电子束辐照对丹棱冻粑杀菌效果及保质期的影响

以白糖味丹棱冻粑为试材,采用1、2、3、4、5、6 kGy剂量电子束辐照后贮藏在3±1℃条件下,对贮藏期内丹棱冻粑大肠菌群、菌落总数、霉菌进行测定,结合感官评价分析不同剂量电子束辐照对丹棱冻粑杀菌效果及保质期的影响。结果表明:当辐照剂量为3 kGy时,丹棱冻粑的大肠菌群(CFU/g)由初始的"400/300/450/400/500"降低到"10/10/10/10/10";当辐照剂量为4 kGy时,丹棱冻粑的霉菌(CFU/g)由初始的"350"降低到"10";当辐照剂量为5 kGy时,丹棱冻粑的菌落总数(CFU/g)由初始的"6 000/7 000/9 000/5 000/6 000"降低到"10/10/10/10/10";3、4 kGy剂量辐照处理丹棱冻粑后贮藏在3±1℃条件下,保质期分别为15、24 d;丹棱冻粑在3±1℃贮藏前采取3-4 kGy电子束辐照处理较为合适。     

辐照改性对魔芋胶的影响

采用^60COγ-射线对魔芋粉进行辐照处理,辐照剂量分别为2、4、6、8和10kGy,然后对不同辐照剂量的魔芋样品测定其特性黏度、流变性等指标。结果表明：魔芋胶经6和8kGy辐照后其特性黏度和黏度值与对照相比均有所下降,而在10kGy辐照剂量时则粘均分子量和黏度值下降明显。辐照前后魔芋胶的流体特征不变,均为宾汉塑性流体,但经过10kGy辐照后其屈服应力值由8.63Pa降低到4.51Pa。辐照后魔芋胶的黏度热可逆性提高,经8kGy辐照的样品黏度热可逆性最好。     

电子束辐照对雪花酥杀菌效果及感官品质的影响

以烘焙连锁店自制自售的散装雪花酥为研究对象,研究电子束辐照对其杀菌效果及感官品质的影响。结果表明:随着辐照剂量的增加,大肠菌群、霉菌、细菌的存活率减少,感官品质下降;当辐照剂量为3kGy时,雪花酥的大肠菌群(CFU/g)由初始的"500/400/300/450/300"降低到"10/10/10/10/10"、霉菌(CFU/g)由初始的"170"降低到"10"、菌落总数(CFU/g)由初始的"6000/7000/6500/8000/10000"降低到"200/100/150/150/200";当辐照剂量为5kGy时,雪花酥的菌落总数(CFU/g)降低到"10/10/10/10/10";2kGy及以上的电子束辐照可将雪花酥的大肠菌群、霉菌、菌落总数控制在国家规定的限量标准范围内;辐照剂量为1～3kGy时雪花酥感官品质没有明显变化;综合考虑,雪花酥采用2～3kGy电子束辐照处理较为合适。     

辐照对峰甘板栗货架品质的影响

研究~(60)Co-γ射线辐照对真空包装峰甘板栗货架期指标的影响及其机制,初步确定延长货架期的最佳辐照剂量。通过~(60)Co-γ射线以0、0.5、1.0、3.0、3.5、4.0、4.5、5.0 kGy剂量辐照峰甘板栗,分别在贮存0、10、15、20、30 d时检测样品的微生物指标(菌落总数、霉菌及酵母数、大肠菌数、沙门氏菌数)、感官指标和理化指标。结果表明:辐照处理对峰甘板栗能够起到很好的杀菌作用;结合峰甘板栗感官品质评定及生理生化数据分析,辐照剂量为4.0 kGy时,可改善峰甘板栗感官质量并保持理化营养指标。初步认为,在4℃条件下,辐照剂量为4.0 kGy时,在微生物安全限量方面,使货架期延长至少20 d。     

不同剂量60Co-γ射线辐照对烟鸡胸肉贮藏过程中滋味的影响

目的 研究60Co-γ 辐照对烟鸡胸肉菌落总数、感官和滋味成分的影响,探讨其在烟鸡胸肉保鲜中的可行性。方法 采用食品中菌落总数测量烟鸡胸肉的菌落总数,全自动氨基酸分析仪测量游离氨基酸,高效液相法测量呈味核苷酸、有机酸,并结合感官评定法分析辐照处理对烟鸡胸肉滋味和质量的影响。结果 辐照能够有效杀菌并延长烟鸡胸肉的货架期,促进鲜味和甜味游离氨基酸的增加,减少苦味游离氨基酸。辐照处理后2~4 kGy的呈味核苷酸腺苷-5′-二磷酸(ADP)和腺苷-5′-一磷酸(AMP)减少,但肌苷-5′-一磷酸(IMP)无显著变化,6 kGy则显著增加IMP,辐照对烟鸡胸肉的鲜味具有提升作用。2~4 kGy辐照处理,丙酮酸含量有所减少。贮藏过程中,对照组和辐照组的感官评价均显著下降(P<0.05)。3和4 kGy的鲜味和甜味游离氨基酸含量维持较好,4和6 kGy的呈甜味和鲜味核苷酸下降最少,3和4 kGy的丙酮酸含量下降最少,2和6 kGy的苹果酸含量下降较少。结论 3和4 kGy剂量的60Co-γ 辐照对烟鸡胸肉滋味成分和感官评价没有明显的负面影响,并能有效延缓烟鸡胸肉的货架期。     

辐照蛋糕的杀菌保鲜效果及对蛋糕感官品质的影响

为了有效延长蛋糕的保质期,使用0、1、3、5、7、9kGy的60Coγ射线辐照蛋糕,分别在贮存0、30、60、90d时检测样品中的霉菌总数、菌落总数、大肠菌群、致病菌,并进行了感官评价试验。结果表明,随着辐照剂量的增加,微生物的存活率减小。蛋糕经1kGy剂量辐照,可杀死100%的霉菌和大肠菌群,菌落总数也降低至5.6%,常温下贮存90d后,蛋糕未产生任何霉变现象,且1~3kGy剂量辐照不会改变蛋糕的感官品质。因此60Coγ射线辐照是一种有效的延长蛋糕保质期的灭菌方法。     

电子束辐照对新疆干果品质的影响及其最高耐受剂量的确定

目的 探究电子束辐照对4种新疆干果品质的影响,确定干果辐照工艺的最高耐受剂量。方法 采用0、2、4、6、8和10 kGy不同剂量电子束处理枸杞干、红枣干、无花果干、小白杏干,研究不同辐照剂量对水分、维生素C、总酸、总糖4种理化指标及色度、外观、风味、色泽和口感等5种感官品质的影响。结果 仅8 kGy辐照处理对枸杞干口感指标有不良影响,其他3种干果的感官指标几乎不受辐照处理的影响; 10 kGy以内的辐照处理对红枣干的品质无不良影响;无花果干的总酸含量在辐照剂量>6kGy时有所上升,维生素C含量在10 kGy处理时显著低于对照;辐照剂量≥6 kGy时,小白杏干维生素C含量显著降低。结论 通过对电子束辐照新疆干果的品质影响及最高耐受辐照剂量的研究,确定枸杞干、红枣干、无花果干和小白杏干的最高耐受剂量分别是8、10、6和6 kGy。为电子束辐照在新疆干果灭菌工艺中的应用提供了理论基础。     

基于正交偏最小二乘判别分析探究60Co-γ辐照对羊肚菌采后低温贮藏品质的影响

目的：探究60Co-γ辐照处理对采后低温贮藏期间羊肚菌保鲜效果的影响。方法：以黑脉羊肚菌为试材,分别用实际吸收剂量1.64、2.18、2.43 kGy和2.93 kGy进行辐照处理,测定低温贮藏期间其感官品质和理化指标的变化。采用正交偏最小二乘判别分析（orthogonal partial least squares-discriminant analysis,OPLS-DA）建立基于羊肚菌理化品质指标的辐照处理判别模型,并采用变异权重参数值（variable importance in the projection,VIP）筛选差异显著指标。结果：经不同辐照剂量处理后,羊肚菌在4 ℃贮藏条件下其感官品质和理化特性呈现不同的变化规律。贮藏5 d后,与对照组相比,1.64 kGy和2.18 kGy辐照处理能提高过氧化氢酶活力、总酚含量和类黄酮含量,降低丙二醛含量、多酚氧化酶活力和过氧化物酶活力,有效延缓褐变和软化现象,其中1.64 kGy剂量处理保鲜效果最好（P＜0.05）,而2.43 kGy和2.93 kGy辐照处理样品则在贮藏末期品质劣变加剧。通过构建辐照处理判别模型,有效区分样品因辐照处理所造成的差异,并筛选出过氧化氢酶和过氧化物酶活力为相应的差异显著指标。结论：1.64 kGy和2.18 kGy辐照处理可明显延缓羊肚菌采后品质的劣变,且1.64 kGy处理组和对照组差异最大;OPLS-DA法能有效区分不同处理的样品组。     

不同剂量60Co γ辐照对蓝莓果实贮藏品质的影响

目的探索~(60)Coγ辐照处理对蓝莓果实保鲜效果的影响。方法采用不同的辐照剂量处理"蓝丰"蓝莓,以辐照的蓝莓为研究对象,研究其果实表面微生物的种类和数量、果实腐烂率和硬度、以及相关感官品质在冷藏期间的变化规律。结果辐照处理对蓝莓果实表面微生物有很好的杀灭和抑制作用,辐照剂量越高,效果越好,且微生物对辐照剂量的敏感程度依次为:细菌霉菌酵母菌。0.5 kGy的辐照处理对冷藏期间蓝莓果实保鲜效果不明显(P0.05),3.0 kGy的辐照处理能够加速冷藏后期蓝莓的腐烂变质,适当的辐照剂量(1.0~2.5 kGy)能够很好地降低腐烂率,保持果实硬度和保护果实感官品质,其中2.5 kGy辐照剂量对蓝莓果实的保鲜效果最佳,贮藏35 d后,果实腐烂率最低(3.35%),果实硬度最高(1.08 kg/cm~2)。结论辐照保鲜蓝莓的最低有效剂量为1.0 kGy,最高耐受剂量为2.5 kGy,本研究为蓝莓的辐照保鲜提供了应用基础和科学依据。     

电子束辐照对泥蚶杀菌保鲜效果的影响

目的：研究电子束辐照对泥蚶微生物数量及其感官质量的影响。方法：泥蚶经不同剂量电子束处理,测定辐照后及冷藏期间菌落总数、大肠菌群及其感官评分。结果：电子束辐照能有效地杀灭泥蚶中的微生物,经过0、1、3、5、7、9kGy 不同剂量处理,泥蚶的菌落总数逐步下降,当泥蚶的初始菌落总数为3.10 × 105CFU/g时, D10=3.12kGy;泥蚶的感官质量与辐照剂量有关,经过7、9kGy 剂量处理后样品产生令人不愉快的异味。结论：结合辐照后及冷藏期泥蚶的微生物和感官指标,泥蚶电子束冷杀菌的适宜剂量为3～5kGy,经3～5kGy 处理后,泥蚶的货架期由对照组的5d 延长至15～19d。     

Detection of 2,4,6-trichloroanisole in microorganism-free irradiated raisins by solid-phase microextraction and GC-MS

The occurrence of 2,4,6-trichloroanisole (TCA) in nonprocessed dry-on-the-vine (DOV) and Thompson seedless irradiated raisins extracted by solvent-free solid-phase microextraction (SPME) was confirmed using gas chromatography/mass spectrometry. The 42 kGy (kilo Gray) dose irradiated DOV and Thompson seedless raisins incubated in five growth media were shown to be free of microorganisms. The quantity of TCA in the irradiated raisins was 0.39±0.05 ng/kg compared with 0.56±0.17 ng/kg in nonirradiated samples. The observation supports the view that raisins biosynthesize a minute but detectable quantity of TCA. The SPME fiber (divinylbenzene/carboxen/polydimethylsiloxane) method was simpler and quicker than the Likens-Nickerson extraction method for TCA determination. The biochemical mechanism of TCA production in raisin grape is unknown, but information in the biochemical literature of abundant phenolic substrates in grape berry, the presence of methyltransferases in Vitis tissues and of a chlorinating system provides a plausible basis for further investigation of the process.     

响应面法优化超声波辅助清洗无核绿葡萄干工艺

针对葡萄干加工企业清洗无核绿葡萄干后无核绿葡萄干极易褐变的问题,采用超声波辅助清洗工艺,在单因素实验基础上,选择清洗剂酒精度、清洗温度和清洗时间为影响因子,褐变指数BI值为指标,通过响应曲面法设计和分析,最佳清洗条件下清洗的葡萄干用热泵干燥。实验表明无核绿葡萄干超声波辅助清洗工艺的最佳条件:清洗剂酒精度44%vol、清洗温度9 ℃、清洗时间90 s,在此条件下,无核绿葡萄干BI值仅为33.43,较传统自来水喷淋清洗降低26.98%。热泵干燥葡萄干的最佳温度是50 ℃,无核绿葡萄干BI值仅为23.69,略低于未清洗无核绿葡萄干,较相同温度下热风干燥降低28.52%。     

Effect of the gamma radiation dose rate on psychrotrophic bacteria, thiobarbituric acid reactive substances, and sensory characteristics of mechanically deboned chicken meat

Frozen samples of mechanically deboned chicken meat (MDCM) with skin were irradiated with gamma radiation doses of 0.0 kGy (control) and 3 kGy at 2 different radiation dose rates: 0.32 kGy/h (3 kGy) and 4.04 kGy/h (3 kGy). Batches of irradiated and control samples were evaluated during 11 d of refrigerated (2 ± 1 °C) storage for the following parameters: total psychrotrophic bacteria count, thiobarbituric acid reactive substances (TBARS), evaluation of objective color (L*, a*, and b*) and a sensory evaluation (irradiated odor, oxidized odor, pink and brown colors). No statistical difference (P > 0.05) was found amongst the TBARS values obtained for the MDCM samples irradiated with dose rates of 0.32 and 4.04 kGy/h. There was a significant increase (P < 0.05) in the psychrotrophic bacterial count as from the 7th day of refrigerated storage, for the MDCM samples irradiated at the dose rate of 4.04 kGy/h. With respect to the attribute of oxidized odor, the samples irradiated with a dose rate of 0.32 kGy/h showed a stronger intensity and were significantly different (P < 0.05) from the sample irradiated with a dose rate of 4.04 kGy/h on days 0 and 2 of refrigerated storage. Irradiation with a dose rate of 4.04 kGy/h (3 kGy) was shown to be the best condition for the processing of MDCM according to the evaluation of all the variables, under the conditions of this study. Practical Application: The results obtained for the application of different dose rates of ionizing radiation to mechanically deboned chicken meat will provide the food industry with information concerning the definition of the best processing conditions to maximize the sensory and food quality.     

Microbiological, nutritional and sensory evaluation of long-time stored amaranth biscuits produced from irradiation-treated amaranth grain

The paper presents some results achieved by the evaluation of microbiological (total bacterial count, coliform bacteria, aerobic sporeforming bacteria, yeasts and moulds), nutritional (lysine) and sensory (shape, surface, colour consistency, taste, odour, the profiling of tastiness) quality and of the aw values of amaranth-based biscuits produced from the amaranth grain irradiated by various ionizing radiation doses (1.5, 3 and 5 kGy, source 60Co) and stored for the period of 12 months at the laboratory temperature (20-25 degrees C). The irradiation dose providing the biscuits maximum hygienic, nutritional and sensory quality maintained up to the end of the one-year storage was 5 kGy.     

The effectiveness of electron beam irradiation to reduce or eliminate mould in cork stoppers

The objective of this research project was to reduce or eliminate moulds known to cause TCA using electron beam (e‐beam) irradiation. Four types of cork were inoculated with Paecilomyces viridis, Penicillium glabrum, Penicillium chrysogenum, Mucor racemosus, Trichoderma viride, Aspergillus oryzae and Cladosporium oxysporum. Cork samples were treated with 5, 10 or 15 kilograys (kGy) of e‐beam irradiation, respectively. Sensory evaluation revealed that irradiation had little or no effect on the overall quality of wine with irradiated corks stored for 56 months. Cork samples viewed under a scanning electron microscope (SEM) showed some structural changes compared to control corks. The results suggest that e‐beam irradiation can significantly reduce or eliminate the moulds known to cause TCA in cork.     

Effects of Low-dose Electron Beam Irradiation on Respiration, Microbiology, Texture, Color, and Sensory Characteristics of Fresh-cut Cantaloupe Stored in Modified-atmosphere Packages

Fresh‐cut cantaloupe was placed in modified‐atmosphere packages (4% oxygen, 10% carbon dioxide) and irradiated at 0 (control), 0.5, and 1.0 kGy. Irradiated samples had a lower and more stable rate of respiration than non‐irradiated samples over about 20 d. Total plate counts were higher (P < 0.05) in non‐irradiated control samples through day 11 (Trial 1) and for all dates tested (Trial 2). Color and texture remained stable for the duration of each study as measured by instruments and trained sensory panels. Sensory evaluation rated the 1.0‐kGy sample highest in “sweetness” and “cantaloupe flavor intensity” and lowest in “off‐flavor” after 17 (±3) d of storage. Low‐dose electron beam irradiation of fresh‐cut cantaloupe with modified‐atmosphere packaging offers promise as a method of extending shelf life.     

Microbial and sensory quality of marinated and irradiated chicken

Chicken legs were subjected to two pretreatments (packaged in air or marinated in natural plant extracts and then packaged in air) followed by irradiation (0, 3, or 5 kGy). The control and irradiated chicken legs were stored at 4 degrees C and underwent microbial analysis (mesophilic aerobic plate counts and Salmonella detection) and sensory evaluation at predetermined intervals. Microbial analysis indicated that irradiation had a significant effect (P < or = 0.05) on the mesophilic aerobic plate counts of the poultry. For each treatment, the bacterial growth decreased with an increase of irradiation dose. The marinade had an additive effect with irradiation in reducing bacterial growth and controlling proliferation during storage at 4 +/- 1 degree C. No Salmonella was observed until day 12 in marinated chicken irradiated at 3 kGy and for all experiments with chicken legs stored under air or marinated at 5 kGy. However, Salmonella was found in chicken legs irradiated at 3 kGy in air and in nonirradiated samples. The sensory evaluation indicated a significant (P < or = 0.05) difference in odor and flavor intensities between the irradiated chicken at 5 kGy and the control. No significant difference was found (P > 0.05) between the marinated chicken irradiated at 5 kGy and the control.     

RHEOLOGICAL PROPERTIES OF BEDS OF RAISINS

The rheological properties of beds of Sun-dried Sultana and Corinth raisins equilibrated to various moisture levels were investigated. Raisin beds of fixed bulk density at various configurations were compressed in a cylindrical test cell, and the apparent modulus and the two constants of an empirical model were estimated from the linearized stress/strain and relaxation curves. Beds of black Corinth raisins were more elastic than Sultana (seedless) raisins at moistures lower than 18%, but both types of raisins showed similar rheological behavior at higher moistures. The unrelaxed stress of all beds, after 10 min of relaxation, was about 25% of the initial stress. Beds of randomly mixed raisins of different moisture content appeared to be more elastic when the proportion of the moist raisins was increased. The apparent modulus of columns of raisins decreased as the number of raisins per column and the number of adjoining rows were increased.     

Influence of processing on the extension of shelf-life of Nagli-fish (Sillago sihama) by gamma radiation

Studies were carried out to evaluate the microbiological profile, shelf-life and quality of Nagli fish (Sillago sihama) subjected to gamma irradiation. Non-irradiated samples were unacceptable organoleptically after 7–8 days of storage at 1–2°C while irradiated samples (2 and 3 kGy) were acceptable up to 19 days. Dressing prior to irradiation had no additional advantage to shelf-life over whole fish. Total bacterial count (TBC), total volatile basic nitrogen (TVBN), trimethylamine (TMA) and sensory evaluation data revealed no significant differences between whole and dressed fish. Salmonella sp. were not detected in 3 kGy-irradiated samples whereas 2 kGy destroyed Vibrio parahaemolyticus and Staphylococcus aureus. Listeria monocytogenes and Yersinia enterocolitica were not detected but non-pathogenic species such as L. grayi, L. murrayi, and Y. tuberculosis were present in the fish prior to irradiation. Irradiation doses of 2 and 3 kGy destroyed Yersinia sp. and Listeria sp., respectively. These organisms were not detected during storage of the treated fish.