Optimization of microwave-vacuum drying of pomegranate arils

Pomegranate arils (Punica granatum L.) were dried in a microwave-vacuum drier up to a final moisture content of around 5–6 % (d.b.). The effect of microwave power level (25–95 W), vacuum pressure (25–195 mm Hg) and sample mass (65–235 g) on drying efficiency and some quality attributes (color, texture, rehydration ratio and sensory score) of dried pomegranate arils were analyzed by means of response surface methodology. A rotatable central composite design was used to develop models for the responses. Analysis of variance showed that a second order polynomial model predicted well the experimented data. All three process parameters microwave power, vacuum pressure and sample mass strongly affected quality attributes of dried pomegranate arils and drying efficiency. A lower vacuum pressure during drying resulted in better quality products. Optimum drying conditions of microwave power level of 80 W, vacuum pressure of 60 mm Hg and sample mass of 193.7 g were established for microwave-vacuum drying of pomegranate arils. Separate validation experiment was conducted at the derived optimum conditions to verify the predictions and adequacy of the models.     

Drying Kinetics and Energy Consumption in the Dehydration of Pomegranate (Punica granatum L.) Arils and Rind

The objective of this study was to evaluate the drying kinetics and energy requirements during convective drying (CD) (50, 60 or 70 °C), vacuum-microwave drying (VMD) (240, 360 or 480 W) and a combined method of convective pre-drying and vacuum-microwave finishing drying (CPD-VMFD) while processing pomegranate arils and rind. Drying kinetics of CD and VMD was described using seven basic drying models; however, VMFD was modeled only by the Henderson and Pabis equation. Pomegranate rind required less drying time (26–460 min) than arils (51–1,395 min) due to its higher porosity and lower sugar content. The drying time and the energy consumption were reduced when the air temperature and microwave wattage were increased. VMD required less energy than CD within the entire range of moisture content assayed. CD energy consumption can be reduced by its combination with VMD (CPD-VMFD), and this reduction was more important when the VMFD was applied earlier. VMD and CPD-VMFD are a good option for food drying industry in order to reduce both the drying time and the energy consumption while processing pomegranate arils and rind. Therefore, industries can optimise the drying process and consequently save their financial needs.     

Some physical properties of paddy and rice and their interrelations

Grain dimensions, density, bulk density, porosity and angle of repose of paddy and rice were studied with respect to (a) varietal difference, (b) effect of moisture content, and (c) effect of degree of milling.

• (a) Grain breadth and thickness were mutually correlated; all dimensions of milled rice were closely related to those of the corresponding paddy. Density was nearly constant at 1.452 g/ml in all rice varieties; in paddy, the value was around 1.182 g/ml for round varieties and around 1.224 g/ml for others. Bulk density varied appreciably in both rice (0.777–0.847) and paddy (0.563–0.642 g/ml), and so did porosity (41–46% in rice, 46–54% in paddy). These were related to the grain shape (l/b ratio); the more round the grain, the greater was the bulk density and the lower the porosity and vice versa. Angle of repose was relatively constant in different varieties of rice (average 37.5°) and paddy (average 36.5°).
• (b) With increasing moisture content, in rice, density decreased linearly; but the bulk density decreased twice as fast and the porosity increased owing to a concurrent progressive increase in the frictional property which decreased the degree of grain packing. In paddy, with increasing moisture content, density and bulk density increased, showing the presence of void space between the husk and the kernel; the angle of repose also increased moderately, but the porosity remained nearly constant.
• (c) Density of rice increased slightly with milling; but bulk density, porosity and angle of repose were markedly affected by the degree of milling. In general, with progressive milling, bulk density decreased at first and then increased, while porosity and angle of repose changed in reverse fashion—the changes being more pronounced in parboiled rice than in raw rice. Thus brown rice packed well and flowed freely; rice of intermediate polish, particularly parboiled rice, had poor packing and flow properties; and fully milled rice again packed and flowed well. The primary change in these was in frictional property, which affected the porosity and hence the bulk density. The frictional property in turn was related primarily to the surface fat content of the rice. The surface fat increased sharply on initial milling, more in parboiled rice, and then gradually disappeared on full milling.

     

Moisture-Dependent Physical Properties of Kola Nut (Cola nitida) Seed

This study was carried out to determine the effect of moisture content on some physical properties of kola nut seed. Four moisture levels ranging from 47.48 to 61.4 % wet basis (w.b.) was considered. Results showed that there was linear increase in the mean length, width, thickness, geometric mean diameter, surface area, volume, sphericity, aspect ratio, 1,000 nut mass, bulk and true densities, and static coefficient of friction at different surfaces (mild steel and wood) by 3.58, 3.96, 6.29, 4.98, 10.72, 16.87, 1.54, 1.50, 26.23, 11.50, 7.27, and 17.86 to 23.53 %, respectively, with increase in moisture content from 47.48 to 61.4 % (w.b.). Furthermore, the angle of repose increased by 17.45 % while the porosity decreased by 3.85 % with increase in moisture content.     

Chemical Composition, Antioxidant Capacity, and Sensory Quality of Pomegranate (Punica granatum L.) Arils and Rind as Affected by Drying Method

The objective of this study was to evaluate the application of: (1) freeze drying, (2) convective drying (50, 60, or 70 °C), (3) vacuum–microwave drying (240, 360, or 480 W), and (4) a combined method of convective pre-drying and vacuum–microwave finish drying in the processing of pomegranate arils and rind. The quality parameters under study included sugars and organic acids, punicalagins and ellagic acid, total polyphenols, total antioxidant activity, and sensory quality. In general, drying led to a reduction in all studied parameters; however, the behavior of arils and rind was different. Vacuum–microwave drying at 240 or 360 W was the best drying treatment for arils, while rind required freeze drying or soft conditions of convective drying (50 °C). Further research is needed to obtain proper results with convective pre-drying and vacuum–microwave finish drying of arils and rind. With proper selection of the drying protocol, high-quality dried arils will be available for consumers; these arils will be characterized by high contents of fructose (25 g 100 g^?1), phytic acid (2.2 g 100 g^?1), punicalagins (0.57 mg g^?1), total polyphenols (1.6 mg eq gallic acid g^?1), high antioxidant capacity (0.6 mg eq Trolox g^?1), and high intensities of garnet color, sweetness, sourness, and fresh pomegranate aroma. Besides, dried rind with very high contents of active compounds (123 mg g^?1 of punicalagins and 108 mg eq gallic acid g^?1) and high antioxidant capacity (26 mg eq Trolox g^?1) will be also available as functional material.     

Design of Active Modified Atmosphere and Humidity Packaging (MAHP) for ‘Wonderful’ Pomegranate Arils

Modified atmosphere packaging (MAP) systems have been shown as beneficial to prolong postharvest life of pomegranate arils. Current application of such system is limited due to a lack of appropriate packaging films which are able to control in-package moisture condensation. Therefore, the aim of this study was to design a MAP system to balance the optimum gas composition with packaging film permeability as well as optimum in-package relative humidity (RH). The following packaging materials design were used: (i) 100% cellulose-based film NatureFlex (NF), (ii) bi-axial-oriented polypropylene (BOPP)-based film PropaFilm (PF), (iii) NF-PF (66:33%) film, and (iv) PF-NF (33:66%) film. The effects of package design on quality attributes of pomegranate arils stored at 10 °C (91?±?2% RH) for 9 days were investigated. Package design had significant (p?≤?0.05) impact in changing the in-package RH and gas composition. The 100% cellulose-based (NF) package created the lowest RH (60–66%) with highest reduction in O₂ concentration, highest total soluble solids (TSS), hardness, colour change, and high bacterial count. However, the 100% BOPP-based (PF) film resulted in highest in-package water vapour condensation and mould growth at the end of storage. The optimized packages using PF-NF and NF-PF films, respectively, maintained quality of pomegranate arils and minimized water vapour condensation. The results indicated that PF packaging film fitted with NF film window was the best to maintain the quality of pomegranate arils.     

泸型酒醅物理性质的实验研究

实验测定了酒醅含湿量、乙醇含量、真实密度、堆积密度、空隙率、堆积角和静摩擦系数在窖池中的分布规律.结果表明,随着窖池深度的增加,含湿量从60.2%升高到71.3%,乙醇含量先升高后降低,表层最低为4.1%,中下层最高为6.4%,底层为5.7%;真实密度、松散堆积密度和振实堆积密度随窖池深度增加而增大,其范围分别为747.5kg/m3～913.4kg/m3、374.7kg/m3～443.2kg/m3和529.8kg/m3～580.6kg/m3;堆积角的变化范围是42.8°～45.3°,表层最小、中下层最大;酒醅在生铁、玻璃和木板上的静摩擦系数均随窖池深度增加而增加,其范围分别为0.54～0.58、0.58～0.66和0.69～0.85.研究结果为酒醅混合搅拌及输运设备的设计和蒸馏工艺优化提供了重要参考.     

Moisture Dependent Physical Properties of Dry Sweet Corn Kernels

Physical properties of sweet corn kernels have been evaluated as a function of kernel moisture content, varying from 9.12 to 17.06% (db). In the moisture range, kernel length, width, thickness, and geometric mean diameter increased linearly from 9.87 to11.09 mm, 7.41 to 9.25 mm, 3.25 to 4.37 mm, and 6.18 to 7.62 mm, respectively, with increase in moisture content from 9.12–17.06%. The sphericity index, kernel volume, kernel surface area, and thousand seed weight increased linearly from 62.6 to 68.8, 93.8 to 194.3 mm³, 120.1 to 182.9 mm², and 220 to 268 gr, respectively. Apparent density and bulk density decreased linearly from 1.315 to 1.232 g/cm³ and 0.765 to 0.698 g/cm³, respectively, while bulk porosity increased from 41.8 to 43.3%. The highest static coefficient of friction was found on the plywood surface. The static coefficient of friction increased from 0.680 to 0.891, 0.605 to 0.741, and 0.530 to 0.644 for plywood, galvanized iron, and aluminum surfaces, respectively. The angle of repose increased linearly from 30.2 to 35.2° with the increase of moisture content.     

Soft-Seeded Pomegranate (<Emphasis Type="Italic">Punica granatum</Emphasis> L.) Varieties: Preliminary Characterization and Quality Changes of Minimally Processed Arils During Storage

A preliminary characterization of two new soft-seeded pomegranate varieties (MR-100® and KINGDOM®) based on their main physico-chemical and nutritional parameters was reported. The two varieties showed significant differences (p ≤ 0.05) in polyphenols, anthocyanins and antioxidant activity. Kingdom pomegranate had higher polyphenols (2524.73 mg GAE/L), anthocyanins (752.49 mg C₃gE/L) and antioxidant activity (EC₅₀ 13.58 μL/mL) than MR-100 (1792.74 mg GAE/L, 141.29 mg C₃gE/L and EC₅₀ 47.53 μL/mL, respectively). Moreover, minimally processed arils of the two varieties were packaged in semipermeable and micro-perforated film at 5 °C, and the quality changes that occurred during storage condition (15 days) were investigated. During storage, Kingdom arils exhibited a better performance in terms of antioxidant activity, polyphenols and anthocyanin content with respect to MR-100. Furthermore, the packaging systems did not affect the estimated quality parameters for both varieties. Based on the sensory evaluation and microbial counts, both aril varieties reached, at 15-day storage, suitable values for commercial purpose.     

不同含水量下黔江肾豆加工物理特性研究

主要研究了含水量在5.0%至35.0%范围内7个梯度水平下的黔江肾豆的各项物理特性,以期为黔江肾豆的实际生产加工、后续的开发研究及其他研究分析提供所需的籽粒物理性质数据参考。主要研究测定不同含水量下黔江肾豆的各项物理性质,包括:粒径、圆球度、体积、表面积、千粒重、容重、真实密度、孔隙率、休止角、静摩擦系数等。结果表明,除圆球度外,各项物理性质受水分含量影响均显著。随着含水量的增加,容重值降低;摩擦系数随含水量增加而增大,同时又与接触表面性质相关,木质横纹>木质直纹>钢>铝;其他各物理特性值均升高。     

Mass-Volume-Area Related and Mechanical Properties of Soybean as a Function of Moisture and Variety

Selected physical properties of three varieties of soybean were determined within a moisture content range of 6.25 to 11.60% dry basis. The seed length, width and thickness for the three varieties increased with the increase in moisture content while the sphericity and roundness of the three varieties increased within the range of 43.0 to 72.3% and 45.5 to 75.9% respectively. True density, bulk density and porosity decreased with increase in moisture content within the range of 1203 to 964 kgm^?3, 809 to 740 kgm^?3 and 0.35 to 0.22. The coefficient of friction also decreased with increase in moisture and the highest and lowest value was 23.7 and 17.3 on plywood while that on glass was 19.8 and 11.6, respectively. The angle of repose and terminal velocity increased within the range of 10.2° to 15.3° and 10.10° to 12.60 m/s for the varieties. The compressive force however decreased and the highest and lowest value was 12.85 and 3.5 N respectively for the three varieties.     

Physico-chemical Properties, Vitamin C Content, and Antimicrobial Properties of Pomegranate Fruit (Punica granatum L.)

Pomegranate (Punica granatum L.) fruit is widely used in the food and process industries due to its excellent nutritional and health value and as a raw material for the manufacture of secondary products such as jellies, dyes, and cosmetics. The objectives of this research were to determine the vitamin C content and antimicrobial properties of fresh and dried fractions of fruit peel and arils of locally grown and imported pomegranate in Oman. A significant variation in vitamin C content was found among the five varieties of pomegranate studied, ranging from 52.8 to 72.0 mg/100 g fresh weight (fw) for arils and 76.8 to 118.4 mg/100 g fw for peels. Irrespective of the variety of pomegranate, vitamin C content in the peel was significantly higher than the aril, with differences ranging from 24.4% to 97.0% depending on variety. Fruit fractions showed antimicrobial effects (inhibition zone) on Staphylococcus aureus and Pseudomonas aeruginosa but not Escherichia coli. Sun drying of fruit peel significantly (p ≤ 0.05) enhanced vitamin C retention and antimicrobial effects in comparison with oven drying presumably due to lower rate of moisture removal associated with low temperature drying over longer duration in comparison with short-time high-temperature oven drying.     

Physical properties of barley and oats cultivars grown in high altitude Himalayan regions of India

In this study, some selected physical properties of oats and barley viz seed size, shape, gravimetric properties, density characteristics, angle of repose, static coefficient of friction and terminal velocity were determined at a constant moisture content of 8.0 %. These properties are often required for designing of food processing appliances. The average of the principle diameters was found to be 4.96 ± 0.50, 5.34 ± 0.31, 6.00 ± 0.26 and 5.41 ± 0.44 mm and 1,000-grain weight was 41.9 ± 0.2, 40.06 ± 0.02, 36.66 ± 0.01 and 36.51 ± 0.02 g for hulled barley, hulless barley, Sabzaar oats and SkO-20 oats, respectively. The grains were narrow and elongated having an average sphericity of 50.55 ± 3.7, 47.923 ± 1.8, 32.578 ± 1.3 and 35.69 ± 2.1 %, respectively. The physical properties of the flours like angle of repose, flowability, bulk and true density were also determined. The value of angle of repose was found to be 50.44 ± 0.27⁰, 63.45 ± 0.34⁰, 46.86 ± 0.25⁰ and 44.49 ± 0.10⁰ for the flour of hulled barley, hulless barley, oats Sabzaar and SKO-20, respectively. The flours had poor flowability having a compressibility index of 33.69 ± 0.12, 34.32 ± 0.87, 27.94 ± 1.23 and 27.5 ± 0.74 and Hausner’s ratio 1.58, 1.52, 1.38 and 1.37, respectively.     

PHYSICAL AND AERODYNAMIC PROPERTIES OF MAKHANA

Makhana is a popped kernel of gorgon nut (Euryale ferox) and is considered a delicious food item in India. It is, presently, sorted, graded and processed manually. To develop any kind of mechanized system for these purposes, physical data are required and thus, test weight, bulk density, true density, porosity, angle of repose and coefficient of friction of different grades of makhana were determined using standard techniques at moisture contents ranging from 5 to 20% (dry basis). The data were used to develop correlation equations that predict these physical properties as a function of moisture content of makhana. The spatial dimensions and aerodynamic properties were also determined. The average diameter of makhana varied between 18.4 mm to 12.4 mm with the sphericity between 0.581 to 0.967; and other physical properties varied quadratically with moisture content. The terminal velocity and drag coefficient of makhana at 8% moisture content (dry basis) varied between 4.48 to 6.10 m/s and 0.62 to 1.06, respectively.     

Optimisation of processing variables affecting the osmotic dehydration of pomegranate arils

For the optimisation of osmotic dehydration by response surface methodology, the experiments were conducted according to Central Composite Rotatable Design (CCRD) with three variables at five levels. The low and high levels of the variables were 40 and 50 °C for osmotic solution temperature, 45 and 55°Bx for sucrose solution concentration, 60 and 100 min for duration of dipping in osmotic solution, respectively. The fruit to solution ratio was kept 1:4 (w/w) during all the experiments. Before dipping the arils in sucrose solution, the freezing of the whole pomegranate at ?18 °C was carried out to increase the permeability of the outer cellular layer of the arils. The arils were further convectively dehydrated at 60 °C air temperature up to final moisture content of 10% (wb) to make it a shelf stable product. The optimum conditions for osmotic solution concentration, temperature and process duration were 55°Bx, 40 °C and 100 min, respectively.     

Conventional kiln drying and equalization of Western hemlock (<Emphasis Type="Italic">Tsuga heterophylla</Emphasis> (Raf.)[Sarg]) to Japanese equilibrium moisture content

Density sorted, matched-samples of Western hemlock were dried in order to quantify the physical changes of conventionally kiln dried wood when exposed to the equilibrium moisture contents of a typical Japanese winter. Physical changes were monitored for 14 weeks by sampling board weight, dimensions, shell and core moisture contents (oven-dry basis) and warp. The difference of 7% in equilibrium moisture content between Tokyo and Vancouver is large enough to elicit a response in shell moisture content, dimensions and warp. However, the responses found should be expected when wood is examined in context of its natural variability. Drying 105 mm by 105 mm Western hemlock to 19% moisture content at the core should be considered the maximum target moisture content. A target moisture content of 15% at the core would balance drying time and end-use stability as the lumber is equalized to Japanese conditions.     

基于主成分分析的豆粕物理特性评价

为对豆粕的物理特性进行分析及量化评价,本文以42个豆粕样品为试验材料,测定分析其水分、容重、热物理特性、摩擦特性及粉碎特性指标参数,并运用主成分分析法简化物理特性指标,构架评价体系,得到每种样品的综合得分。结果表明,样品各物理特性指标之间存在不同程度的相关性,其中比热与水分和热传导系数呈显著正相关,与热扩散系数、休止角和摩擦系数呈极显著负相关;热传导系数与热扩散系数呈显著正相关,与休止角和摩擦系数呈极显著负相关;热扩散系数与容重呈显著负相关;摩擦系数与水分呈显著正相关,与容重和休止角呈极显著正相关;平均粒径与水分呈显著正相关,与休止角呈显著负相关。通过主成分分析提取了前4个主成分,累积方差贡献率达到88.898%(85%),能够代表原来8个物理特性指标中的绝大部分的信息,并得到评价公式Z=0.363Z_1+0.234Z_2+0.150Z_3+0.142Z_4,计算出豆粕物理特性指标综合得分。     

Physical,physicochemical and anti-nutritional properties of Horse Chestnut (<Emphasis Type="Italic">Aesculus indica</Emphasis>) seed

The aim of the study was to investigate the physical, physicochemical and anti-nutritional properties of Horse Chestnut (HCN) seed. The average length, width and thickness of the seeds were 4.70, 4.00 and 3.20 cm, respectively. Geometric and arithmetic mean diameter were 3.92 and 3.97 cm. Average sphericity and aspect ratio of the seeds were 83.40 and 85.11 %, respectively. The true density, bulk density, density ratio and porosity values of the seeds were 1072, 518 g/cm³, 48.32 and 51.68 %, respectively. The angle of repose for the seeds obtained on plywood, mild steel, stainless steel and galvanized sheet was 22.30°, 20.30°, 18.30° and 22.79° respectively. The coefficient of static friction of the seeds obtained on plywood, mild steel, stainless steel and galvanized sheet was 0.54, 0.52, 0.51 and 0.52, respectively. The average force required to break the seed was 328 N. The L ^* , a ^* , and b ^* color values of seed flour were found to be 92.07, 3.47 and 13.70 respectively. Proximate composition of the seed flour revealed 10.71 % moisture, 3.16 % ash, 6.34 % crude fibre, 3.27 % fat, 6.78 % protein, 69.74 % carbohydrate, 10.15 % sugar and 59.59 % starch and energy value of 327.51 cal/100 g. Anti-nutritional factors of the seed flour were determined in terms of oxalate, phytate, tannin and saponin. Pre-treatments including soaking and microwave heating showed significant reduction of anti-nutritional factors of the seed flour. Microwave heating at 2450 MHz for 2.5 min showed higher reduction of 95.45, 91.66, 68.15 and 87.20 % in oxalate, phytate, tannin and saponin content respectively. Knowledge of physical properties of HCN seeds can be useful in designing equipment for postharvest handling and processing operations. Pre-treatments for reduction of anti-nutritional components of the seeds can be helpful for utilization of HCN seed in different food formulations.     

Effects of species and moisture content on penetration of liquid in laser incised lumber by the passive impregnation method

Penetration of liquid by passive impregnation method for Douglas-fir (Pseudotsuga menziesii Franco), sugi (Cryptomeria japonica D. Don) and Japanese larch (Larix leptolepis Gordon) was studied. Effects of initial moisture content of sugi (16, 43 and 70% moisture content) on liquid penetration were also studied. Dried Douglas-fir (mc=14%) and sugi (mc=16%), and green Japanese larch (mc=45%) and sugi (mc=70%) were treated by passive impregnation method for penetration analysis. It was observed that dried sugi had the highest level of liquid penetration both in length (170 mm) and width (8 mm) for all measured sections followed by green sugi, green Japanese larch and dried Douglas-fir. In case of different initial moisture content, the highest absorption (624 kg/m³) and penetration (maximum 87 and 96% at cross and longitudinal surfaces, respectively) was observed for sugi having the lowest initial moisture content under the same passive impregnation conditions. Absorption and penetration decreased with the increase of initial moisture content for sugi. These results could help in designing incising pattern and density, as well as solving the problems related to high initial moisture content of wood for passive impregnation.     

Non-destructive evaluation of grain angle, moisture content and density of spruce with microwaves

Non-destructive evaluation of the physical properties of wood is a key task in modern wood manufacturing processes. Due to a rapidly increasing production speed, fast, non-contacting, reliable and robust measurement systems are demanded by the wood industry. Common moisture meters are able to reasonably cope with industrial needs. However, modern detection of wood grain angle deviation remains an unresolved issue. Microwave technology features the ability to simultaneously identify grain angle, density and moisture content of wood by measuring attenuation, phase shift, and depolarization of transmitted signals. This paper reports on series of microwave measurements revealing the desired physical properties for spruce. Samples were tested at different frequencies in the range from 8 to 12 GHz. For each frequency the grain angles were identified with standard errors of maximum 0.15° (measuring range from ?90° to +90°). Standard errors in the determination of moisture density were less or equal 1.8 kg/m³ (measuring range from 27 to 56 kg/m³). Standard errors determining moisture content were maximum 0.47 % (measuring range from 7.6 to 14 %), and standard errors for dry density were maximum 11.3 kg/m³ (measuring range from 284 to 492 kg/m³).