Drought Effects on the Marketable and Nutritional Quality of Carrots

In two cultivars of carrots (Daucus carota L) drought stress was imposed at different developmental stages in order to examine how the marketable and nutritional quality was influenced. Experiments were conducted on both a sandy loam soil and a coarse sandy soil. Although drought stress during a 3-week period at any growth stage reduced total tap-root production, the yield of marketable tap roots increased on the sandy loam soil when drought stress occurred just prior to harvest. This was the result of a decrease in the proportion of split roots when drought stress was imposed during this period. An increased risk of infection by common scab (Streptomyces scabies) was seen when drought stress occurred during early growth. Cultivar differences in susceptibility to split roots and common scab were observed. Significant differences in chemical composition between cultivars were seen. However, drought stress imposed at a specific growth stage did not influence the chemical composition of tap roots in any consistent manner. When drought stress occurred during early growth on the coarse sandy soil the concentration of dry matter was low and that of potassium and nitrate high. However, the opposite was found on the same soil when drought stress occurred just prior to harvest. Averaging the effect of drought periods and cultivars, drought stress was observed to increase the concentration of sucrose in tap roots from the sandy loam soil and decrease that of phosphorus in tap roots from the coarse sandy soil. Various effects on magnesium, β-carotene and vitamin C were detected. Severe drought stress increased the storage losses due to the development of diseases. © 1997 SCI     

反复冻融对泰州芋头淀粉品质特性的影响

本文以泰州地区三种芋头为原料,采用氨水提取芋头淀粉,研究-18 ℃冷冻24 h,25 ℃解冻1 h(反复冻融0、5、10次)对其体系性质、微观结构的影响,探讨冻融过程中淀粉品质的变化规律。结果表明,三种芋头淀粉颗粒表面形态的破坏程度随着冻融次数的增加而增大;冻融次数越多,其稳定性越差,三种品种相比,冻融稳定效果:靖江香沙芋 > 泰兴香荷芋 > 兴化龙香芋。冻融处理使淀粉凝胶硬度、弹性、咀嚼性增加,最后趋于稳定,黏性随冻融次数的增加呈递减趋势。随着样品冻融次数的增加,兴化龙香芋的起始糊化温度、峰值糊化温度、终点糊化温度比同等条件下的泰兴香荷芋、靖江香沙芋高。三种芋头淀粉的膨润力随着温度的升高而逐渐增大,随着冻融次数的增加,每种芋头淀粉的膨润力和凝沉性呈现下降的趋势。因此,随着冻融次数的增加,芋头淀粉品质下降。     

电场对蒸馏水、豆腐冻结与解冻过程的影响

对蒸馏水和豆腐在电场作用下的冻结和解冻过程进行了研究。由实验结果可以看出：在实验条件下电场对蒸馏水冻结和熔化过程（冰水共溶）中蒸馏水中心温度的变化影响不明显,对豆腐冻结和解冻过程中试样中心温度的变化影响也不明显,但施加电场后豆腐在冻结过程中,其外观形状发生了变化：表面细腻、不破裂。在豆腐的底部与容器（培养皿）之间发生了翘起,其原因可能是在电场作用下,豆腐中的水分向豆腐的上表面发生了迁移。因此,有必     

软冷冻条件对动物性食物营养成分的影响

为评价软冷冻条件对动物性食物储存的影响，选择动物性食品为研究样品，观察在软冷冻（-7℃）和传统冷冻（-18℃）条件下，食物的外在表观变化和营养成分的变化。结果表明，在适宜的短期储存条件下，软冷冻可以达到人们对食物储存的保鲜要求，而且保持食物的营养素水平。该研究为软冷冻冰箱的开发和研究提供了科学依据。     

Dispersion Stability of O/W Emulsions with Different Oil Contents Under Various Freezing and Thawing Conditions

Freezing and thawing of oil‐in‐water (O/W) emulsion‐type foods bring about oil–water separation and deterioration; hence, the effects of freezing and thawing conditions on the destabilization of O/W emulsions were examined. The freezing rate and thawing temperature hardly affected the stability of the O/W emulsion. O/W emulsions having different oil fractions were stored at temperatures ranging from –30 to –20 °C and then thawed. The stability after thawing depended on the storage temperature, irrespective of the oil fraction of the emulsion. A good correlation was found between the time at which the stability began to decrease and the time taken for the oil to crystalize. These results indicated that the dominant cause for the destabilization of the O/W emulsion during freezing and thawing is the crystallization of the oil phase and that the effects of the freezing and thawing rates on the stability are insignificant.     

Effects of genotype, soil type, year and fertilisation on sensory and morphological attributes of carrots (Daucus carota L.)

BACKGROUND: The aim of the study was to investigate the effects of variety, soil type and fertilisation, and the interactions between these factors, on yield and quality traits of carrots. RESULTS: Optimum fertilisation levels for yield and quality of grade one roots were found to be between 80 and 160 kg ha^?1 for nitrogen and between 0 and 120 kg ha^?1 for potassium depending on soil type and precipitation. Carrots grown in peat soil had the highest score for sweetness and the lowest scores for negatively associated characteristics such as bitterness, earthy flavour, terpene flavour and firmness. Nitrate content and the amounts of splitted and forked roots were lowest on sandy soil. Variety significantly affected number of grade 1 roots, dry matter, nitrate content and most of the sensory attributes tested. Interactions between variety, soil type and nitrogen fertilisation were found for most of the tested quality characteristics. CONCLUSION: The investigations showed that year and variety had the highest impact on the carrot quality attributes studied, whereas soil type and fertilisation had less influence. Peat soil and moderate fertilisation with N and K gave optimal sensory quality while sand soil gave optimal quality as regards morphological characters like splitting and forking of roots as well as nitrate content. Copyright © 2012 Society of Chemical Industry     

反复冻融对缠丝兔加工过程中脂肪酸含量变化的影响

以反复冻融兔肉为原料,分析缠丝兔加工过程中的脂肪酸含量变化。结果表明：与新鲜原料兔肉对照,随着冻融次数增加,反复冻融原料兔肉及其腌制后和烘烤后的脂肪含量显著降低,硫代巴比妥酸值显著增加（P＜0.05）;原料兔肉检测出棕榈酸（C16∶0）、亚油酸（C18∶2）等脂肪酸,在缠丝兔加工过程中,脂肪降解产生了油酸（C18∶1）;反复冻融兔肉在腌制和烘烤后的脂肪酸也呈显著性变化（P＜0.05）;5 次冻融原料的缠丝兔脂肪含量最低（0.023 8%）、硫代巴比妥酸值最高（0.216 8 mg/kg）。表明兔肉反复冻融对缠丝兔的脂肪酸含量影响显著。     

食品在高压静电场中冻结、解冻的实验研究

微能源在食品工业中的应用日益广泛,本文以马铃薯为研究对象,研究了不同场强对食品冻结,解冻过程和解冻后质量的影响,主要考察冻结曲线,解冻曲线、质地特性,液汁流失几方面。研究发现高压直流电场场强对马铃薯冻结过程,及其以后的无电场解冻过程,冻结食品在电场下解冻过程都有很大影响。不同场强对马铃薯解冻后的质地特性、液汁流失影响较小。     

气质联用法测定反复冻融畜禽肉中胆固醇及其氧化物含量

本文以畜禽肉中胆固醇及胆固醇氧化物、水分、丙二醛指标变化,考察了反复冻融对畜禽肉品质的影响。采用气相色谱-串联质谱/质谱(GC-MS/MS)测定方法,对反复冻融7次(新鲜肉记为冻融0次)后鸡肉、猪肉和牛肉中胆固醇及5种胆固醇氧化物(25-羟基胆固醇、7β-羟基胆固醇、20α-羟基胆固醇、5α,6α-环氧化胆固醇、7-酮基胆固醇)的含量进行了测定。结果表明,随着冻融次数的增加,胆固醇含量逐渐降低,其中牛肉中的胆固醇含量减少尤为明显(减少量为32.47 μg/g)。在反复冻融的过程中,胆固醇氧化物的含量先逐渐增加,后趋于平稳,其中鸡腿肉中7β-羟基胆固醇含量增加最多(增加量为0.601 μg/g)。同时,通过对畜禽肉中脂质过氧化过程中的水分含量和丙二醛含量进行考察,鸡胸肉中的水分减少最多(减少量为14.472 g/100 g),牛肉中的丙二醛增加量最多(增量为1.004 μg/g)。反复冻融会导致畜禽肉胆固醇氧化增加,品质下降。     

Effect of Freezing, Thawing, Drying, and Cooking on Carotene Retention in Carrots, Broccoli and Spinach

Effects of freezing, thawing, cooking and drying on carotene retention of carrots, broccoli and spinach were evaluated. Relative differences in carotene retention among these vegetables were compared. Dehydration, regardless of drying method, significantly reduced carotene in these vegetables. Carotene contents of fresh, vacuum and microwave dried samples for carrots, broccoli and spinach were 989, 459, 368; 106, 43, 40; and 455, 325, 314 μg/g, respectively. Lag time after thawing decreased mean carotene of vegetables significantly in a quadratic manner. Degradation of carotene was severe 6 hr after thawing, Cooking did not affect carotene and cooked samples contained 2.0, 2.9, and 1.2 times more carotene than the respective dehydrated vegetables. Destruction of carotene was relatively lower when initial concentrations were low.     

速冻肉馅在冻融过程中细菌动态变化研究

为了确定速冻饺子在冻融过程中影响其品质变化的关键因素,本实验按一定的工艺进行速冻肉馅加工,于-18℃冻藏,在冻融条件下研究速冻肉馅冻融过程中的细菌的动态变化。结果表明,乳酸菌、肠杆菌和假单孢菌均能在冻融条件下很好的生长,乳酸菌数一直明显高于肠杆菌和假单孢菌总数;速冻肉馅在第16d即第三次冻融时感官品质发生明显变化,此时细菌总数和乳酸菌总数增加极显著,分别为4.1332lgCFU/g和3.9529lgCFU/g,是产品中主要的优势菌,为保证肉馅正常的货架期,其冻融次数不宜超过3次。     

Freezing and Thawing Conditions Affect the Gel Stability of Different Varieties of Rice Flour

The freeze‐thaw stabilities of three different rice flour gels (amylose rice flour with 28% amylose, Jasmine rice flour with 18% amylose and waxy rice flour with 5% amylose) were studied by first freezing at –18 °C for 22 h and subsequent thawing in a water bath at 30 °C, 60 °C and 90 °C, or by boiling in a microwave oven. The freeze‐thaw stability was determined for five cycles. Starch gels thawed at higher temperature exhibited a lower syneresis value (percent of water separation) than those thawed at lower temperature. Amylose rice flour gels gave the highest syneresis values (especially at the first cycle). The Jasmine rice flour gels gave a higher syneresis value than the waxy rice flour gel. Except for freezing by storage at –18 °C and thawing at 30 °C, there was no separation of water at any cycle when waxy rice flour gel was thawed at any temperature, irrespectively of the freezing methods used. Cryogenic Quick Freezing (CQF) followed by storage at –18 °C and then thawing (by boiling or by incubation at any other temperatures) gave lower syneresis values than all comparable samples frozen by storage at –18 °C. The order of syneresis values for the three types of rice flour was waxy rice flour < Jasmine rice flour < amylose rice flour. The syneresis values and the appearance of starch gels, which had gone through the freeze‐ thaw process, suggested that the order of freeze‐thaw stability of gels for the three types of rice flour was waxy > Jasmine > amylose rice flour.     

Comparative study: Thermal and non-thermal treatment on enzyme deactivation and selected quality attributes of fresh carrot juice

The combined effect of emerging electro-technology high-voltage cold plasma (HVCP) and non-thermal ultra-high hydrostatic pressure (UHP) as bioprocess technologies on the quality and stability of carrot juice has been evaluated. Carrot juice was treated with HVCP (70 kV for 3 min), UHP (300, 400, and 500 MPa) at 25 °C for 5 min, and a blanched sample of 100 °C for 5 min (BS) was also prepared. As compared to control and single treatments, the combined treatment (HVCP-UHP500) has attained better results in terms of enzyme inactivation and electroporation extraction of coloring compounds, phytochemicals, and ascorbic acid. Wherein, the maximum of 25.87 ± 0.12^a µg/100 mL of β-Carotene, 11.89 ± 0.80^a GAE (µg g⁻¹) of total phenols, and 24.07 ± 0.12^b mg/100 mL of ascorbic acid content in carrot juice were also observed in the combined treatment at 500 MPa. In addition, phytochemical enhancement might be attributed to the disintegration of phenolic dimers into simple aglycones, predominantly because of the electro-kinetic phenomenon of HVCP, which is subsequently intensified by UHP treatment. Therefore, the current study suggests that the combination of two novel techniques is a highly efficient method in terms of energy, time, and cost, with low yield efficiency and bio-safety.     

浸泡保脆工艺的优化对老山芹解冻后品质的影响

为探究浸泡保脆工艺对老山芹解冻后品质的影响,本试验以老山芹为原料,以溶出钙量及脆度和咀嚼性为指标,从六种保脆剂中筛选保脆剂,对样品进行低温热浸泡保脆处理,并以保脆剂复配比例、保脆剂浓度、浸泡时间为考察因素,采用响应曲面法优化浸泡保脆工艺条件。结果表明,最适合老山芹的保脆剂为海藻酸钠-氯化钙复配型保脆剂,最佳工艺条件为:保脆剂复配比1:1.8,保脆剂浓度(以浸泡液计)4 g/L,浸泡时间29 min,此时老山芹中溶出钙含量为98.93 mg/100 g,较未处理样品显著增加(P<0.05),脆度和咀嚼性也较其他条件显著提高(P<0.05),且溶出钙含量与脆度和咀嚼性呈现极显著正相关(P<0.01,相关系数0.792)。以氯化钙-海藻酸钠低温热浸泡老山芹,可有效保持其解冻后外观品质和口感。     

Freezing, thawing and cooking effects on quality profile assessment of green beans (cv. Win)

Results are presented of the effect of freezing followed by thawing (air and water immersion, both at environmental temperature) and cooking (traditional boiling in a covered pot) on quality profile (in terms of objective texture, colour, chlorophylls and pheophytins and sensory attributes) and structure of green beans (cv. Win). Freezing was carried out at three different rates by forced convection with liquid nitrogen vapour. Kramer shear cell (KSC) and Warner–Bratzler (WB) tests were used for objective assessment of the texture. The highest parameter values occurred in beans frozen at the highest rate and air-thawed at the slowest rate. Also, minimum alteration of the rheological behaviour of cooked beans was achieved by freezing at the highest rate. The best parameter for assessing the texture of frozen green beans after thawing and cooking was the Warner–Bratzler slope (S _WB). Coefficients of softening estimated for S _WB in the thawed beans showed that the texture of the beans frozen at −24 °C was almost four and almost five times softer than that of the beans frozen at −70 °C, for air and water thawing respectively. Frozen and thawed green beans were darker than fresh control, whereas freezing prior to cooking produced lighter-coloured beans than direct cooking. The freezing rate affected colour parameters differently depending on the process that followed. When beans were thawed, increasing the freezing rate produced lighter-coloured beans, whereas when beans were cooked, increasing the rate produced darker-coloured beans. No difference was found in sensory assessments between cooked samples frozen at −24 °C, −35 °C and −70 °C, which probably reflects the panellists' mixed preferences for quickly and slowly frozen samples. Scanning electron microscopy (SEM) revealed different degrees of mechanical damage to tissue structure, which accounted for the rheological behaviour of the beans.     

The role of volatile compounds on aroma and flavour perception in coloured raw carrot genotypes

Quantitative analyses of volatile compounds isolated from raw carrots were combined with sensory analysis in order to identify the role of these compounds on aroma and flavour perception in coloured carrots. A sensory map of carrots with different colours was developed, the content of the isolated volatiles was determined and the role of these compounds for harsh flavour perception in raw coloured carrots was evaluated using multivariate data analysis. The sensory map showed that the coloured carrots formed distinct groups within the sensory profile. The orange genotypes were characterised by having significantly higher intensities in carrot flavour and aroma, while the reverse was true for the yellow genotypes. The purple genotype was characterised by having significantly higher intensity in sickenly sweet flavour and nutty flavour, and the red genotype was characterised by having significantly higher intensities in green aroma and flavour, bitterness and burning aftertaste. From the multivariate data analysis it was concluded that the isolated terpenes do correlate to the harsh flavour attributes.     

黄鳍金枪鱼块常用解冻方法的比较

为获得金枪鱼块的较适解冻方法。比较常用解冻方法对金枪鱼块的影响,包括自然空气解冻、冷藏库解冻、温盐水组合解冻、静水解冻。测定解冻时间以及解冻后72h 内鱼肉色泽、剪切力、pH 值、菌落总数和感官指标的变化。综合这5 个指标得出,温盐水组合解冻能更好地保持金枪鱼的品质,解冻后得到的鱼块a* 值为12.30,剪切力为342.48g,感官得分12.80,且在贮藏48h 内卫生指标均在行业标准范围之内。其中,色泽和剪切力能更好地表征金枪鱼肉品质的变化。     

宰后不同时间冻结对猪肉保水性和组织结构的影响

采用配对试验设计方法研究了宰后45 min和宰后4 h冻结肉样在冻结损失、解冻汁液流失、蒸煮损失、加压失水率、蛋白溶解度、pH、剪切力和组织结构变化等方面的差异,结果显示:(1)宰后45 min冻结的肉在总的冻结和解冻损失、解冻汁液流失和蒸煮损失方面均显著小于宰后4h冻结的肉样(P<0.05)。宰后45 min冻结肉样在加压失水率和冻结损失方面无显著差异(P>0.05)。(2)肌浆蛋白溶解度宰后45 min冻结的肉显著高于宰后4 h冻结的肉(P<0.01)。而总蛋白溶解度和肌原纤维蛋白溶解度则都是宰后45 min冻结的肉低于宰后4 h冻结的肉。(3)宰后45 min冻结肉样的pH显著高于宰后4 h冻结的肉样(P<0.01)。(4)随着宰后时间的延长,未冻结肉样的肌细胞外空隙面积明显增大。(5)宰后45 min冻结的肉样比宰后4 h冻结的肉样的冰晶分布更均匀,相对来说其冰晶也较小一些。     

Effect of Sugar and Nitrogen on the Production of Anthocyanin in Cultured Carrot (Daucus carota) cells

ABSTRACT: Callus cultures of carrot, Nentes scarlet - 104 variety, were initiated on MS medium for anthocyanin production. Two anthocyanins, cayanidin-3-lathyroside and cyanidin-3-glucoside, PRESENT in the ratio of 3:1, were identified in the callus cultures. Eight sugars were tried as carbon source for the production of total anthocyanin. The sugars xylose and lactose, although they initiated growth of the green callus, did not initiate anthocyanin pigmentation. Fructose, galactose, and maltose produced less than 1.75% (dry weight basis) anthocyanin though there was growth of the pigmented callus. Glucose and sucrose produced 3.5%. It was observed that 7.5% sucrose in the medium produced maximum amount of anthocyanin (6.5%). Total nitrogen at 70 mM concentration and a 1:4 ratio of ammonium to nitrate yielded maximum cell growth and best anthocyanin production. Modifying the medium it was possible to enhance the production to 6-8%.