Fast determination of royal jelly freshness by a chromogenic reaction

Royal jelly is one of the most important products of honeybees. Given its role in development of bee brood into fertile individuals of the royal caste it is also used in health products for human consumption. Royal jelly spoils and loses its health-promoting properties depending on storage duration and conditions. To ensure product quality before selling, it is therefore necessary to assess royal jelly freshness. Many indexes of freshness have been suggested, but they all lack reliability or require complex and time-consuming analyses. Here we describe a method to detect royal jelly freshness based on a chromogenic reaction between royal jelly and HCl. We demonstrate that analyses based on color parameters allow for the discrimination of royal jelly samples based on the duration of their storage. Color parameters of royal jelly stored at -18 and 4 °C for 28 d remained comparable to that of fresh samples, which supports the reliability of the method. The method of freshness determination described is practical, cheap, and fast and can thus be used in real-time when trading royal jelly. PRACTICAL APPLICATION: The method developed can be used to assess royal jelly freshness. It is practical, cheap, and fast and can thus be used in real-time when trading royal jelly.     

微波加热钝化黑米糠过氧化物酶

采用微波加热法,以过氧化物酶残余活力为指标,通过单因素和正交实验得出微波钝化黑米糠过氧化物酶的最佳条件为:黑米糠含水量26%、加热时间105s、加热功率900W,该优化条件下过氧化物酶残余活力为0.5%。旨在为黑米糠工业化开发提供基础科学依据。      

便捷式智能化大米新鲜度检测系统设计与应用

目的:实现大米新鲜度的快速无损检测。方法:研制一套基于纳米色敏传感器结合近红外光谱分析原理的便携式装置系统。对所采集到的不同掺陈度大米样品所对应色敏传感器的光谱数据,进行多梯度掺陈大米的鉴别与跨批次大米新鲜度的预测。结果:使用Si-CARS-PLS提取光谱特征变量,经LDA算法建模后判别模型的识别率最高,训练集和预测集的识别率分别为97.22%和95.83%。同时,PLSR模型预测跨批次数据具有更强的稳定性,不同批次大米样品数据训练集和预测集的相关系数(R_c、R_p)均稳定在0.95左右,均方根误差(RMSEC、RMSEP)均低于0.2,相对分析误差(RPD)均大于3。结论:该系统具有准确率高、便捷和预测模型鲁棒性好等特点,在大米新鲜度的现场检测中有很好的应用前景。     

冰温贮藏对西兰花保鲜的影响

研究冰温贮藏对西兰花保鲜效果的影响。将西兰花分为两组,一组存于冰温库中（-0.7～-0.4）℃,另一组存于普通冷库中（-1～1）℃。每14d取样测定其理化指标及营养成分。实验结果表明:冰温贮藏对于延缓西兰花可溶性固形物含量、可溶性糖浓度和VC含量的下降具有明显的效果,可显著抑制西兰花贮藏期间乙烯生成率,延迟乙烯高峰的出现,但对呼吸的抑制效果不大;冰温贮藏提高了西兰花POD、SOD和CAT等的活性,降低了PPO的活性,延缓了西兰花的衰老。这说明西兰花适于冰温贮藏,且冰温贮藏的效果优于普通冷藏的效果。      

肉品新鲜度智能指示标签的形成分类与机制研究进展

生鲜肉品在流通环境中易受到微生物、酶以及物理、化学等作用使其腐败变质,而消费者只能根据包装日期和有效期来判定肉品的新鲜度及安全性,对肉品在贮藏运输过程中所发生的质量变化,不能准确判定。智能指示标签技术恰恰能够更加清晰直观地实时监测肉品的新鲜程度。本文正是在智能指示标签概述的基础上,以肉品智能指示标签的分类形式为切入点,阐述不同类型指示标签的工作原理、应用优势以及新鲜度信息的表达形式,并从pH响应机制、硫化氢敏感机制、生物胺传感机制、酸性气体敏感机制以及微生物生态感应机制等方面深入论述智能指示标签在表征肉品新鲜程度上的内在机制,以期为提升现代智能包装以及基于肉品智能指示标签的研究与创新提供理论参考。     

稻谷新陈度检测技术研究进展

作为我国主粮之一,稻谷在收购过程中常出现陈粮二次兜售、染色米、漂白米、翻新米等问题。为控制稻谷品质、促进粮储安全、保障消费者健康,准确快速检测稻谷新陈度极其重要。本文综述了稻谷新陈度检测方法的最新研究进展。根据检测原理的不同,检测方法可分为感官检验法、化学检验法、物理检验法和其他检验法等。同时,本文介绍了检测方法的现状、优缺点及改进方法等。最后,本文讨论了稻谷新陈度检测方法的未来发展方向。本文希望能为消费者、粮食检验人员提供检测依据和借鉴,为粮食安全储藏和消费者“舌尖安全”保驾护航。     

超声波处理对黑米酒中酚类物质、颜色及抗氧化性的影响

研究了超声处理对黑米酒中酚类物质、颜色及羟基自由基清除能力的影响。结果显示:超声波处理后黑米酒中总酚含量、总黄酮含量、总花青素含量及清除自由基能力均有不同程度下降,而黑米酒亮度(L*)、红色(a*)及黄色(b*)的颜色特性均有一定程度增加;不同超声条件处理后,黑米酒中总花青素含量与其a*有明显相关性,表明总花青素是黑米酒呈现红色的主体物质;超声处理后黑米酒清除羟自由基的能力与黄酮、花青素等的变化呈明显相关性。上述部分指标的变化与自然熟化过程变化基本一致,表明超声在一定程度上可以起到辅助黑米酒熟化的作用。     

全脂米糠过氧化物酶挤压钝化参数研究

利用挤压稳定化方法处理全脂米糠,探索挤压加工参数对灭酶效果的影响规律。以挤压机机筒温度、物料含水率、螺杆转速、模孔直径为考察因素,过氧化物酶残余酶活力为评价指标,在单因素试验基础上进行响应面研究,试验结果表明,挤压工艺的因素排序为机筒温度物料含水率螺杆转速模孔直径,在机筒温度135℃,物料含水率22.5%,螺杆转速130 r/min,模孔直径8 mm的挤压条件下,过氧化物酶残余酶活达到最小值0.53%,钝化效果较好,过氧化物酶残余酶活低于微波法,稳定化程度较高。SEM电镜结果显示,挤压处理使米糠的微观结构发生复杂变化,更加易于人体的消化吸收。     

不同贮藏温度对青皮核桃保鲜的影响

以青皮核桃为试材,将果实分别贮藏在（5±1）、（0±0.5）、（-1±0.5）℃条件下,研究不同贮藏温度对青皮核桃保鲜效果的影响。结果表明,（-1±0.5）℃贮藏对青皮核桃含水量的下降、a*的升高、酸价的升高有延缓作用,可降低青皮核桃外果皮的呼吸强度,但对MDA含量的抑制作用不大,并有效提高了青皮核桃POD的活性,降低了PPO的活性,延缓了青皮核桃的衰老。与对照组的贮藏期相比,实验组一与实验组二分别延长了30d和45d。不同贮藏温度对青皮核桃保鲜效果顺序为:（-1±0.5）℃>（0±0.5）℃>（5±1）℃。这说明贮藏青皮核桃的适宜温度为（-1±0.5）℃。      

鱼类贮藏期间鲜度指标K值变化及鲜度评价

目的 研究鱼类肌肉在不同贮藏条件下的鲜度指标K值及鲜度变化情况。方法 鱼类肌肉在不同条件下贮藏, 肌肉中的ATP关联物用高氯酸溶液提取后用高效液相色谱进行检测, 通过公式计算出K值。结果 K值与鱼类的新鲜度变化趋势有较好的规律性, 随着贮藏时间延长K值增大, 温度越低变化越缓慢。在28~30 ℃条件下只能贮藏数小时, 4~5 ℃条件下可延长至5 d, ?2~0 ℃条件下贮藏大于15 d。结论 K值客观地反映了鱼类贮藏过程中的鲜度变化情况, 适合于作为鲜度的判定指标。     

Effects of storage conditions and cooking on colour and antioxidant activities of organic pigmented rice

Influences of the conditions of raw rice storage and cooking on parameters related to colour and antioxidant activities of organic hulled red fragrant rice were investigated. Raw rice samples were vacuum‐packed in oriented polypropylene/aluminium/linear low‐density polyethylene or nylon/linear low‐density polyethylene pouches and stored at ambient temperature or 15 °C up to 12 months. Cooked samples were prepared from aged raw samples. Kernel colour, total anthocyanin content (TAC) of acidic methanolic extracts as well as total phenolic content (TPC), reducing power (RP) and radical scavenging activity (RSA) of methanolic extracts and enzymatically digested samples were maintained during 12‐month storage, regardless of packaging materials and storage temperatures. Cooked kernels had larger L value, lower a and b values, and greater TAC (dry basis), comparing with the raw rice. Cooking caused drastic decrease in TPC, RP and RSA of methanolic extracts. Nevertheless, less negative impacts of cooking were found for enzymatically digested samples.     

列车贮藏方式对生猪肉原料新鲜度的影响研究

探究夏季高温期某铁路局集团公司旅客列车贮藏条件下生猪肉原料的品质变化,为改善餐车生猪肉保存及取用方式、保障旅客列车食品安全提供可靠依据。在实验室条件下模拟该列车餐车实际条件下生猪肉贮藏及取用方式:将生猪肉分别在4℃(冷藏)和-10℃(冷冻)两种条件下贮藏,再解冻,使用,再贮藏。通过猪肉的色泽、气味、组织状态感官指标以及挥发性盐基氮(TVB-N)、硫化氢、球蛋白沉淀理化指标的变化为依据,来评价猪肉的新鲜度。结果表明:夏季高温期间,该铁路局集团公司列车生猪肉原料,在4℃冷藏贮存条件下,有2d保质期,在-10℃冷冻贮藏条件下,10d内猪肉品质能够保持新鲜,满足铁路运输的时限要求。该铁路公司列车贮藏和使用生猪肉符合规范,用肉时限在保质期范围内,能够保证全年时段肉质新鲜安全。为保障铁路旅客的食品安全,生猪肉原料应贮存在制冷效果良好的冷冻冰箱内,取用肉类置于冷藏保存的,应在2d内使用完毕。     

基于可见/近红外高光谱成像技术的鸡蛋新鲜度无损检测

以400~1 000nm高光谱系统获得鸡蛋样本的高光谱图像,利用蒙特卡洛法检测异常样本,采用不同预处理方法处理原始光谱;应用竞争性正自适应加权算法(Competitive Adaptive Reweighted Sampling,CARS)、遗传偏最小二乘法(Genetic Algorithms PLS,GAPLS)和间隔蛙跳法(Interval Random Frog,IRF)对预处理后光谱数据提取特征波长;分别建立基于全光谱和特征波长的偏最小二乘回归(Partial Least Squares Regression,PLSR)和最小二乘支持向量机(Least Squares Support Vector Machine,LS-SVM)鸡蛋新鲜度预测模型。结果表明:标准正态变量变换(Standardized Normal Variate,SNV)法为最优预处理方法;利用CARS、GAPLS和IRF分别选出8,35,74个特征波长;基于GAPLS提取的特征波长的LS-SVM模型最优,其校正相关系数(Rc)为0.899,预测相关系数(Rp)为0.832。表明基于高光谱成像技术的鸡蛋新鲜度无损检测是可行的。     

Variations of colour,polyphenol oxidase and peroxidase activities during the production of low temperature dried pasta in various durum wheat genotypes

This research was conducted to determine the effect of milling and pasta making on yellow pigment content, soluble brown pigment content, polyphenol oxidase (PPO) activity and peroxidase (POD) activity in semolina and pasta derived from ten durum genotypes. Results showed that pasta colour was impacted more by the milling than by pasta making. The loss of yellow pigment content, POD activity, PPO activity and soluble brown pigment content due to milling was 1.3×, 4.4×, 6.2× and 17.5×, respectively, greater than losses due to pasta making. Dry pasta contained 62%, 31%, 16% and 25% of the original yellow pigment content, brown pigment content and PPO activity and POD activity in the grain, respectively. Semolina yellow pigment content had a positive effect on pasta colour while semolina protein content, ash content and speck count had negative effects. These results indicate the importance of selecting genotypes that have high yellow pigment content and excellent milling qualities.     

Nitro‐blue tetrazolium staining of starch‐synthesizing enzymes in developing rice grains

An in situ nitro‐blue tetrazolium (NBT) staining method was used to locate the activities of enzymes involved in starch synthesis in developing grains of field grown rice (Oryza sativa L.) cultivar Tainung 67 and its early ripening mutant SA 419. The results indicated that all the tested enzymes, including sucrose synthase, invertase, hexokinase, ADP‐glucose pyrophosphorylase, UDP‐glucose pyrophosphorylase and starch synthase, were detectable in developing rice endosperms by using NBT staining. The activity of these enzymes was also measurable by using chemical assays. The expression of enzyme activity, as indicated by the formation of blue formazan precipitate, in growing grain of Tainung 67 were visualized in entire endosperm at 11 days after anthesis (DAA). However, NBT staining shifted from central to peripheral region of endosperm after 18 DAA, and the staining disappeared at 25 DAA. Similar staining patterns were also observed in the growing grains of mutant SA 419, but the shift of staining from central to peripheral endosperm occurred at 11 DAA. Electron microscopy examinations showed that the growing patterns of starch granules, sampled from central and peripheral regions of endosperm, varied between two cultivars, with SA 419 growing faster than Tainung 67. Both cultivars showed that the shifts of NBT staining pattern coincided with the changes in the growing pattern of starch granules located in central and peripheral regions of endosperms. The NBT staining results showed that the activities of sucrose to starch conversion enzymes in mutant SA 419 declined and disappeared earlier than its wild‐type Tainung 67 and therefore it ripened earlier than cultivar Tainung 67. Copyright © 2005 Society of Chemical Industry     

米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响

以新鲜米糠为原料贮藏0、1、3、5、10 d得到不同酸败程度的米糠,稳定化和脱脂后制备米糠可溶性膳食纤维,研究米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响。结果表明:随着新鲜米糠贮藏时间的延长,米糠可溶性膳食纤维的还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH、O_2~-·能力均先上升后下降;米糠可溶性膳食纤维还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH在新鲜米糠贮藏5 d时达到最大值,分别为0.943(OD_(700))、35.16%、32.28%、73.51%和13.83%,米糠可溶性膳食纤维清除O_2~-·能力在新鲜米糠贮藏1 d达到最大值,为60.58%。     

优质籼米安全储藏技术研究

通过比较分析自然低温仓房(16℃)、空调控温仓房(20℃和25℃)以及不作控温处理的对照仓房储藏大米度夏时主要质量指标和品质指标变化规律、害虫发生情况,探讨储备大米宜储性控制关键指标,研究大米储藏安全度夏的可行性。结果表明,温度16℃、湿度65%是优质籼米黄花粘储藏防虫保质的最优储藏条件。在20℃、25℃储藏条件下的大米需结合防虫技术才能安全度夏,自然温度储藏条件下的大米不能安全度夏;色泽气味和品尝评分值是黄花粘宜储性控制关键指标。     

Residual peroxidase activity as influenced by blanching,SO2 treatment and freezing of cauliflowers

The influence of blanching time and SO₂ treatment on the residual peroxidase activity and its implication for the sensory quality of frozen cauliflowers were assessed after storage for up to one year at ?18°C. The treated cauliflowers, sealed in polythene bags, were placed in waxed paperboard cartons and frozen in a contact plate freezer at ?35°C. The sensory quality of frozen stored cauliflowers related well to their residual peroxidase activity, which was sensitive to the SO₂ treatment. Blanched cauliflowers following a brief dip in a metabisulphite solution prior to freezing gave a significantly (P<0.05) superior product even when stored for one year. The residual peroxidase activity, which ranged from 1 to 5.5% in the blanched samples, was below 1 % in the SO ₂-treated samples, and the SO₂ content of50 ppm found in these stored samples disappeared after 3 min cooking in boiling water.     

Nondestructive determination of salmon fillet freshness during storage at different temperatures by electronic nose system combined with radial basis function neural networks

This study develops a predictive model for determining freshness of salmon fillets during cold storage at different temperatures using electronic nose combined with principal component analysis (PCA) and radial basis function neural networks (RBFNNs). The electronic nose sensed ammonia/amines, hydrocarbons, solvents and aromatics that increased during storage. The concentrations of the volatiles were compared with the increased thiobarbituric acid (TBA), total volatile basic nitrogen (TVB-N), total aerobic bacteria count (TAC) and decreased of sensory assessments (SA). Gas chromatograph–ion mobility spectrometry analysis confirmed the changes in gas species. RBFNNs and PCA were used to establish predictive models and the relative errors of TBA, TVB-N and TAC by the PCA-RBFNNs model were all within ±10% and SA was within ±15%. These results suggest that the PCA-RBFNNs model can be used to predict changes in the freshness of salmon fillets stored at −2 to 10 °C.     

Recycling coffee grounds and tea leaf wastes to improve the yield and mineral content of grains of paddy rice

BACKGROUND: Coffee grounds and tea leaf wastes exhibit strong affinity for metals such as Fe and Zn. The objective of this experiment was to evaluate the effect of top‐dressing application of Fe‐ and Zn‐enriched coffee grounds and tea leaf wastes at the panicle initiation stage on the mineral content of rice grains and the yield of paddy rice. RESULTS: The Fe and Zn contents of brown rice grains increased significantly on application of both coffee and tea waste materials. The concentration of Mn was increased by top‐dressing application of coffee waste material only. For Cu, no significant (P < 0.05) differences were found between the control and ferrous sulfate/zinc sulfate treatment. The application of coffee and tea waste materials led to a significant (P < 0.05) increase in the number of grains per panicle, which was reflected in increases in the total number of grains per hill and in grain yield. CONCLUSION: The top‐dressing application of these materials is an excellent method to recycle coffee grounds and tea wastes from coffee shops. Use of these novel materials would not only reduce the waste going to landfill but would also benefit the mineral nutrition of rice consumers at low cost by increasing Fe and Zn levels of rice grains as well as grain yield. Copyright © 2011 Society of Chemical Industry