茶多酚处理对冷藏养殖大黄鱼品质的影响

研究了经过0.2%茶多酚浸泡的养殖大黄鱼和对照组在4℃冷藏条件下25d内品质的变化。定期分析了处理组和对照组大黄鱼样品的感官特征、微生物指标（菌落总数）和化学指标（pH、TVB-N、K值）。结果表明,在冷藏过程中茶多酚处理能延长大黄鱼货架期7~8d,在货架期终点15d时,茶多酚处理组和对照组样品的细菌总数分别为10^6.12CFU/g和10^7.45CFU/g,pH值分别为6.78和6.84,TBA值分别为0.122mg/kg和0.168mg/kg,TVB-N分别为166.6mg/kg和318.7mg/kg,K值分别为27.10%和43.72%。可见,茶多酚在大黄鱼冷藏保鲜过程中能有效地抑制细菌繁殖,并减缓脂肪氧化,从而延长了大黄鱼的货架期。     

热处理对新鲜椰肉贮藏特性的影响

针对新鲜椰肉在贮藏过程中极易发生腐败变质的问题，研究不同热处理条件对椰肉贮藏特性的影响，筛选最佳的热处理条件。结果表明，60 ℃、25 min热处理结合低温贮藏，能够有效延缓椰肉的腐败变质，显著降低贮藏过程中椰肉的菌落总数、pH值以及内部脂肪的酸价和过氧化值，同时该热处理条件不会对其质构特性产生影响，椰肉的硬度与对照组无显著性差异。     

传统非发酵豆制品贮藏过程中微生物变化及预测模型初建

分析了5、15和25℃3个储存温度下,白豆干和薄百叶的理化指标、微生物指标以及感官变化规律,并以豆干菌落总数建立初级预测模型。结果表明,在储藏过程中白豆干和薄百叶水分、蛋白质、脂肪、挥发性盐基氮含量基本保持不变;储存温度越高,白豆干pH变化越明显,随着时间延长,pH呈明显下降趋势;不同温度的储存过程中变化不明显;白豆干和薄百叶在不同储藏温度下的菌落总数变化趋势相同,随储藏温度的升高,微生物的生长速率明显上升;5℃条件下,白豆干和薄百叶的货架期不能超过4 d,15℃条件下,白豆干和薄百叶的货架期不能超过1 d;25℃条件下,货架期只有5 h。通过比较线性方程和修正的Gompertz方程建立的初级模型得知,修正的Gompertz方程所得的决定系数R2均超过0.98,模型的可靠性较线性模型高。     

两个鹤蕉切花品种的贮藏保鲜技术

在室内空气相对湿度为80%～85%、温度为18～28℃的条件下,研究'巧舞女'(Choconian Dancer)和'阳光'(Strawberries and Cream)2个鹤蕉(Heliconia psittacorum Linn.)品种的切花贮藏保鲜技术.结果表明:鹤蕉‘巧舞女'预处理以花枝在浓度为1 mmoI/L的STS中浸泡10min的效果最佳,贮藏寿命较对照的延长了6.5 d;瓶插处理以处理组合3 g,L蔗糖+400 mCL 8-HQ(8-Hydroxyquinoline)+2 mg/L 6-BA的保鲜效果最佳,瓶插寿命较对照的延长了7 d.鹤蕉‘阳光'预处理以1 mmol/L SiX3浸泡8 min的贮藏效果最佳,贮藏寿命比对照的延长了4.5 d;瓶插处理以处理组合2g/L,蔗糖+200mg/L 8-HQ+2mg/L 6-BA的保鲜效果最好,瓶插寿命较对照的延长了5 d.说明鹤蕉品种间的贮藏和瓶插寿命存在一定的差异.     

茶多酚浸泡大黄鱼片真空包装0℃贮藏期间品质变化特性

研究了经过0.2%茶多酚浸泡的大黄鱼片和对照组在0℃冷藏条件下20d内品质变化特性。定期分析了处理组和对照组大黄鱼片样品的微生物指标（菌落总数）和理化指标（pH、MDA、K、MetMb、Mb、Caspase-3）。结果表明,冷藏过程中茶多酚处理能够降低化学指标活性,抑制微生物的生长,保持和延长鱼片保质期。因此,在0℃真空包装冷藏保鲜过程中茶多酚处理能更长时间保持大黄鱼片的良好品质。     

充氮小包装茶货架保鲜期研究

以西湖龙井、黄山毛峰和安溪铁观音充氮小包装茶为原料,利用加速破坏性实验模型,分别在30C、40C和50C条件下进行35d的货架期贮藏试验,每隔5d对样品进行感官审评和生化成分检测。研究结果表明,在试验过程中叶绿素含量明显下降,维生素C在50C下含量下降明显,茶多酚总量贮藏前后无明显变化。在试验期间,感官品质30C贮藏西湖龙井和黄山毛峰均无明显陈变;40C贮藏西湖龙井货架期为30d,黄山毛峰货架期为25d;50C贮藏西湖龙井和黄山毛峰货架期均为10d。加速破坏性实验中西湖龙井的Q10值为3;黄山毛峰Q10值为2．5;因此推算出冷库里存放后取出的2g充氮复合锡箔包装的西湖龙井在30C和25C条件下的货架期约为90天和155天;黄山毛峰的货架期则分别约为62天和98天。铁观音在试验过程中品质无明显陈变。     

不同制粉方法对燕麦粉货架期的影响

为了解不同制粉方式对燕麦粉货架期的影响,以炒制燕麦粉、燕麦片粉、超微燕麦粉为研究对象,以脂肪酸值和丙二醛含量为评价指标,应用Arrhenius相关模型及热力学理论和统计学原理,比较了三种制粉方式生产的燕麦粉货架期。结果表明,三种燕麦粉的脂肪酸值和丙二醛含量均随贮藏时间延长呈上升趋势;50℃贮藏比40℃贮藏上升更明显,燕麦片粉上升的最快。燕麦粉发生氧化产生游离脂肪酸和丙二醛在40℃和50℃均遵循0级反应动力学,根据Arrhenius动力学模型和统计学原理,预测炒制燕麦粉、燕麦片粉、超微燕麦粉在常温(20℃)下的货架期分别为304d、140d、204d。     

不同贮藏温度对桔梗花粉生活力及授粉结实能力的影响

以ME3+BK+100 g/L蔗糖+150 g/L PEG4000作为培养基,把桔梗新鲜花粉在不同的温度下进行培养,结果表明,30℃培养1.5 h为花粉萌发和花粉管生长的最佳培养条件。把桔梗花粉贮藏在不同的温度下,结果显示:低温贮藏可明显延长花粉的寿命,常温下花粉仅能贮藏4 d左右,但在10、4、-20℃下贮藏,花粉寿命可分别达60、90、150 d以上;随着贮藏时间的延长,花粉的授粉结实率均呈下降趋势,但低温贮藏可明显减缓结实率下降的速度。      

茶多酚对冰藏大黄鱼品质及微生物的影响

采用生物保鲜剂茶多酚对大黄鱼进行浸泡处理,研究了大黄鱼在冰藏保鲜过程中品质及微生物的变化。通过测定感官评分值、菌落总数、p H值、挥发性盐基氮(TVB-N值)及硫代巴比妥酸值(TBA值),评价大黄鱼在冰藏过程中品质变化,同时采用16 S r DNA克隆文库及限制性内切酶片段长度多态性(RFLP)技术对大黄鱼在冰藏条件下的腐败菌进行分析。结果表明,在冰藏过程中,茶多酚处理组的菌落总数、p H值、TVB-N值、TBA值均低于对照组,感官评分值优于对照组,大黄鱼在冰藏条件下货架期由12~16 d延长至20~24 d,茶多酚处理组保鲜效果较好。新鲜大黄鱼细菌种类比较丰富,达15种类型,而腐败后细菌种类明显减少,在腐败末期,对照组(20 d)的细菌种类有8种,其中假单胞菌属(Pseudomonas)和希瓦氏菌(Shewanella)为主要腐败菌,所占比例分别为43.7%和39.6%。而茶多酚处理组(24 d)细菌种类较对照组更少,其腐败菌主要为假单胞菌属(Pseudomonas),占细菌总量的76.8%。     

不同微波强度对鲜切西兰花品质的影响

以鲜切西兰花为试材,采用40%P0(320 W)、60%P0(480 W)2种火力分别处理鲜切西兰花1、4、6 s,在室温条件下(18~20℃)贮藏7 d,研究不同微波处理对鲜切西兰花感官品质、失重率、呼吸强度、可滴定酸含量(TA)、维生素C含量(Vc)、叶绿素含量的影响。结果表明:微波处理可明显提高鲜切西兰花的感官品质,降低鲜切西兰花贮藏期间的呼吸强度和失重率,减缓可滴定酸、抗坏血酸含量的下降。其中,480 W微波处理4 s、320 W微波处理6 s保鲜效果最明显,常温下能延长鲜切西兰花的货架期2 d。     

预冷前后1-MCP处理对杨梅采后贮藏品质的影响

本研究以‘硬丝’杨梅为试材,比较预冷前后进行1-MCP处理,及贮藏温度对杨梅采后贮藏品质及货架期的影响。预冷结合1-MCP处理,可延缓贮藏期间杨梅果实单果重、硬度的下降,抑制膜脂过氧化产物MDA含量和呼吸强度的上升,延缓贮藏6 d内果实可溶性糖、可滴定酸含量的降低,但对延缓花色苷含量降解效果不明显。预冷前或后进行1-MCP处理,在延缓果实品质劣化方面并无显著差异。预冷处理可有效降低果实入库时的呼吸强度,但需结合1-MCP处理才能有效维持贮藏期间果实呼吸强度处于较低水平。预冷后1-MCP处理,杨梅果实可贮藏于7 ℃中5 d,出库后,货架期可达5 d,腐烂率<10%,与贮藏于4 ℃中无显著差异,可有效降低冷库能耗成本,贮藏效果优于预冷前1-MCP处理。考虑生产实际,杨梅采后处理应及时装箱,加冰壶,置于4 ℃预冷处理,冷藏运输应控制在5 h以内。入库前使用7 μL/L的1-MCP于4 ℃冷库中熏蒸18 h。贮藏期可置于4~7 ℃冷库中贮藏5 d,于第6天上架销售,货架期可达5 d,具有较好的应用前景。     

不同加工条件对全豆豆腐凝胶强度的影响

针对全豆豆腐加工中豆腐凝胶强度低的问题,研究了全豆豆腐煮浆工艺和凝固工艺中酶添加量、凝固温度、凝固时间和NaCl添加量对全豆豆腐凝胶强度的影响。得出全豆豆浆加热至90℃,保温10min的加热条件下,全豆豆腐凝胶强度最佳。通过单因素和正交实验,得到最佳的凝固条件为：酶添加量1．2U／mL豆浆、凝固温度50℃、凝固时间2h和NaCl添加量0．125％,制得的全豆豆腐品质优良,几乎包含大豆全部营养,比传统豆腐营养更丰富。     

不同真空预冷终温对豆腐品质的影响

研究不同终温（4、6、8℃）时真空预冷对豆腐降温速率、失水率，及其在4℃环境下1W内的蛋白质、持水性、pH值、硬度和色泽等指标的影响。结果表明：终温变化对降温速率和质量损失率无显著的影响，然而，对豆腐的品质（蛋白质、持水性、pH值、硬度及色泽）影响显著。综合比较得知，在压力500Pa条件下预冷终温为4℃的样品品质最优，当贮藏温度为4℃时贮藏期不宜超过5d。     

基于模糊综合评价的柠檬豆腐工艺研究

为研究一种新型天然酸性豆腐凝固剂,以柠檬汁制备豆腐,以感官评价和持水力为指标,采用单因素和正交实验,结合模糊数学评价法优化柠檬豆腐的加工工艺。结果表明:柠檬豆腐的最佳加工工艺组合为豆水比为1∶10,柠檬汁添加量为55%,点浆温度为70℃,养花时间为20 min,此工艺组合下制得的柠檬豆腐有浓郁的豆香味与柠檬香气,无酸涩味,断面光滑细腻,弹性好,持水力最好。     

Effect of steam explosion on enzymatic hydrolysis and baking quality of wheat bran

In this study, the effect of steam explosion (SE) treatment on microstructure, enzymatic hydrolysis and baking quality of wheat bran was investigated. Coarse and fine bran were treated at different steam temperatures (120–160 °C) and residence times (5 or 10 min) and then hydrolysed with carbohydrase enzymes. The SE treatment increased water extractable arabinoxylan (WEAX) content from 0.75 to 2.06% and reducing sugars from 0.92 to 2.41% for fine bran. The effect was more pronounced with increased SE temperature and residence time. The highest carbohydrate solubilisation was observed in fine bran at SE treatment of 160 °C, 5 min. WEAX content increased to 3.13% when this bran was incubated without enzyme, while WEAX content increased to 9.14% with enzyme addition. Microscopic analysis indicated that cell wall structure of wheat bran was disrupted by severe SE conditions. Supplementation of SE treated (150 °C, 10 min) bran at 20% replacement level decreased the baking quality of bread. However SE followed by enzymatic hydrolysis increased specific volume and decreased crumb hardness (on the day of baking and after three days of storage). Phytic acid content of bread supplemented with SE treated bran was lower than the one supplemented with untreated bran.     

Steam treatment to prevent carrot decay during storage

Organically grown carrots (Daucus carota L.) have a relatively short storage and shelf life, mainly because chemical measures cannot be implemented to control plant pathogens. Laboratory experiments demonstrated that steam treatments substantially reduced decay of stored organically grown carrots. Prior to being packaged, winter carrots were exposed to 3 s of steam. After 60 days of storage at 0.5°C plus an additional week at shelf conditions (20°C), 2% of the carrots were decayed, as opposed to 23% in the nontreated control. When carrot was inoculated with the fungi Alternaria alternata, [(Fr. : Fr.) Keissler] A. radicina (Meier) and Sclerotinia sclerotiorum [(Lib.) De Bary], percentages of decay, after similar periods of storage and shelf life, were 5% for steam-treated carrot and 65% for the nontreated control. In semi-commercial experiments carrots were treated with steam during the sorting process, and similar results were obtained. Higher decay was found in spring-grown carrots because of the presence of the bacterium Erwinia carotovora.sub. sp. carotovora     

Shelf life extension of sliced wheat bread using either an ethanol emitter or an ethanol emitter combined with an oxygen absorber as alternatives to chemical preservatives

In the present study, the effect of active packaging [ethanol emitter (EE) or ethanol emitter combined with an oxygen absorber (EE + OA)] on shelf life extension of sliced wheat bread stored at 20 °C was investigated. Bread containing commercial preservatives (WP) and no preservatives (WOP) were taken as controls. Microbiological, physicochemical and sensory changes occurring in the product as a function of treatment and storage time were monitored for 30 days. Counts for yeasts and molds were 5.1, 3.8, 2.0 and 2.0 log cfu/g and for Bacillus cereus 4.7, 2.5, 2.3 and 2.0 log cfu/g for WOP, WP, EE and EE + OA treatments respectively after 30 days of storage. Initial pH 6.3 and 6.4, for WP and WOP samples remained fairly constant irrespective of specific treatment. Aroma quality deterioration during storage was due to the loss of volatile compounds and the formation of “off-flavors” through lipid oxidation. Neither the EE nor the EE + OA had an adverse effect on initial odor, taste and texture of bread. Based on sensory (texture) and microbiological data, shelf life was ca. 4 days for samples WOP; 6 days for samples WP; 24 days for samples containing the EE and at least 30 days for samples containing the EE + OA.     

Changes in β-carotene and ascorbic acid content of fresh amaranth and fenugreek leaves during storage by low cost technique

Leafy vegetables are highly perishable and their shelf life depends on duration and conditions of storage. A low cost storage structure was used to extend the shelf life of amaranth and fenugreek and their quality was evaluated on the basis of retention of -carotene, ascorbic acid and chlorophyll during storage. Losses of -carotene ranged from 46.5 to 85.0% for amaranth and 24.0 to 73.0% for fenugreek depending on duration and conditions of storage. Similarly ascorbic acid retention varied from 9–32% for amaranth and 23–80% for fenugreek. Results showed that the degradation of quality parameters was faster at ambient conditions and packaging of leaves in low density polyethylene bags was beneficial in improving shelf life and nutritive value. Low cost storage structure was similar to low temperature storage for retention of -carotene, ascorbic acid, chlorophyll content and enhancement of shelf life.