability (Carr index and Hausner ratio), angle of repose, solubility, color, hygroscopicity, powder morphology, particle size, crystallinity, and odor of the sample. Inlet temperature of 170 to 180 °C reduced the moisture content and increased the particle size. It was found that the value of measured water activity was less than 0.5, which helped in maintaining stability of the sample. Powders produced at the temperatures showed smoother particle surfaces, whereas higher inlet temperature showed spherical particles with some shrinkage as analyzed by scanning electron microscope. The inlet temperature affected the color of the sample, thus at high temperature, the sample had a brighter color. The sample was approximately 18% crystalline. At a preparation temperature of 160 °C, the sample showed significant antioxidant activity (P < 0.05).