Production of Peanut Flour from Microwave Vacuum-Dried Peanuts

Defatted peanut flours with significantly reduced raw peanut taste and nitrogen solubility of 85+% were produced from field Runner peanuts that had been microwave-vacuum-dried to maximum temperatures of 80°C and 96°C. The flours were prepared from 4.54 kg of peanuts, dried from 25.5% to less than 10% moisture, at 375 Torr absolute pressure and at 1400 and 813 watts microwave power (2450 MHZ). Peanut temperature at end of drying significantly affected the intensity of the raw peanut flavor. Storage at 23.9°C for 14 months had no significant effects on intensity of the raw peanut flavor. Hexane extraction of blanched peanut kernels showed that mass velocity percolation rates increased with increase in final drying temperature of peanuts.     

Changes of microwave structure/dielectric properties during microwave freeze‐drying process banana chips

This experimental study investigated the trend of structure and dielectric properties during microwave freeze‐drying process banana chips. The mass of banana samples was 160 g, the microwave power set as 2 W g^?1 and the highest drying temperature set as 55 °C. The whole drying process can be finished within 6 h. A network analyser and light microscope were used to determine the dielectric properties and structure. The dielectric properties, ε′ (from 20.80 to 1.20) and ε′′ (from 7.74 to 0.15), and the size of cell get smaller as the drying process continues, especially during the 3–4 h drying, which is the end of primary drying stage and the beginning of secondary drying stage. The trend of dielectric properties and microstructure of samples during drying can be an exact indication of drying stage of MFD.     

A novel dielectric drying method of sea cucumber

The sea cucumber autolyses readily so it must be dehydrated for preservation. Traditional drying methods of sea cucumber need very long time and have adverse effect on quality. Hence, a novel microwave freeze drying technique was developed to dry sea cucumber. Because microwave heating is a function of dielectric properties of the material in microwave field, dielectric properties of sea cucumber were determined. As expected, the dielectric loss factor of sea cucumbers was very low in frozen state, and several pretreatments (nanoscale calcium carbonate impregnation and vacuum impregnation, salt impregnation, etc.) were analysed to improve the dielectric properties of sea cucumber. Vacuum impregnation with nanoscale calcium carbonate combined with microwave freeze drying was found to be an efficient drying method for sea cucumber by anova (P < 0.01). Compared with microwave freeze drying method without any treatments, this drying method could reduce the drying time by up to two hours.     

Predictive equations for the dielectric properties of foods

Variations in the dielectric properties of foods with applied microwave frequencies, and food composition, moisture content and temperature, were investigated. A series of equations to estimate the dielectric properties of a wide range of food materials was deduced from available experimental data and current understanding. the equations are suitable for incorporating into a numerical model to predict the transient temperature and moisture-content profiles within microwave-heated foods.     

THERMOELECTROMAGNETIC COUPLING IN MICROWAVE FREEZE-DRYING

A coupled thermoelectromagnetic model of microwave freeze‐drying was developed by introducing the reflection coefficient method of the electromagnetic theory into the sublimation‐condensation model, to describe the coupling between the electromagnetic field strength distribution and the heat and mass transfer in microwave freeze‐drying. The experiments of beef were provided and the good agreement between the predicted and experimental results validates the model. The variations of the field strength, the temperature and the moisture content distributions during the microwave freeze‐drying process were discussed based on the model. The simulated results show that the microwave distribution in the cavity is a moving standing wave and that the actual field strength inside the material is less than that in the cavity. The nonuniform heating of the microwave will increase either the temperature in the dried region or the temperature in the frozen region, depending on the microwave input direction.     

Impact of roasting conditions on the quality and acceptance of the peanut paste

Roasting is the main processing step performed to improve sensory and conservative properties of peanuts. The objective of this study was to evaluate changes in peanut oil and paste during roasting at different temperatures in a conventional oven (80, 110, 140, 170, and 200°C) and microwave. The increase in roasting temperature promoted reduction of L* value, b* value, and increases of a*, K₂₃₂, K_270, and acidity. For alpha (α), gamma (γ), and delta (δ) tocopherols, as well as fatty acids, less degradation were observed at the roasting temperature of 140°C. Paste acceptability greater than 70% was achieved with roasting at 140°C. Based on the results, 140°C was the optimal roasting temperature that achieved the best paste acceptance rates with the smallest changes in oil and tocopherol quality parameters.     

Dielectric Properties of Sweet Potato Purees at 915 MHz as Affected by Temperature and Chemical Composition∗

A process for rapid sterilization and aseptic packaging of sweet potato puree using a continuous flow microwave system operating at 915 MHz has been successfully developed. In microwave processing, dielectric properties have a major role in determining the interaction between purees and the electromagnetic energy. The objective of this research was to determine how dielectric properties are affected by temperature and chemical composition of purees derived from thirteen sweet potato cultivars with varying flesh colors. Results indicated that temperature, moisture, sugar and starch content had a pronounced effect (p < 0.001) on dielectric properties measured from 15°C to 145°C at 915 MHz. Dielectric constant decreased with increasing temperature, while dielectric loss factor increased quadratically. Power penetration depth of all cultivars decreased with increasing temperature. Predictive equations were developed for dielectric constant (R²?=?0.82) and dielectric loss factor (R²?=?0.90) as a function of temperature, moisture, sugar, and starch. The predictive equations would be useful in determining the dielectric properties of sweet potato purees for the microwave processing technology.     

Multiphysics Modeling of Microwave Heating of a Frozen Heterogeneous Meal Rotating on a Turntable

A 3‐dimensional (3‐D) multiphysics model was developed to understand the microwave heating process of a real heterogeneous food, multilayered frozen lasagna. Near‐perfect 3‐D geometries of food package and microwave oven were used. A multiphase porous media model combining the electromagnetic heat source with heat and mass transfer, and incorporating phase change of melting and evaporation was included in finite element model. Discrete rotation of food on the turntable was incorporated. The model simulated for 6 min of microwave cooking of a 450 g frozen lasagna kept at the center of the rotating turntable in a 1200 W domestic oven. Temperature‐dependent dielectric and thermal properties of lasagna ingredients were measured and provided as inputs to the model. Simulated temperature profiles were compared with experimental temperature profiles obtained using a thermal imaging camera and fiber‐optic sensors. The total moisture loss in lasagna was predicted and compared with the experimental moisture loss during cooking. The simulated spatial temperature patterns predicted at the top layer was in good agreement with the corresponding patterns observed in thermal images. Predicted point temperature profiles at 6 different locations within the meal were compared with experimental temperature profiles and root mean square error (RMSE) values ranged from 6.6 to 20.0 °C. The predicted total moisture loss matched well with an RMSE value of 0.54 g. Different layers of food components showed considerably different heating performance. Food product developers can use this model for designing food products by understanding the effect of thickness and order of each layer, and material properties of each layer, and packaging shape on cooking performance.     

花生荚果干燥技术及设备的研究现状与发展

花生作为世界重要的油料之一,在农作物中占据举足轻重的地位.刚收获的新鲜花生荚果由于水分较高易受到多种因素影响而导致霉变并产生黄曲霉毒素,从而影响使用安全并降低花生的经济价值.花生荚果收获后及时干燥可有效抑制微生物和霉菌的生长及繁殖,降低环境温湿度对花生储藏的影响,更大限度的保证花生的品质和使用安全.归纳了国内外花生荚果...     

Microwave vacuum drying of osmotically dehydrated mandarin cv. (Sai‐Namphaung)

Mandarin [mandarin cv. (Sai‐Namphaung)] was subjected to osmotic dehydration prior to microwave vacuum drying. Osmotic solutions were varied using different ratios of sucrose to glycerol (9:1, 7:3 and 5:5 w/w). Because of the decreased moisture content and solid gain during osmotic dehydration, dielectric properties of mandarin were changed significantly (P ≤ 0.05). The osmotically dehydrated mandarin was then dried further using microwave vacuum drying at 4.8 and 6.4 W g^?1. Among thin layer models, page model was the best to describe the drying of osmotically dehydrated mandarin. An increase in the microwave power could increase drying rate without significant effect on hardness of dried samples. Nonetheless, the hardness was significantly (P ≤ 0.05) reduced by an increase in the glycerol ratio in the osmotic solution. The increase in microwave power and glycerol ratio significantly (P ≤ 0.05) decreased β‐carotene content and thereby affected colour of the dried mandarin.     

Peanut polyamines may be non‐allergenic

Polyamines such as putrescine, spermidine and spermine have been implicated in preventing food allergies in early life, but they have also been reported to be able to bind to immunoglobulin E (IgE) antibodies in vitro (ie they are possibly allergenic). The objective of this study was to determine if polyamines bind in vitro to IgE antibodies from a pooled serum of five peanut‐allergic individuals. Levels of polyamines were also determined by ion‐exchange chromatography. Indirect and inhibition enzyme immunosorbent assays (ELISAs) were used to determine the IgE binding or allergenic properties of polyamines. Results showed that, of the three polyamines, spermidine was predominant in peanuts. In both indirect and inhibition ELISAs, IgE antibodies did not bind to the polyamines. It was concluded that polyamines from peanuts, unlike peanut proteins, are not allergenic or an additional threat to patients who are allergic to peanuts. Published in 2005 for SCI by John Wiley & Sons, Ltd.     

A SPECIFIC QUALITATIVE DETECTION METHOD FOR PEANUT (ARACHIS HYPOGAEA) IN FOODS USING POLYMERASE CHAIN REACTION

A qualitative method for detection of peanuts in foods using polymerase chain reaction was developed. A universal primer pair CP 03‐5′/CP 03‐3′ was designed to confirm the validity of the DNAs for PCR. The plant‐specific amplified fragments were detected from 13 kinds of plants using the universal primer pair. In addition, for the specific detection of peanuts with high sensitivity, the primer pair agg 04‐5′/agg 05‐3′ was designed to detect the gene encoding the peanut agglutinin precursor. The primer pair specifically generates a 95‐bp amplified fragment from peanut genomic DNA. Five hundred femto grams of peanut genomic DNA can be detected using the established method. The same qualitative results were obtained from both model processed and nonprocessed food samples containing 0.001, 0.01 and 0.1% of peanut. Moreover, it was shown that the trace amount of peanut in the commercial food products could be qualitatively detected using this method. The reproducibility and applicability of the proposed methods were verified in a six‐laboratory collaborative study.     

Composition, stability and acceptability of different vegetable oils used for frying peanuts

The purpose of this work was to determine the chemical stability of vegetable oils in the frying process and the consumer acceptance of fried-salted peanuts prepared in different vegetable oils. Fatty acids composition was determined in sunflower, corn, soybean, peanut and olive oils. A chemical study (free fatty acid and p-anisidine values) of these oils at frying temperature (170 °C) was developed during 96 h. Consumer test of fresh products was performed on fried-salted peanuts prepared in the different oils. Peanut oil and virgin olive oil presented oleic acid as predominant fatty acid (44.8% and 64.2%, respectively), making it more resistant to lipid oxidation at frying temperature than the other refined vegetable oils (sunflower, corn and soybean oils). Virgin olive and peanut oils showed less increment of free fatty acids and p-anisidine value than the other oils along the heating essay. In addition, fried-salted peanuts prepared with refined peanut oil showed higher consumer acceptance than those prepared with other vegetable oils such as sunflower, corn, soybean and olive oils. Peanut oil could be used to fry peanuts obtaining products with higher consumer acceptance and shelf-life, thus preventing loss of their sensory and nutritional quality.     

Mathematical Modeling and Simulation of Microwave Thawing of Large Solid Foods Under Different Operating Conditions

Microwaves require shorter times to increase foodstuffs temperature when compared to conventional heating methods. However, there are some problems associated to temperature distribution within the products, owing to the preferential absorption of electromagnetic energy by liquid water, caused by differences between its dielectric properties and those of ice (“runaway”). To analyze the behavior of food microwave thawing, a mathematical three-dimensional (3D) model was developed by solving the unsteady-state heat and mass transfer differential equations; this model can be applied to large systems for which Lambert’s law is valid. Thermal, mass transport, and electromagnetic properties varying with temperature were used. The numerical solution was developed using an implicit Crank–Nicolson finite difference method using the classical formulation for one-dimensional (1D) systems and the alternating direction method in two and three dimensions. The model was validated using experimental data from the literature for 1D and two-dimensional conditions and with experiments performed in our laboratory for 3D heat transfer using frozen meat. It was applied to predict temperature and water concentration profiles under different thawing conditions in meat products and to simulate the effect of a fat layer located at the surface of the meat piece on temperature profiles. For different product sizes in rectangular geometry, numerical simulations demonstrated that microwave thawing times were significantly lower in comparison to conventional thawing methods. To prevent overheating during thawing, the combination of continuous microwave power with simultaneous application of air convection and the application of microwave power cycles, using refrigerated air convection with controlled surface temperature, were analyzed.     

微波提取花生茎中水溶性膳食纤维的工艺优化

以花生茎为原料,微波提取花生茎中水溶性膳食纤维。通过对浸泡时间、微波时间、微波功率、微波温度和料液比等影响因素进行单因素及正交试验,获得花生茎水溶性膳食纤维的最佳提取工艺条件：浸泡时间55min、微波时间4min、微波功率800W、微波温度90℃、料液比1:14(g/mL),水溶性膳食纤维提取率达到6.0%,NSP 含量为94.68%,SDF 综合评分为65.12%。     

Peanuts,Peanut Oil,and Fat Free Peanut Flour Reduced Cardiovascular Disease Risk Factors and the Development of Atherosclerosis in Syrian Golden Hamsters

ABSTRACT: Human clinical trials have demonstrated the cardiovascular protective properties of peanuts and peanut oil in decreasing total and low density lipoprotein cholesterol (LDL-C) without reducing high density lipoprotein cholesterol (HDL-C). The cardiovascular effects of the nonlipid portion of peanuts has not been evaluated even though that fraction contains arginine, flavonoids, folates, and other compounds that have been linked to cardiovascular health. The objective of this study was to evaluate the effects of fat free peanut flour (FFPF), peanuts, and peanut oil on cardiovascular disease (CVD) risk factors and the development of atherosclerosis in male Syrian golden hamsters. Each experimental diet group was fed a high fat, high cholesterol diet with various peanut components (FFPF, peanut oil, or peanuts) substituted for similar metabolic components in the control diet. Tissues were collected at week 0, 12, 18, and 24. Total plasma cholesterol (TPC), LDL-C, and HDL-C distributions were determined by high-performance gel filtration chromatography, while aortic total cholesterol (TC) and cholesteryl ester (CE) were determined by gas liquid chromatography. Peanuts, peanut oil, and FFPF diet groups had significantly (P < 0.05) lower TPC, non-HDL-C than the control group beginning at about 12 wk and continuing through the 24-wk study. HDL-C was not significantly different among the diet groups. Peanut and peanut component diets retarded an increase in TC and CE. Because CE is an indicator of the development of atherosclerosis this study demonstrated that peanuts, peanut oil, and FFPF retarded the development of atherosclerosis in animals consuming an atherosclerosis inducing diet.     

Effect of storage on chemical and sensory profiles of peanut pastes prepared with high‐oleic and normal peanuts

BACKGROUND: Peanut paste and peanut butter have high oil contents and are thus susceptible to developing rancidity and off‐flavours through lipid oxidation. Preservation of the chemical and sensory quality of these products is one of the main problems in the peanut industry. The purpose of this study was to compare the chemical and sensory stability of peanut paste prepared with high‐oleic peanuts (cv. Granoleico, GO‐P) with that of peanut paste prepared with normal peanuts (cv. Tegua, T‐P) from Argentina. RESULTS: Chemical (peroxide and p‐anisidine values and conjugated dienes) and sensory (roasted peanutty, oxidised and cardboard flavours) indicators of lipid oxidation were measured in peanut pastes stored at 4, 23 and 40 °C. Chemical indicator values and oxidised and cardboard flavours showed lower increments in GO‐P than in T‐P during storage. T‐P had significantly higher peroxide value than GO‐P. Roasted peanutty flavour showed a lower decrease in GO‐P. Peanut paste prepared with high‐oleic peanuts had four (at 4 °C), two (at 23 °C) and three (at 40 °C) times longer shelf‐life than peanut paste prepared with normal peanuts. CONCLUSION: These results indicate that high‐oleic Granoleico kernels provide peanut paste with higher protection against lipid oxidation. Copyright © 2010 Society of Chemical Industry     

Effect of gamma irradiation on the physico‐chemical and sensory properties of raw shelled peanuts (Arachis hypogaea L.) and pistachio nuts (Pistacia vera L.)

Backround The present study evaluated the quality of raw peanuts and pistachio nuts as a function of irradiation dose in order to determine dose levels causing minimal undesirable changes to these products. Physico‐chemical (colour, peroxide value, hexanal content, fatty acid composition, volatile compounds) and sensory (colour, texture, odour, taste) properties of raw peanuts and pistachio nuts were determined after irradiation at doses up to 7 kGy. Results Results showed an eight‐ and seven‐fold increase in peroxide value and a twelve and five‐fold increase in hexanal content after irradiation at a dose of 7 kGy for peanuts and pistachio nuts, respectively. An increase was also observed in saturated fatty acids (20.51–28.28% and 15.24–24.87%) with a parallel decrease in unsaturated fatty acids (79.49–71.72% and 84.76–75.13%) for peanuts and pistachio nuts, respectively. Likewise, volatile compounds such as aldehydes, alkanes, ketones and alcohols comprising secondary oxidation products of peanut and pistachio nut lipids increased after irradiation. Pistachio nut colour parameter a* and to a lesser extent parameters, L* and b* decreased after irradiation leading to a slight but noticeable darkening in product colour while colour parameter L*, b* and a* of raw peanut remained unchanged by irradiation up to 7 kGy. Conclusion Based on sensory evaluation, peanuts and pistachio nuts become unacceptable for consumption when irradiated at doses higher than 3 kGy. Copyright © 2009 Society of Chemical Industry