贮藏温度对鲜切胡萝卜贮藏品质的影响

研究不同贮藏温度对鲜切胡萝卜贮藏品质的影响。以鲜切胡萝卜为试材,采用0（冰温）、4、7、10℃不同温度进行贮藏,通过测定失重率、可溶性糖、菌落总数及感官评价等指标,探究不同贮藏温度对鲜切胡萝卜贮藏品质的影响。结果表明,冰温贮藏食用贮藏期可以达到16 d,而4、7、10℃分别是12、9、5 d,并基于试验数据,回归了鲜切胡萝卜贮藏期与贮藏温度的关系式,发现两者呈负相关关系,并不符合温度系数Q10的指数规律。综上所述,在0℃（冰温）贮藏条件下能够较好的维持鲜切胡萝卜的贮藏品质及感官     

Effect of Combined Gamma-Irradiation and Storage on Biochemical Changes in Sweet Potato

Sucrose of uncured Red Jewel sweet potato increased from 3.8% to 10.7% after a combined treatment of a 300 Krad dose and 4 days storage at 24°C post-irradiation (PI). Starch decreased from 16.8% to 6.1% after 16 days following a 500 Krad treatment. Phosphorylase, phosphoglucomutase and sucrose phosphate synthase enzyme specific activities increased 2.4-, 1.8- and 1.3-fold, respectively, after 3 days PI following 200 Krad exposures compared to nonirradiated roots. The beta-Amylase, phosphoglucose isomerase and sucrose synthase specific activities increased 1.2-fold. Sucrose synthesis in the irradiated sweet potato was attributed to beta-amylase, phosphorylase, phosphoglucomutase, phosphoglucose isomerase and sucrose synthase.     

有关碱回收系统平衡的若干问题

本文从碱回收的实践与观察出发，论述了系统平衡是提高效率、优化效益的前提，平衡应是积极的平衡。平衡是一个综合性的问题，并提出了应注意的问题与建议。     

Blanching Effects on the Chemical Composition and the Cellular Distribution of Pectins in Carrots

ABSTRACT: Carrots were blanched using 4 time-temperature combinations. Galacturonic acid and sugar contents of pectin extracts were determined, and immunocytochemistry experiments elucidated changes in the cell membrane. Blanching decreased galacturonic acid and total sugar contents for all treatments. Carrots subjected to high-temperature short-time (HTST) blanching contained more total galacturonic acid and total sugars in pectins than carrots blanched for a long time at low temperatures (LTLT). Similar trends were observed for methylated pectin and neutral sugars. Immunocytochemistries showed separation of the 3-way junction of cell walls, and LTLT-blanched carrots showed higher levels of JIM 7-labeled pectin (1.6 × 10⁻⁴ particles/nm²) than HTST-treated carrots (5.9 × 10⁻⁵ particles/nm²).     

Storage and Cultivar Effects on Shear Compression Values and Esterified Cell Wall Phenolics in Carrots

ABSTRACT: Phenolics esterified to cell walls in carrots were found to consist primarily of p-hydroxybenzoic acid with minor contributions from ferulic and vanillic acids and vanillin. These compounds could be indexed by standardized measurement of absorbance at 254 nm. As indexed, esterified cell wall phenolics varied widely between carrot cultivars and increased with carrot storage. These increases were not correlated with increased carrot toughness as determined by measurements in a shear compression cell. Carrot texture was unaffected by the levels of esterified cell wall phenolics present in the tissue.     

Effects of Boiling and Storage on Dietary Fibre and Digestible Carbohydrates in Various Cultivars of Carrots

The influence of boiling and storage on dietary fibre and digestible carbohydrates was investigated in eight different carrot cultivars. The content of total dietary fibre was in the range 252–291 g kg^-1 DW and was generally at the higher end for the early cultivars and at the lower end for the late ones. During storage, there was a decrease in the soluble fibre content in all cultivars and generally an increase in insoluble fibre. Following boiling, the loss of dietary fibre varied considerably between cultivars. After storage, the loss could be correlated to the average root weight of the carrot cultivars. The total content of glucose, fructose and sucrose was rather similar in the various cultivars, whereas their individual distribution differed. Storage had generally minor influence on the sugar content, except in the cultivars Amarant and Bull. On boiling, the loss was solely dependent on the initial sugar concentration. After storage the loss increased, which could be related to the lower dry matter content. The choice of cultivar and storage time is important in interpreting analytical data from carrots and is probably of similar significance in other vegetables when studying effects of heat treatment. © 1997 SCI.     

Calcium Treatments Affect Storage Quality of Shredded Carrots

Carrot shreds, sticks and slices were dipped in solutions of CaCl₂ alone, or with chlorine and stored at 0, 5 or 10°C to determine the effects of calcium (Ca) on storage quality. A 0.5% or 1% CaCl₂ treatment maintained firmness and reduced microbial growth of carrot shreds at all temperatures. These treatments also resulted in lower tissue pH than in the water-dipped controls. Treatments increased Ca content slightly in sticks and slices and substantially in shreds and had no effect on storage quality of sticks or slices.     

High-Pressure-Freezing Effects on Textural Quality of Carrots

Raw or 3 min blanched carrots were pressurized for 45 min at ?18°C ～–20°C and then thawed at 20°C. When carrots were frozen at 100Mpa (ice I), firmness decreased and strain increased. Textural values of carrots pressurized at 200MPa (liquid), 340MPa (ice III), 400MPa (ice V) at ca. –20°C were acceptable. When pressure was increased above 500MPa, the strain increased. Release of pectin and histological damage in carrots pressurized at 200, 340 and 400MPa were less than carrots frozen at 100 and 700MPa (ice VI). After pressurization at 200 and 340MPa at —20°C, carrots were stored in a freezer (–30°C). Firmness decreased and strain increased, but textural values were higher and histological structure were more intact than those frozen at –30°C (0.1MPa) then stored. Thus, high-pressure-freezing at 200, 340 and 400MPa appeared to be effective in improving both the texture and histological structure of frozen carrots.     

Carotenoid Photostability in Raw Spinach and Carrots During Cold Storage

A reverse-phase gradient HPLC method was developed for separating xanthophylls, chlorophylls, carotenes and cisβ-carotene isomers from raw spinach and carrots. The effect of dark and lighted cold storage on pigment stability was studied. Light promoted pigment losses in raw spinach. Degradative losses at 8 days ranged from 60% for violaxanthin to 22% for lutein. Dark, cold storage did not affect carotenoid levels except for all-transβ-carotene which showed an 18% loss at 8 days. In raw carrots, neither lighted nor dark cold storage affected major carotenoids. In spinach, the isomeric distribution of β-carotene showed strong linear correlations between trans and cis forms.     

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     

Effects of Chemical Preservatives on Storage and Nutrient Composition of Soybean Curd

Storage and nutrient composition of soybean curd in immersion solutions were determined. Chemical preservatives (acetic acid or potassium sorbate + acetic acid) in soybean curd immersion solutions maintained low viable cell counts but had little effect on soybean curd nutritional quality during storage at 4–7°C for 21 days. Thiamin and riboflavin in soybean curd decreased (P<0.05) during storage, representing leaching of the vitamins into immersion solutions. After 14 days of storage, soybean curd protein decreased and carbohydrate increased (P<0.05). Decreases (P<0.05) in proline and arginine occurred following 14 days of storage, but no losses were found in remaining amino acids.     

Quality of Shredded Carrots as Affected by Packaging Film and Storage Temperature

ABSTRACT: Different packaging films and storage temperatures were used to establish a range of equilibrium modified atmospheres for storage of shredded carrots. Quality and storage-life of the packaged shredded carrots were determined using sensory evaluation, microbial counts, and a range of physical tests. Minimal processing steps such as peeling and shredding caused physical damage, physiological stress, and enhanced microbial growth, leading to a reduced shelf life when compared to the whole vegetable. A P-plus microporous film (CO₂ permeability of 29 X 10³mL.m ^-2.d ^-1.atm ^-1) was the most suitable for the storage of shredded carrots. Findings indicated that deterioration in these products was triggered by the depletion of oxygen more than by the rise in carbon dioxide.     

Chemical Composition and Color of Strained Carrots as Affected by Processing

The effects of processing line location, holding temperature prior to retorting (82.7, 87.8, and 93.3°C) and retort temperature (118.3, 121.1, and 123.9°C) on chemical composition and color of strained carrots was evaluated. Hunter L, chroma and hue values, and glucose and fructose levels decreased as strained carrots were transferred from batch to holding tanks. Strained carrots held in batch tanks at 93.3°C had less total soluble phenolics, glucose and fructose than those held at 87.8°C and 82.2°C. Carrots retorted at 123.9°C had lower Hunter L and chroma values, and greater levels of total soluble phenolics than those retorted at 118.3 and 121.1°C.     

Gamma-Irradiation Affects Some Physical Properties of Dry Bean (Phaseolus vulgaris) Starch

Gamma-irradiated great northern (GN) bean starch (2.5–20 kGy) showed apparent increased susceptibility to central fissures. Bean damage during scanning electron microscopy was observed using ≥400OX magnification on GN bean starch samples. Approximate molecular weights estimated by gel filtration chromatography Sepharose Cl-2B of control GN bean starch were: amylopectin >2×10⁶ and amylose 2×10⁵. Amylose-like fraction of irradiated bean starch (20 kGy) revealed two peaks ～6.9×10⁴ and 1.5×10⁵ daltons. Differential scanning calorimetry showed an increase in gelatinization enthalpy and a small increase in gelatinization peak temperature at 20 kGy suggesting a reorganization of the crystalline and amorphous phases of the starch granule.     

Water Blanching Effects on Headspace Volatiles and Sensory Attributes of Carrots

Carrots blanched in water for 0 to 300 sec were analyzed for flavor volatiles by dynamic headspace analysis, the volatiles identified by gas chromatography/mass spectrometry, and the sensory attributes evaluated by a trained panel to determine quality changes as related to blanching times. Most volatiles, in particular terpenoids (sabinene, β-pinene, β-myrcene, limonene, trans-caryophyllene, α-humulene, β-bisabolene and α-farnesene) decreased by at least 50% within 60 sec of blanching. Ratings on quality attributes of color, texture, raw carrot aroma, sweetness, flavor and overall impression decreased with blanching time, while cooked carrot aroma increased. There were correlations (p < 0.05) between blanching times, flavor volatiles and sensory attributes.     

食物成分对胡萝卜中滴滴涕生物有效性的影响

采用基于生理学的体外实验,通过模拟人体的胃肠环境,研究不同食品及食用豆油对胡萝卜中滴滴涕(DDTs)生物有效性的影响。结果表明：0.12g 胡萝卜中添加0.12g 菠菜、0.12g 白菜及0.12g 猪肉作为混合食品时,DDTs 的生物有效性明显下降;其中菠菜和白菜使其降幅较大且相近,分别为78.3%～86.1% 和69.8%～78.6%,猪肉使其降幅相对较小,为46.8%～72.7%。而添加0.12g 大米会导致DDTs 的生物有效性增大37.2%～40.0%。添加0.6g 菠菜、白菜、猪肉和大米后,DDTs 的生物有效性较添加0.12g 有不同程度的降低。DDTs 的生物有效性与食品中蛋白质及纤维素的含量呈负相关,与碳水化合物的含量和热量呈正相关。此外,DDTs 的生物有效性随着添加食用豆油量的增大而增大,在油量为50μl 时增长趋势最为明显。     

Effects of Some Chemical and Physical Treatments on Proteolysis in Milk

Addition of either a water-soluble or oil-soluble surfactant to milk enhanced proteolysis. This effect was attributed primarily to alteration in the availability of the casein and secondarily to a partial release of proteolytic enzymes from the milk fat globule membrane. Adding milk fat globule membrane to milk also increased proteolysis, presumably by contributing additional proteinase.Proteolysis increased after milk was subjected to Waring blendor treatment, ultrasonic treatment, or temperature fluctuations. These treatments presumably cause dissociation of proteinases from milk fat globule membranes or casein micelles.Addition of carrageenan to milk inhibited proteolysis. Carrageenans may inhibit proteolysis by preventing dissociation of casein micelles or by blocking access to the active sites on casein. Removing either calcium ions or colloidal phosphates from milk by dialysis enhanced proteolysis. This enhancement may be due to dissociation of casein micelles or milk proteinases originally adsorbed on the casein micelles. Removal of calcium ions increased proteolysis more than removal of colloidal phosphates.     

Cryoprotective Effects of Some Materials on Cod-Surimi Proteins during Frozen Storage

Freeze-induced protein denaturation of cod surimi was studied as affected by carbohydrates (sucrose and glucose syrup at 8% w/w), polyols, (sorbitol and glycerol at 8% w/w), protein hydrolysates (fish protein and casein hydrolysates at 4% w/w), hydrocolloids (pectin-1% w/w, sodium alginate, lambda- and iota-carrageenan-0.5% w/w) and combinations of the above, (sucrose/sorbitol 1:1 mixture at 8% w/w, or combined with protein hydrolysates at 4% w/w). Salt extract-able protein (SEP) and heat induced denaturation by differential by differential scanning calorimetry (DSC) were used to monitor protein changes in surimi stored 16 wk at -20°C. The best cryoprotection effect was achieved from sorbitol, glucose syrup (DE = 60), sucrose and sucrose/sorbitol 1:1 w/w mixture at 8% w/w in surimi. Correlations between certain DSC parameters and SEP were high.     

Effects of Gamma-Irradiation on Flatulence-Causing Oligosaccharides in Green Gram (Phaseolus Areus)

Effects of gamma-irradiation (l–10 kGy) on flatulence-causing oligosaccharides of green gram were investigated. Irradiation at 2.5 kGy of hydrated seeds caused nearly 20% loss in their total content; but, 50% each of stachyose and raffinose, the two most gas-forming sugars, was reduced. However, oligosaccharides disappeared completely from germinated (48 hr) seeds, irradiated at 2.5–10 kGy; though α-galactosidase activity was not changed. When irradiated green gram flour was subjected to enzymic hydrolysis, significantly more reducing sugars were liberated. Quantitative analysis of the breakdown products of raffinose also suggested that radiation treatment stimulated the glycosidic cleavage of higher sugar molecules to simpler, easily digestible sugars. Thus radiation treatment of green gram is effective for elimination of oligosaccharides during germination.