基于PLC的山核桃破壳自动化生产线控制系统研究

目的:解决目前山核桃破壳自动化生产线控制系统自动化水平低、效率低等问题.方法:在现有山核桃破壳自动生产线的基础上,提出一种基于PLC控制技术的山核桃破壳自动化生产线控制系统.以PLC为核心完成整个山核桃破壳自动化生产线的控制,包括破壳机、风选机、破壳分离机、色选机等设备.以直径18～22mm核桃为试验对象,对样机进行了验证.结果:相比于控制系统投入前,实施控制系统后提高了山核桃破壳率和降低了核仁损伤率,直径为18～22 mm的山核桃,破壳率100%,核仁损伤率5.02%,符合生产要求.结论:基于PLC的控制技术符合核桃全自动生产线的要求.     

小袋山核桃仁包装机袋膜纠偏模糊控制系统设计

为减小小袋山核桃仁包装机袋膜跑偏对产品外观与质量造成的影响,提出基于模糊控制的智能纠偏控制方案。在分析拉膜机构工作过程中袋膜跑偏原因与纠偏可行性的基础上,设计了纠偏控制模型,通过CCD传感器检测袋膜偏移量,建立模糊控制规则,实时调控拉膜速度与纠偏辊偏移角度,控制袋膜偏移量始终在要求范围内。利用改进DF-50B2型粉料自动包装机作为试验平台进行纠偏试验,并通过LabVIEW软件对纠偏模糊控制系统输出效果进行测试。试验结果表明,该控制系统具有较好的纠偏效果,拉膜速度为80mm/s时的纠偏精度最高达0.52mm,包装重量对纠偏效果没有较明显影响,但拉膜速度越大时袋膜偏移量也越大。该控制系统在保证产品质量前提下,加快了包装速度,进而提高了包装机工作效率。     

Pecan (Carya illinoinensis) oil consumer hedonic rating,sensory characteristic,satiating and energizing effect,and drivers of overall acceptance

With increasing global health and wellness product needs, pecan oil is getting popular in recent years. Although considered a gourmet oil because of its unique sensory and nutritional values, there is no publication focusing on consumer attitude toward pecan oil. This study, for the first time, investigated consumer acceptance, sensory quality, and emotional response to five pecan oils from native and improved varieties, with a comparison to an olive oil. All five pecan oils had positive hedonic ratings (>5, with a 9-point hedonic scale) for overall acceptance and the acceptance of oil flavor, raw-nut flavor, and thickness, while the olive oil was rated slightly lower than 5 for these attributes. Pecan oils had higher intensities in raw-nut flavor, but lower in overall oil flavor, fatty flavor, astringency, and thickness compared to olive oil. Off-flavor was not perceived in pecan oils, whereas it was perceived in olive oil. The six oils did not show significant differences in satiating effects; however, olive oil was rated lower in energizing effects than pecan oils, which showed a significant variety difference (p ≤ 0.05). Consumer overall acceptance was significantly, positively driven by energizing effects, followed by the acceptability of raw-nut flavor, thickness, and oil flavor; off-flavors were negative drivers. Results obtained from this study add direct pecan oil consumer insight: an asset for pecan growers, pecan processing industry, and pecan oil marketers.     

Quantitative extraction of pecan oil from small samples with supercritical carbon dioxide

A procedure to determine total oil content of pecan was developed for samples weighing 500 and 10 mg by supercritical fluid extraction (SFE) with carbon dioxide as the extraction solvent, and chilled hexane as the trapping solvent. Fatty acid methyl esters (FAMEs) were prepared from the total lipid fraction by using either an aliquot (500 mg starting weight) or the entire extract (10 mg starting weight). Total oil content obtained for either sample size with SFE was similar to that obtained with an organic solvent extraction technique. The fatty acid composition for the total lipid fraction of oils extracted with SFE was the same as for oils extracted with organic solvents, and oil composition did not change during SFE. Both oil yield and fatty acid composition were similar to those reported previously for pecan. Samples could be extracted and placed into FAME-derivatizing reagents in one day, and fatty acid composition of the total lipid fraction could be determined by gas-liquid chromatography the next day. The procedure, as demonstrated for pecan, should be suitable for other oilseeds, especially those containing low amounts of water.     

Efficacy of Antimicrobials Extracted from Organic Pecan Shell for Inhibiting the Growth of Listeria spp.

Growers and processors of USDA certified organic foods are in need of suitable organic antimicrobials. The purpose of the research reported here was to develop and test natural antimicrobials derived from an all‐natural by‐product, organic pecan shells. Unroasted and roasted organic pecan shells were subjected to solvent free extraction to produce antimicrobials that were tested against Listeria spp. and L. monocytogenes serotypes to determine the minimum inhibitory concentrations (MIC) of antimicrobials. The effectiveness of pecan shell extracts were further tested using a poultry skin model system and the growth inhibition of the Listeria cells adhered onto the skin model were quantified. The solvent free extracts of pecan shells inhibited Listeria strains at MICs as low as 0.38%. The antimicrobial effectiveness tests on a poultry skin model exhibited nearly a 2 log reduction of the inoculated cocktail mix of Listeria strains when extracts of pecan shell powder were used. The extracts also produced greater than a 4 log reduction of the indigenous spoilage bacteria on the chicken skin. Thus, the pecan shell extracts may prove to be very effective alternative antimicrobials against food pathogens and supplement the demand for effective natural antimicrobials for use in organic meat processing.     

山核桃饼粕分离蛋白的提取工艺研究

以山核桃饼粕为原料,利用碱溶酸沉的提取工艺,以碱提pH、料液比和碱提温度为实验因素,山核桃蛋白浸出率为目标建立回归数学模型,采用二次正交旋转组合设计实验方法得到山核桃蛋白的最优提取条件。实验结果表明:山核桃蛋白的最佳提取工艺为pH9.0、料液比1:25、碱提温度为57℃,在此条件下山核桃蛋白提取率可达到56.88%。     

自发气调储藏对薄壳山核桃坚果生理及品质的影响

本文分别以30 μm黄色聚氯乙烯保鲜袋、30 μm白色聚乙烯保鲜袋和50 μm白色聚乙烯保鲜袋为包装材料,研究了室温和4℃条件贮藏期间薄壳山核桃坚果的生理及营养品质变化。研究结果表明,与对照相比,气调保鲜包装（MAP）能使包装环境内形成低O2高、CO2环境,有利于保持薄壳山核桃中的总脂肪、不饱和脂肪酸和γ-生育酚的含量,延缓其呼吸速率、酸价、过氧化值和皂化值的上升。在供试的3种气调保鲜包装中,以50 μm白色聚乙烯保鲜袋的效果最好。     

薄壳山核桃主要生物活性成分及其作用研究进展

为了更好地推动薄壳山核桃生物活性成分的相关研究,对薄壳山核桃不饱和脂肪酸、酚类化合物、维生素E、植物甾醇、角鲨烯、类胡萝卜素等主要生物活性成分研究进展进行了综述,并总结了薄壳山核桃及其提取物在抗氧化、降血脂、降血糖、保护肝脏、抗癌等方面的保健作用。薄壳山核桃含有丰富的生物活性成分,基于其生物活性成分的新产品开发将是未来研究的重点。