开心果采后射频杀虫技术及综合利用研究

发布时间：2018-06-04 01:34

  本文选题：采后开心果 + 射频　； 参考：《西北农林科技大学》2016年博士论文

【摘要】：开心果(Pistacia vera L.)与核桃、巴旦杏和榛子并称世界四大树坚果(tree nut)。其果仁富含油脂、蛋白质、矿物质、维生素与植物化学成分,具有很好的保健功效与药理作用。近年来,我国开心果消费量逐年增加,市场价格居高不下,属特种珍贵坚果。然而,采后虫害侵染造成的储藏品质损失与精深加工不足形成的产品低端单一问题,已严重阻碍我国坚果产业的发展。如何控制采后开心果虫害,保证储藏品质,提高精深加工水平,丰富产品种类,是我国坚果加工业发展中亟待研究与解决的问题。本课题以国内外开心果主要消费品种科曼为研究对象,利用射频加热技术进行采后开心果仓储害虫的杀灭研究,并在此基础上对射频杀虫处理后的开心果样品进行综合加工利用研究。具体研究内容为:(1)利用终端开路同轴探头技术,测量了不同含水量与含盐量开心果仁的介电特性,计算特定频率下电磁波的穿透深度。(2)研究了开心果的射频杀虫单批次处理工艺,优化了射频加热的最佳极板间距、冷却方法与加热均匀性,明确了射频杀虫对开心果储藏稳定性的影响。(3)采用射频杀虫连续化处理方式,开展了射频加热均匀性、害虫死亡率、加热效率、处理量等工业放大研究。(4)用液压冷榨法获得未烘焙、传统烘焙、微波烘焙三种开心果油,针对上述开心果油进行了理化特性、香气成分与氧化稳定性研究。(5)以未烘焙与烘焙开心果仁经冷榨出油后的半脱脂粉为原料,用石油醚浸提获得全脱脂样品。测定并分析了半脱脂与全脱脂两种开心果粉的营养成分、功能特性、生物活性及微观结构。(6)用静态称重法测定了全脂、半脱脂、全脱脂三种开心果粉的解吸吸附平衡含水量,确定了最佳等温线模型,计算了样品的单层水含量与等量吸着热。主要结论如下:(1)开心果仁的介电特性随频率升高而减小,其中高含水量样品(15%)在低频(100 MHz)范围内,介电损耗的减小幅度更为显著。果仁损耗因子随含盐量增加而显著增大,但介电常数无显著改变。射频波段果仁损耗因子显著小于害虫,电磁波对开心果与害虫具有潜在的选择性加热效应。27 MHz射频杀虫时,开心果最大堆叠厚度可达24 cm,915 MHz微波杀虫时仅为4-6 cm,射频加热更适于进行大规模工业化杀虫处理。(2)利用27.12 MHz 6 kW中试规模射频加热系统对1.8 kg带壳与2.0 kg脱壳开心果进行杀虫单批次处理,分别仅需5.5和5.6 min即可使中心温度达到55°C。射频杀虫时,两种开心果辅以热风表面加热、往复运动、混合搅拌等措施可以改善加热均匀性。射频杀虫处理对开心果品质与储藏稳定性无显著影响。射频杀虫连续化处理中,射频加热的均匀性优于单批次杀虫处理的加热均匀性,可快速有效杀灭常见仓储害虫印度谷螟。当杀虫处理量为264.3 kg/h时,系统的平均加热效率为70%。(3)与未烘焙开心果仁冷榨油相比,适度烘焙处理,开心果油的过氧化值略有增加,叶绿素含量小幅降低,色泽相对变暗,总酚含量与抗氧化能力显著增强。未烘焙开心果冷榨油在结晶过程中的热相变峰值温度分别为-47.15和-19.85°C,融化过程中分别为-13.11和3.11°C,烘焙处理后油脂的热相变温度、融化和结晶曲线未发生明显变化。烘焙能促使开心果冷榨油中吡嗪类物质的形成,其中2-乙基-5-甲基吡嗪,3-乙基-2,5-二甲基吡嗪和3,5-二乙基-2-甲基吡嗪等化合物相对含量较高,对烘焙油样风味特征的形成发挥重要作用。开心果冷榨油对光氧化与自动氧化均有较强敏感性,采用不透光容器包装并添加0.01%(w/w)的特丁基对苯二酚(TBHQ)或0.02%的抗坏血酸棕榈酸酯(AP)或0.07%的迷迭香提取物(RME),在室温条件下储藏其良好品质可至少保持4个月。(4)全脱脂处理后,开心果粉的黄色与绿色值较全脂和半脱脂粉显著减小。烘焙与未烘焙开心果脱脂粉的宏量营养素含量无显著差异,但烘焙开心果脱脂粉的色泽整体偏暗、氨基酸含量有所降低。烘焙处理对开心果粉的功能特性无显著影响,但脱脂处理后其吸水/油力、乳化能力、乳化稳定性、起泡能力均显著高于全脂粉,其中全脱脂粉性能最高。烘焙开心果半脱脂粉的多酚和黄酮类含量最高,分别为792 mg GAE/100 g粉(d.b.)和280.30 mg RE/100 g粉(d.b.)。同时具有最强的抗氧化能力,DPPH·清除力和铁氰化钾还原力分别为78.12和130.51μmol Trolox/g粉(d.b.)。开心果脱脂粉中淀粉颗粒为表面光滑的椭圆球状,直径介于5-15μm。开心果半脱脂粉的蛋白质与淀粉颗粒集中分布于表面光滑的连续结构中,而在全脱脂粉中蛋白质与淀粉颗粒分散且表面呈多孔状。(5)按BET分类法,开心果全脂粉、半脱脂粉、全脱脂粉的解吸吸附等温线属第二类,曲线呈S形。根据IUPAC分类,三种开心果粉的解吸吸附滞后现象为H3型。相同温度与水活度下,全脱脂粉的解吸吸附平衡含水量最高、半脱脂粉次之、全脂粉最低。统计分析表明:Smith模型为全脂粉等温线数据的最佳模型,Halsey模型为半脱脂粉和全脱脂粉的最佳模型。15-35°C时开心果全脂、半脱脂、全脱脂粉的单分子层水含量分别为2.433-3.404,3.784-4.823和4.987-6.687 g/100 g(d.b.)。25°C平衡含水量2-40%(d.b.)范围内,开心果全脂、半脱脂、全脱脂粉的等量吸着热分别为74.67-44.76,99.44-44.75和133.28-44.80 kJ/mol。其中,在低含水量范围内,均表现为等量解吸热大于吸附热。
[Abstract]:Pistacia Vera L. and walnut, apricot and hazelnut and the world's four big tree nuts (tree nut). Their nuts are rich in oil, protein, minerals, vitamins and phytochemicals, and have good health and pharmacological effects. In recent years, the consumption of pistachios in China has increased year by year, and the market price is high, which is a special and precious firm. However, it has seriously hindered the development of the nut industry in China. How to control the Postharvest pistachio, guarantee the quality of the storage, improve the quality of the intensive processing, and enrich the product types, is an urgent problem in the development of the nut processing industry in China. In order to solve the problem, the subject takes kcoman, the main product of domestic and foreign pistachios, as the research object, and uses the radio frequency heating technology to study the killing of the storage pests in the Postharvest pistachios. On this basis, the synthetic processing and utilization of the pistachio samples after the radiofrequency insecticidal treatment are studied. The specific contents are as follows: (1) using the terminal opening coaxial The probe technique was used to measure the dielectric properties of different water content and salt content, and to calculate the penetration depth of the electromagnetic wave at a specific frequency. (2) a single batch process of radio frequency killing of pistachios was studied. The optimum spacing of the plate, the cooling method and the heating uniformity were optimized, and the storage stability of the radiofrequency insecticide to the pistachios was clear. (3) using radio frequency insecticidal continuous treatment, radio frequency heating uniformity, pest mortality, heating efficiency, processing quantity and other industrial enlargement studies. (4) three kinds of pistachio oil were obtained by hydraulic cold pressing, three kinds of pistachios oil were baked, traditional baking and microwave roasting, and the physicochemical properties, aroma components and oxidation of the above pistachio oil were carried out. The study of stability. (5) the total degreasing samples were obtained from the semi skimmed powder of the baked and baked happy nuts after the cold extraction of oil, and the total degreasing samples were extracted with petroleum ether. The nutritional components, functional properties, biological activity and microscopic structure of two kinds of happy fruit powder, semi degreased and full degreased, were measured and analyzed. (6) the total fat, semi degreasing and whole fat were measured by static weighing method. The best isotherm model was determined by desorption and adsorption of the three kinds of skim fruit powder. The main conclusions were as follows: (1) the dielectric properties of the kernel were decreased with the increase of frequency, of which the high moisture content (15%) decreased in the range of low frequency (100 MHz), and the decrease of dielectric loss was more than that of the high water content. The loss factor of kernel loss significantly increased with the increase of salt content, but there was no significant change in dielectric constant. The kernel loss factor of the radio frequency band was significantly smaller than that of the pest. The electromagnetic wave has a potential selective heating effect on the pistachios and pests.27 MHz radiofrequency, the maximum stack thickness of the pistachios can reach 24 cm, and the 915 MHz microwave killing is only 4. -6 cm, RF heating is more suitable for large-scale industrial insecticidal treatment. (2) using a pilot scale radio frequency heating system of 27.12 MHz 6 kW, the 1.8 kg belt shell and 2 kg shell pistachios are treated with single batch. Only 5.5 and 5.6 min can make the center temperature reach 55 degree C., and two kinds of pistachios are heated on the hot air surface. The reciprocating movement, mixed mixing and other measures can improve the heating uniformity. Radio frequency insecticidal treatment has no significant effect on the quality of pistachios and storage stability. In the radiofrequency continuous treatment, the uniformity of the radiofrequency heating is better than the uniformity of the single batch of insecticidal treatment. It can quickly and effectively kill the India Valley borer, a common storage pest. The average heating efficiency of the system was 264.3 kg/h, and the average heating efficiency of the system was 70%. (3) compared with the cold pressed oil from the non baked happy nuts. The peroxide value of the pistachio oil increased slightly, the content of chlorophyll decreased slightly, the color and lustre darkened, the total phenol content and the antioxidant capacity increased significantly. The peak temperature of the thermal phase transition is -47.15 and -19.85 C respectively. The melting process is -13.11 and 3.11 degree C respectively. The thermal phase transition temperature of the oil after baking is not changed obviously. The baking can promote the formation of pyrazine in the cold squeezing oil of the pistachio, including 2- ethyl -5- methylpyrazine, 3- ethyl -2,5- two methylpyrazine and 3,5-. Two ethyl -2- methyl pyrazine and other compounds have a relatively high relative content and play an important role in the formation of the flavor characteristics of the baked oil. The cold pressed pistachio oil has a strong sensitivity to photooxidation and automatic oxidation. A 0.01% (w/w) of terbutylhydroquinone (TBHQ) or 0.02% ascorbate palmitate (AP) or 0.07 is added to the cold pressed container of the pistachio. The good quality of rosemary extract (RME) could be kept for at least 4 months at room temperature. (4) after full degreasing, the yellow and green value of happy fruit powder decreased significantly than that of full fat and semi degreased powder. There was no significant difference in the macro nutrient content of the baked and roasted pistachio powder, but the color and lustre of the baked pistachio skimmed powder was full. The bakery treatment had no significant effect on the functional properties of the happy fruit powder, but the water absorption / oil capacity, emulsifying ability, emulsifying stability, and foaming ability were significantly higher than that of the whole fat powder after the degreasing treatment, and the full dehydration powder was the highest. The content of polyphenols and flavonoids in the baked pistachio semi degreased powder was 7, respectively. 92 mg GAE/100 g powder (D.B.) and 280.30 mg RE/100 g powder (D.B.). At the same time it has the strongest antioxidant capacity. The DPPH clear force and potassium ferricyanide reduction force are 78.12 and 130.51 micron mol Trolox/g powder (D.B.). The starch granules in the pistachio skimmed powder are smooth and ellipsoidal, and the diameter of the protein with the diameter of 5-15 micron pistachio semi skimmed powder is in diameter. The starch granules were concentrated in the smooth surface of the continuous structure, while the protein and starch granules were dispersed in the full skimmed powder and the surface was porous. (5) according to the BET classification, the desorption isotherm of the pistachio full fat powder, the semi degreased powder and the total degreased powder was of the second class, the curve showed S shape. According to IUPAC classification, the desorption and adsorption hysteresis of three kinds of happy fruit powder After the same temperature and water activity, under the same temperature and water activity, the desorption adsorption equilibrium moisture content of the total degreasing powder is the highest, the half degreasing powder is the second and the whole fat powder is the lowest. The statistical analysis shows that the Smith model is the best model of the whole fat powder isotherm data, and the Halsey model is the best model of the semi degreased powder and the full degreasing powder for.15-35 [C], and the Halsey is semi degreased. The water content of the single molecular layer of full degreasing powder is 2.433-3.404,3.784-4.823 and 4.987-6.687 g/100 g (D.B.).25 / C equilibrium water content 2-40% (D.B.). The whole fat of pistachio, semi degreasing, and the equal amount of absorption heat of the total degrease powder are 74.67-44.76,99.44-44.75 and 133.28-44.80 kJ/mol., respectively. In the range of low water content, the same quantity is equal. The solution heat absorption is greater than the adsorption heat.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S436.64
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本文编号：1975226