Experimental and parametric study on drying of green peas in spouted bed

Drying of Green Peas (Pisum sativum) was studied experimentally in a lab‐scale spouted bed. Experiments were carried out at different operating conditions, and the effect of inlet air temperature and its flow rate, bed height (initial mass of wet particles) and average diameter of particles were examined on performance of dryer and rate of drying. The obtained experimental results were fitted by an exponential form equation to model the drying kinetic behaviour of green peas in a spouted bed. The fitting parameters are presented in the form of mathematical correlations as a function of operating parameters. As expected, it was found that by increasing inlet air temperature and air‐flow rate, the rate of drying increases, but by increasing the bed height and diameter of particles, the rate of drying decreases. The results can help the design engineers to choose the optimum drying conditions for industrial applications.     

喷动床在农产品干燥中的研究进展

农产品干燥是农产品加工业中一项非常重要的技术,为农产品原料的利用和新产品的开发提供了更多可能.能效和干燥产品的质量是农产品干燥的2个关键指标,喷动床干燥技术是这2个关键指标的有效提高途径之一.该文简述了喷动床技术在干燥农产品的应用中的研究进展,介绍了喷动床的结构、工作原理及其应用现状,分析了喷动床干燥农产品主要的优缺点...     

红外辐射在谷物干燥中的应用

阐述了红外辐射干燥的基本原理,分析了红外辐射在谷物干燥中的应用形式,提出了今后的研究方向.     

红外干燥粮食机理浅析

介绍了红外干燥谷物的机理,分析了红外干燥谷物的传质情况以及影响干燥效果的因素,从理论上说明了红外干燥较热风干燥更具优势.     

Drying kinetics and quality of okara dried in a jet spouted bed of sorbent particles

Okara or soy residue is a byproduct of soymilk and tofu production process. Okara has high protein content and can be used as an ingredient in many food products or can be used as animal feed. However, okara deteriorates rapidly; hence raw okara must be dried as early as possible under appropriate conditions. Drying could also help eliminating undesirable antinutritional factors in okara. The present study investigated the feasibility of drying okara using a combined convection-sorption drying, i.e., the use of a jet spouted bed of sorbent particles. The effects of various parameters such as drying air temperature and velocity, mass ratio of sorbent particles to okara, and initial bed height of okara on the drying kinetics were investigated. Also, various quality attributes of okara viz. color, oxidation level, rehydration ability, urease activity and protein solubility as well as the specific energy consumption during drying were investigated in both low- and high-temperature ranges.     

The effects of middle infrared radiation intensity on the quality of dried tomato products

The effects of air temperature (T) (unheated and 35 °C), infrared radiation intensity (IP) (894, 1004, 1190, 1314 and 1410 Wm^?2) and air velocity (Av) (1.0, 1.5 and 2.0 ms^?1) on drying characteristics of tomatoes, drying time (DT), specific energy consumption (SEC) and quality parameters were investigated. DT and SEC varied between 114 and 249 min, 10.04 and 18.22 MJ kg^?1 water, respectively, and were significantly affected by process variables. Shrinkage ratio (S) and rehydration ratio (R_r) were varied between 0.129 and 0.214, 2.11 and 2.86 for all the drying conditions, respectively. Total colour change (ΔE) varied from 5.30 to 13.19. Vitamin C content decreased, while lycopene content increased with infrared drying. For optimum points, desirability of functions of all targets had satisfactory, very good and excellent desirability values and ranged between 0.54 and 0.99.     

Physical properties of parboiled wheat and bulgur produced using spouted bed and microwave assisted spouted bed drying

The main objective of this study was to compare the spouted bed and microwave assisted spouted bed drying on affecting physical properties of parboiled wheat and bulgur. Drying was performed at different temperatures (50 °C, 70 °C, 90 °C) and microwave powers (288 W, 624 W). Bulk and apparent density, bulk and apparent porosity, sphericity, color, microstructure and pore size distribution of parboiled wheat were investigated after drying. Yield and water absorption capacity were determined in bulgur samples. The effect of air temperature on physical properties of product except color was not significant in spouted bed drying. More porous structure was observed in wheat samples dried in microwave assisted spouted bed compared to air dried ones. Sphericity and bulk density were higher when high temperature was combined with high microwave power. In microwave assisted spouted bed drying, similar yield value but lower water absorption capacity of bulgur were observed as compared to spouted bed drying.     

Relationship of ergosterol content and fungal contamination and assessment of technological quality of malting barley preserved in a metal silo using the near-ambient method

Environmental microbiologists frequently use ergosterol, a fungal-specific membrane lipid, as an indicator of fungal infection in grain and other plant materials. Microbiological loading and technological quality of barley was determined directly after harvest, after post-harvest drying, and during storage. The conventional plate count method was used to measure fungal contamination (CFU). Ergosterol concentration (ERG) was determined by extraction, saponification and quantification using high-performance liquid chromatography (HPLC) with UV detection. The laboratory malting method was used to determine technological quality of the malt. Results showed a significant correlation between ERG and CFU (the coefficient of correlation was 0.92). Analyses also indicated that the high germinative energy and technological quality of the malt produced from dried barley was retained.     

Influence of barley malting operating parameters on T-2 and HT-2 toxinogenesis of Fusarium langsethiae,a worrying contaminant of malting barley in Europe

The fungus Fusarium langsethiae, exclusively described in Europe at present, seems to have taken the place of other Fusarium species in barley fields over the last 5 years. It has proved to be a highly toxic type-A trichothecene producer (T-2 and HT-2 toxins). The aim of this work was to study the ecotoxinogenesis of this fungus the better to identify and manage the health risk it may pose during the beer manufacturing process. The influence of temperature and water activity on its growth rate and production of toxins are particularly assessed from a macroscopic point of view. Different cultures were grown on sterilized rehydrated barley with a water activity between 0.630 and 0.997 and a temperature ranging from 5 to 35°C. Biomass specific to F. langsethiae and T-2 and HT-2 toxins were quantified by real-time polymerase chain reaction and liquid chromatography-mass spectrometry, respectively. It appears that the optimal temperature and water activity for F. langsethiae toxinogenesis are 28°C and 0.997. This fungus was able to produce 2.22 g kg^?1 of these toxins in 16 days on barley in optimal production conditions. The malting process seems to be a critical step because, in its temperature range, specific production was six times higher than under optimal temperatures for fungus growth. In the short-term, this work will help redefine the process conditions for malting. In the medium-term, the results will contribute to the development of a molecular tool to diagnose the presence of this contaminant and the detection of the toxins in barley, from fields to the end product.     

草莓中短波红外干燥动力学拟合及品质变化分析

为了提高草莓干燥效率及产品品质,将中短波红外干燥技术应用于草莓干燥,研究不同干燥温度(60、70、80和90℃)和不同干燥功率(675、1 125、1 575和2 025 W)条件下的干燥特性和品质变化。草莓中短波红外干燥属于降速干燥过程,干燥速度快,且干燥温度较干燥功率影响显著;水分有效扩散系数范围为0.607×10-9~2.126×10-9m2/s,草莓中短波红外干燥的活化能Ea为39.54 k J/mol;通过模型拟合,表明最适合描述草莓中短波红外干燥的模型为Page模型。在干燥温度70℃,干燥功率1 125 W,干燥时间190 min下,草莓产品的色泽较好,复水比为3.59,硬度为3 128.01 N,VC的含量达到了259.93 mg/100 g,矢车菊素-3-葡萄糖苷的含量为0.23 mg/100 g,天竺葵素-3葡萄糖苷的含量为2.79 mg/100 g,草莓的综合品质较好。     

Drying and quality characteristics of fresh and sugar-infused blueberries dried with infrared radiation heating

We evaluated the finished product quality and infrared (IR) drying characteristics of fresh and sugar-infused blueberries dried with a catalytic infrared (CIR) dryer. IR drying tests were conducted at four product temperatures (60, 70, 80, and 90 °C) to evaluate the drying rate and the color and texture of the finished product. Fresh blueberries dried with convective hot air drying at 60 °C were used as control for comparison. The experimental data of moisture changes during IR drying were modeled with eight different models, including Page, modified Page, Thompson, Newton, Wang and Singh, and Henderson and Pabis, and two models developed in this study. The Thompson model showed the best fit to all experimental data. The CIR drying produced firmer-texture products with much reduced drying time compared with hot air drying. For fresh blueberries, CIR drying conserved drying time by 44% at 60 °C. The effective moisture diffusivity ranged from 2.24 × 10⁻¹⁰ to 16.4 × 10⁻¹⁰ m²/s and from 0.61 × 10⁻¹⁰ to 3.84 × 10⁻¹⁰ m²/s for fresh and sugar-infused blueberries, respectively.     

Effects of operating practices on performance of a fixed‐bed convection dryer and quality of dried longan

Bulk layer shifting during industrial drying of whole longan was evaluated. Analysis of drying conditions and product quality of samples from different areas of the dryer was conducted. The study found that both temperature and air velocity were non‐uniformly distributed during drying, which affected drying kinetics and product quality. High humidity and convective cooling of the drying air passing through the bulk caused condensation on fruits surfaces in the upper layer during the initial hours of drying. Those samples towards the sides of dryer, those initially in the upper layers, and especially those near the air inlet showed consistently lower quality. Four shifting schemes were tested, one of which was found to be exceptional in terms of end‐product uniformity. Issues concerning the improvement of industrial longan drying are addressed and an optimal shifting procedure is proposed.     

Residue levels of malathion and fenitrothion and their metabolites in postharvest treated barley during storage and malting

In order to investigate residue levels of malathion and fenitrothion and their metabolites (malaoxon, isomalathion and fenitrooxon) during storage and malting, pesticide-free barley was treated with these insecticides. Barley was placed in a sealed plastic container and treated with a dust of malathion (2%). Fenitrothion emulsion (41.6% wettable powder) was applied onto the walls of a small-scale storage vessel. Residues were determined in barley at about 1-month intervals during storage and in malt produced from the barley stored at various times. The analysis of the residues was carried out by GC equipped with a nitrogen-phosphorus detector (NPD). Although the approved doses of insecticides for stored grain were used, the residue levels exceeded the maximum residue limits (MRLs) at the beginning of storage. While the degradation of malathion and isomalathion in barley was observed to be about 65–72% during the storage period, the malaoxon was degraded extensively (85%). A significant percentage of fenitrothion residues (80%) were dissipated from grains for the short-term storage probably because of hot weather conditions. In malt, rates of degradation and volatilisation of the residues increased by the heat involved in malting. The carryover of the residues from barley into malt was also found to be dependent on the log P_ow (partition coefficient between n-octanol and water) values of the insecticides.     

Effect of hot air,vacuum and infrared drying methods on quality of rose hip (Rosa rubiginosa) leathers

For the development of fruit leathers, a formulation containing rose hip pulp, sucrose and citric acid was used as initial material for the drying process. Three dehydration techniques were tested: forced hot air, infrared and vacuum, all carried out at 60 and 70 °C. All methods led to flexible, translucent fruit leathers at both temperatures. Colour and water activity were not affected by the dehydration method nor by the temperatures tested. Nutritional parameters such as antioxidant capacity (TEAC) and content of phenolic substances were measured. The best retention was achieved with vacuum drying at 60 °C being of 57.5% and 25.1%, respectively. ESEM observations were conducted to assess the effect of drying methods and conditions on microstructure of leathers. Various extents of sucrose crystallisation were inferred from surface images. Cross‐sectional micrographs showed that the size of pores was affected by the drying technique but not by temperature in the range studied.     

Effects of infrared radiation heating on peeling performance and quality attributes of clingstone peaches

Salinity and wastewater disposal problems associated with the conventional wet-lye method for peeling clingstone peaches result in considerable negative environment impacts. The efficacy of using infrared (IR) heating as an alternative method for peach peel removal was investigated to eliminate the use of water and chemicals. Peaches sorted into three size categories were double-sided heated under IR with three emitter gaps for a range of heating times from 90 s to 180 s. Wet-lye peeling was used as a control. Results showed that 180 s IR heating for medium sized peaches under an emitter gap of 90 mm yielded 84 mm²/100 mm² peelability and 90 g/100 g peeling yield, produced peeled products with comparable firmness and color to wet-lye peeled peaches. Surface temperature increased rapidly (> 00 °C) during IR heating whereas the flesh temperature at 16 mm beneath skin remained relatively low (<45 °C). Thermal expansion of cell walls and collapse of cellular layers adjacent to skins were found in IR heated peaches and differed from the micro-structural changes observed in lye heated samples, indicating their mechanistic difference. Promoting uniform and rapid surface heating is essential to further develop IR heating as a non-chemical method for peach peeling.     

Performance of different drying methods and their effects on the chemical quality attributes of raw cocoa material

Studies were carried out to investigate the impact of different drying processes on the chemical quality traits of raw cocoa beans. The pH of less fermented cocoa is higher than the well‐fermented cocoa’s. The sun‐dried beans pH ranged from 4.5 to 5.5, while the pH of both oven‐ and mixed‐dried beans was between 3.8 and 5.2. The sun‐dried beans contained lower volatile acidity than oven‐dried beans. Artificially dried beans resulted in higher free acidity content when compared to both sun‐ and mixed‐dried beans. Ammonium nitrogen content in raw cocoa beans is not influenced by the drying methods. Free fatty acid content increases slowly but remains below the critical value of 1.75% whatever the drying processes. While oven‐dried beans show the FFA content above 0.70% both of sun‐ and mixed‐dried beans are associated with FFA content below 0.70%.     

Changes in β-glucan and other carbohydrate components of barley during malting

Changes in total (1→3), (1→4)-β-glucan content were followed during the micro-malting of nine varieties of barley with a wide range of malting qualities. These changes were related to estimates of endosperm modification based upon staining with Calcofluor. β-Glucan content declined from an average of 3.54% in the barley to 0.75% in the malt. Pentosan and total starch (including starch-derived oligosaccharides) levels showed comparatively little change during malting. β-Glucan composition of the barley was a poor indicator of malting performance. However, the β-glucan, starch and xylose contents of the malt all showed significant correlations with malt extract. Estimation of malt β-glucan content gave the best indication of malt quality. Direct determination of β-glucan may be of more value in assessing malt quality than indirect techniques based upon assessing modification of stained grains.     

Drying kinetics using superheated steam and quality attributes of dried pork slices for different thickness, seasoning and fibers distribution

Drying pork slice by superheated steam was proposed in this study. Sirloin muscle pork meat was sliced parallel and perpendicular to the fiber direction with thicknesses of 1 and 2 mm. The sliced samples were divided into two groups; unseasoned and seasoned pork, and were dried by superheated steam at a temperature of 140 °C. The experimental results showed that thicker pork slice needed more drying time, which led to more shrinkage, darker and redder dried product as compared to the thinner pork slice. Seasoning also extended the drying time of the seasoned pork slice and made the dried seasoned pork slice darker and yellower, but less in the values of hardness, toughness and shrinkage. Slicing directions did not have any significantly effect on drying time and color of dried pork slice. The parallel slice, however, lowered the values of hardness, toughness and shrinkage of dried pork.     

Evaluation of the use of attenuated total reflectance mid infrared spectroscopy to determine fatty acids in intact seeds of barley (Hordeum vulgare)

Attenuated total reflectance (ATR) mid-infrared (MIR) spectroscopy was evaluated to measure fatty acids (FA) and total lipids in intact seed barley (Hordeum vulgare) samples. Results from this study demonstrated the capability of ATR-MIR spectroscopy coupled with partial least squares (PLS) regression to measure FA non-destructively in intact barley seeds. The coefficients of determination in cross validation (R²) and the standard error of cross validation (SECV) were 0.76 and 0.004 g 100 g⁻¹ for stearic, 0.75 and 0.037 g 100 g⁻¹ for oleic, 0.45 and 0.02 g 100 g⁻¹ for palmitic acids, and 0.89 and 0.13 g 100 g⁻¹ for total lipids, respectively. The practical implications of this study showed that ATR-MIR spectroscopy confer valuable benefits for the grain industry and in particular in breeding programs as a non-destructive high throughput method.