Effect of micronisation and electromagnetic radiation on physical and mechanical properties of Canadian barley

The effect of micronisation (high‐intensity infrared heating) and microwave radiation of normal barley (NB), high‐amylose barley (HAB) and waxy barley (WB) on the physical and mechanical properties was studied. Samples were tempered to 42–45% moisture content and then subjected to infrared or microwave radiation to reduce the moisture content to approximately 10%. The grain surface temperature during radiation was maintained at 100 °C. The changes in physical and mechanical properties were compared with unprocessed samples. Thermal radiation increased slightly the volume of the kernels because of the diffusion of water vapour from inside to the outer surface. These changes resulted in a decrease in particle and bulk densities. Thermal radiation affected the Hunter colour values, as well. The mechanical properties including bio‐yield point, modulus of elasticity and breakage susceptibility were affected by micronisation and microwave heating.     

Effect of maturation on nutrient composition of selected vegetable legumes

Five legume vegetables harvested at the immature green and mature stages were analysed for weight and nutrient composition. In some types the seed weight increased up to seven-fold in the last 10 days of maturation. The protein, fat, carbohydrate and thiamin contents increased on maturation. However, the proportional increase varied widely from 10 to 100 % in the case of protein and carbohydrates. The changes observed in the nutrient composition and weight of vegetable legume seeds in the last 10 days of maturation suggest that it is advantageous to harvest vegetable legumes when mature.     

Effect of rice wax on water vapour permeability and sorption properties of edible pullulan films

Edible films were prepared using various ratios of pullulan and rice wax. Freestanding composite films were obtained with up to 46.4% rice wax. Water vapour barrier properties of the pullulan film were improved with increased addition of rice wax. Moisture sorption isotherms were also studied to examine the impact of rice wax on the water sorption characteristics of the film. The Brunauer–Emmet–Teller (BET) and Guggenheim–Anderson–de Boer (GAB) sorption models were tested to fit the experimental data. The models gave a good fit up to the water activity (a_w) of 0.55 for BET and a full range of a_w from 0.12 to 0.95 for GAB (R² ? 0.98). Changes in the sorption parameters, particularly such as the decrease in monolayer moisture content (Mo), reflect the trend of reduced hydration capacity with increased addition of rice wax, providing useful information on water activity conditions to achieve stability for the composite films.     

Evaluation of percentage oil yield,energy requirement and mechanical properties of selected bulk oilseeds under compression loading

The present study examined the percentage oil output, energy and mechanical properties of selected bulk oilseeds namely pumpkin, hemp, sesame, milk thistle, cumin and flax by a uniaxial compression process of a maximum load capacity of 500 kN and a preset speed of 5 mm/min. Each sample was measured at 60 mm pressing height with a plunger using the pressing vessel of diameter 60 mm. The results show that milk thistle seeds required the highest force corresponding to the highest stress and energy demand for recovering the oil in both the bulk oilseeds and seedcakes. However, pumpkin seeds produced the maximum residual oil yield of 24.99 ± 0.04%, followed by sesame seeds at 21.29 ± 1.82% and then flax seeds at 22.61 ± 0.31%. The study revealed that higher energy is required to produce the maximum oil yield with minimum residual oil in the seedcake by continuous pressing.     

动态水分吸附法研究发酵饼干水分吸附特性

以发酵饼干为研究对象,采用动态水分吸附法研究发酵饼干在25℃的水分吸附等温线与水分吸附动力学特性,同时与饱和盐溶液法得到的水分吸附等温线进行对比,并基于常用的等温吸湿模型对实验数据进行拟合。结果表明:动态水分吸附仪能在更短的时间里采集更多的数据,高频率的实时数据采集能够更准确地获得食品的水分吸附动力学特性;其从水分活度适用范围和拟合精度方面来看,GAB模型拟合饼干的等温吸湿的效果最佳。与饱和盐溶液法结果相比,动态水分吸附法得到的饼干平衡含水率略低。      

Influence of roasting conditions on the acrylamide content and the color of roasted almonds

ABSTRACT:  The influence of roasting conditions on the acrylamide content and on the color of roasted almonds of 3 cultivars was investigated. The temperature inside the almond kernel, the water content, the color, and the acrylamide content were determined at different roasting temperatures and times. The formation of acrylamide started only when the kernel temperature had exceeded approximately 130 °C. The activation energy for the acrylamide formation during the roasting of almonds was 123 kJ·mol⁻¹. The color as measured by the degree of brightness correlated well with the acrylamide content as acrylamide content increased with increasing darkness. Therefore, control of roasting temperature presents the critical factor for limiting the acrylamide concentration in the final product. At constant roasting conditions, almonds with higher initial moisture content contained less acrylamide after roasting, which is probably due to the influence of moisture on the development product temperature during roasting.     

Effect of accelerated aging on selected physical and mechanical properties of Bambusa rigida bamboo

Bambusa rigida bamboos were subjected to accelerated aging test, and the main physical and mechanical properties before and after aging were comparatively investigated. The results revealed that the aged bamboos lost parts of their original physical and strength properties. Furthermore, mechanical strength properties and basic density of both control and aged specimens increased significantly with the height of the culms, while that for the volumetric shrinkage was reverse. The effect of accelerated aging on the properties of base portion specimens was much more significant than that of the middle and top portions.     

Effect of pre-dehulling treatments on some nutritional and physical properties of navy and pinto beans (Phaseolus vulgaris L.)

The effect of pre-dehulling treatments using low and high temperatures on some nutritional and physical properties of navy and pinto beans was investigated. Beans were exposed to water (14%, 28% and soaking 1:5, w/v for 6 h, 16 and 16 h, respectively) to facilitate seed coat detachment prior to freeze drying (FD) for 48 h or heat drying (HT) for 20 or 60 min. Exposure to the highest moisture levels produced the largest seed coat yields (17.38-20.91%) and was independent of the drying conditions. The total phenolic content was positively correlated to the 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidant activity and increased as the exposure time to HT increased, but it was unaffected by the FD. The nutritional properties of the bean varieties differed significantly, phytic acid was unaffected, and the highest antioxidant activity was observed on the seed coats of HT pinto beans (69.24-84.46% of DPPH discoloration). Significant physical changes were observed for the HT seeds, with the highest yellowness and the lowest peak viscosity detected in the soaked and HT (60 min) beans.     

Water sorption and cooking time of red kidney beans (Phaseolus vulgaris L.): part I – Effect of freezing and drying conditions on water sorption and cooking time

Water sorption and cooking time of kidney beans were determined. The beans were manually harvested at 19.2 ± 0.1% moisture content and stored at ?20 and ?10 °C for about half a year. The beans were further dried at 30, 40 and 50 °C inside a thin‐layer drier for 7.5 h or under room conditions for 4 week. The freezing storage temperature before the beans were dried did not influence their cooking time and water sorption. The saturated kernel volumes decreased approximately 7% after drying. The beans decreased their sphericity during water sorption and had a larger swelling ratio in the thickness direction than in other directions. Lower initial moisture content, especially with a higher drying temperature, decreased water sorptivity and resulted in higher percentage of uncooked kernels if the beans were not soaked before cooking. However, there was no relationship between initial moisture content and uncooked percentage if the beans were soaked before cooking. High drying temperature resulted in hard‐to‐cook (HTC) phenomenon.     

Impact of Almond Form and Moisture Content on Texture Attributes and Acceptability

The objectives of this study were to measure sensory texture attributes of 5 types of almonds (blanched slivered, natural sliced, whole blanched, whole dry roasted, and natural whole) conditioned at 4 different moisture levels, to measure liking of a subset of these products, and to compare the sensory texture measurements with consumer liking ratings. Thirteen panelists trained to evaluate almond texture rated the texture attributes of the 20 almond samples. A panel of 113 almond consumers rated their liking of a subset of 8 of these almonds. Compared with the whole almonds, sliced and slivered almonds had less hardness, less crunchiness, less cohesiveness, less tooth packing, and required fewer chews and swallows to consume. Compared with slivered almonds, sliced almonds were more powdery, had more surface roughness, more loose particles, and were crisper. Compared with slivered almonds, sliced almonds were less hard, broke into fewer pieces, had less moistness and cohesiveness of mass, less fatty film, and required fewer chews and fewer swallows to consume. Dry roasted almonds were generally harder, more crisp, more crunchy, and produced more loose particles than natural almonds, which were, in turn, more hard, crisp, and crunchy than blanched almonds. As moisture content increased, moistness of mass and cohesiveness of mass increased. Crispness, number of pieces, hardness, crunchiness, persistence of crunch, and particulate mass decreased with increasing moisture content. Consumer texture liking ratings were highly positively correlated with the attributes crispness, crunchiness, and persistence of crunch.     

Crystallisation and moisture sorption properties of selected Australian unifloral honeys

The sorption properties of yapunyah (Eucalyptus ochropholia) and yellow box (Eucalyptus melliodora) honeys (Australian unifloral honeys) were investigated in a controlled relative humidity (RH) environment at 30 °C for 71 days. The original water activity of the honeys affected the sorption properties. These two honeys absorbed moisture at and above 67.9% RH and desorbed moisture at and below 51.4% RH. The crystallisation behaviour of tea tree (Melaleuca quinquenervia) and yapunyah honeys was studied during storage at 13 and 23 °C. The degree of crystallisation was monitored by measuring the absorbance at 660 and 665 nm using a spectrophotometer. The heat‐treated honeys did not show any sign of crystallisation after 5 months, whereas a seeding with precrystallised honey induced crystallisation of the same honeys. This crystallisation was more rapid at 13 than at 23 °C. Copyright © 2003 Society of Chemical Industry     

马铃薯全粉平衡水分吸附等温线与吸附等热研究

采用静态称重法在温度10～35℃、相对湿度11%～96%范围内测定了五种马铃薯全粉的平衡水分/平衡相对湿度(EMC/ERH)数据,确定了多项式方程、修正3参数Guggenheim-Anderson-de Boer(MGAB)、修正Halsey(MHAE)、修正Oswin(MOE)为适合的等温线拟合方程,采用多项式EMC方程分析马铃薯全粉的安全储运最大允许的含水率,在25℃、RH60%条件下,绝对安全水分是10.05%;在25℃、RH 70%条件,相对安全水分是12.64%。采用MHAE分析马铃薯全粉水分吸附等热,随着含水率增加到17.5%,马铃薯全粉水分吸附等热则以抛物线形式快速地减少,之后随着含水率增加,水分吸附等热则减少缓慢。在含水率22%,马铃薯全粉水分吸附等热接近纯水的吸附等热。     

超声波辅助法提取芸豆种子黄酮类化合物研究

采用超声波辅助法提取芸豆种子黄酮类化合物。进行四因素三水平正交试验,用紫外-可见分光光度计测量各处理黄酮类化合物含量。通过极差分析,超声波辅助法提取芸豆种子黄酮类化合物的最佳条件为:乙醇体积分数为50%、提取温度为35℃、提取时间60 min、液料比40∶1(mL/g)。     

Effect of temperature and initial moisture content on sorption isotherms of banana dried by tunnel drier

Sorption isotherms of intermediate moisture content (IMC) products are essential to predict shelf-life of packaged moisture-sensitive product by modelling moisture uptake during storage and distribution. The effect of temperature and initial moisture content (MC) of IMC banana on the relationship between MC and water activity were investigated. Raw bananas were dried in a tunnel dryer at 2% relative humidity (RH), 70 °C, and a 3.2 ± 0.2 m s^–1 air velocity. Drying procedure was carried out a number of times until various IMC levels were obtained (5%, 14%, 22% and 33% db for banana). Sorption isotherms of bananas were determined at 10, 20, 30 and 40 °C. The initial MC of IMC banana had no significant effect on the relationship between MC and water activity according to statistical analysis. All the sorption curves were found to be Type II. BET, GAB, modified GAB, Oswin, Halsey and modified Freundlich models were fitted to the data and it was found that the best results were obtained with a modified Freundlich equation. A secondary modified Freundlich model was built accounting for the effect of a _w and temperature on the sample MC.     

Effect of processing on antioxidant contents in selected dry beans (Phaseolus spp. L.)

Dry beans are rich sources of dietary fiber and phytochemicals such as flavonoids and phenolics. In the current study, we determined the effects of two processing methods (soaking and toasting) on total phenolics, flavonoids, proanthocyanidin and antioxidant potential by 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity and ferric reducing antioxidant potential (FRAP) in selected dry beans (red kidney beans (K), black-eyed peas (B), pinto beans (P) and soy beans (S)).Total phenolics (mg/g dwb) expressed as gallic acid equivalents (GAE), total flavonoids (mg/g dwb) as catechin equivalents (CE) and proanthocyanidin expressed as leucocyanidin equivalent (mg LE/g) ranged from 3.42 to 7.21, 0.61 to 0.84 and 0.51 to 3.13 in raw beans; 3.58 to 6.94, 0.19 to 0.99 and 0.43 to 3.13 in soaked beans and 4.55 to 9.52, 0.23 to1.00 and 0.20 to 3.25 in toasted beans, respectively.FRAP (μg/g) in raw, soaked and toasted dry beans ranged from 0.00097 to 0.00424 while DPPH_(T30) (%) ranged from 43.9 to 62.61.Our results indicate that processing methods (soaking and roasting) influenced total phenolic, flavonoid and antioxidant contents (DPPH, FRAP) in selected dry beans.     

Effect of osmotic pretreatment on equilibrium moisture content of dehydrated carrot cubes

The equilibrium moisture contents were determined for carrot cubes osmotically pretreated in salt, sucrose and salt plus sucrose combined solution using static method at 10, 25, 40 and 50 °C over a range of relative humidities from 14% to 95%. Six isotherm equations were applied for analysing the experimental data. Modified exponential equation, is the best equation for predicting the equilibrium moisture contents (EMC) of the dehydrated carrot cubes preosmosed in salt and sucrose plus salt solution, whereas modified Hasley equation is suitable for dehydrated carrot cubes preosmosed in sucrose solution over the relative humidity range of 14–95%. The EMC of carrot cubes osmotically pretreated with salt was highest among all pretreatments, and was lowest for un‐osmosed samples.     

Moisture dependence on mechanical properties of pine nuts from Pinus pinea L.

Mechanical properties of pine nut shell are very important in the cracking process. Before industrial cracking shell moisture is adjusted by water soaking in order to avoid the breaking up of the nuts. In this work the moisture dependence of the mechanical properties of pine nut shells were studied in order to improve the industrial cracking process.