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1.
离子交换纤维在碳法甘蔗糖汁脱色中的应用   总被引:9,自引:0,他引:9  
研究了聚丙烯基强碱性阴离子交换纤维对碳酸法糖厂糖汁的脱色性能。考察了糖汁温度、流速等因素对脱色效果的影响。结果表明 ,与离子交换树脂相比具有脱色容量高、脱色速度快、再生速度快和抗污染能力强等优点。阴离子交换纤维对二清汁的脱色效果明显 ,处理量为 2 75mL/ g ,脱色后清汁色值低于 1 0°St。 70~ 80℃时脱色和解吸效果最好 ,经纤维脱色后清汁可以满足制备精制糖的要求  相似文献   

2.
Initially, a technical screening was applied to select yeasts with a potential for trehalose production using thermal stress for the induction of synthesis. The effects of the concentrations of sugar cane molasses, corn steep liquor and a commercial yeast extract Prodex Lac SD®, and of pH and temperature on the biomass were studied using a fractional design followed by a central composite rotatable design (CCRD). The optimum values were 50 g/l for the molasses and corn steep liquor concentrations, initial pH of 5.5, and temperature of 30 °C, with no yeast extract. Under these conditions, the production of trehalose was studied using a CCRD to optimize the temperature (33 to 47 °C) and exposition time (60 to 120 min) of the cultures to the thermal stress. The maximum intracellular trehalose content reached was 20.5% (g trehalose/100 g dry cell) at temperatures of 35–40 °C and with 100–120 min of exposition time to the thermal stress.  相似文献   

3.
The effects of pretreatment temperature on the retention and denaturation of protein were studied in relation to moisture removal from lucerne forage subjected to mechanical pressing. Leaf samples were held for 5 min at a temperature between 40-100°C, then pressed. Although the protein concentration of the expressed juice decreased with increasing temperature, the amount of soluble protein lost in the expressed juice was fairly constant, amounting at most to only 4%. The maximum reduction in water content (76 ± 1%) was achieved by pressing after a treatment of 60-70°C. However, the protein retained in the residue was not denatured completely until the pretreatment temperature exceeded 80°C. At 60°C, with maximum water removal, only one-third of the protein became denatured; at 50°C, 80% of the maximum water removal was obtained with only 16% denaturation of retained protein.  相似文献   

4.
Fenton oxidation has been used to study the degradation of caffeic acid (CA), a colour precursor in sugar cane juice, in water and sucrose solutions. Central composite design and response surface methodology were used to evaluate the relationships between % CA degradation and the process parameters (i.e. CA and sucrose concentrations, pH, reagent dosages, reaction temperature and time). A quadratic polynomial model was developed for CA degradation and indicated that the initial sucrose and CA concentrations significantly affected the amount of CA degraded. Numerical optimisation was used to determine the optimum process parameters. It showed that in water at 35 °C, 80% CA was degraded at pH 5.49, 0.72 mm Fe2+ and 9.44 mm H2O2. However, in a synthetic sugar solution under similar conditions to that of factory mixed cane juice containing 13 mass% sucrose, only 61% of CA was degraded.  相似文献   

5.
为了稳定并进一步提高锅炉烟道气CO2饱充混合汁的澄清工艺应用效果,本文通过使用自制饱充设备,进行单因素与正交试验,分析饱充温度、饱充pH值、饱充时间及烟道气CO2浓度等对胶体去除率、清混汁纯度差、清汁色值及钙盐含量的影响,优化混合汁C02饱充工艺。结果表明饱充温度、饱充pH值、饱充时间及烟道气CO2(v/V)浓度对澄清效果有明显影响,饱充温度、饱充pH值及饱充时间均存在一最佳值;CO2浓度越高,澄清效果越理想,当浓度低于12%时对混合汁进行饱充澄清意义不大;最优工艺组合为饱充温度50℃,饱充pH11.0,饱充时间8min,CO2浓度22%。  相似文献   

6.
Purification of the sugar beet juices obtained by novel low temperature extraction (at 30 °C) assisted by pulsed electric field (PEF) and conventional high temperature extraction (at 70 °C) was done by the method of lime-carbon dioxide treatment. The total concentration of lime used for the purification was varied from 6 to 15 kg of CaO/m3 of the juice. Filtration properties of the juices of first carbonation, as well as purity and coloration of the final thin juices, were compared. It was observed that purification of the juice extracted at 30 °C results in faster filtration of the juice of first carbonation and lower coloration of the final thin juice as compared to the juice obtained by means of purification of the juice extracted at 70 °C. It suggests that the quantity of CaO required for the efficient juice purification may be decreased from 15 kg/m3 (for the juice extracted at 70 °C without PEF treatment) to approx. 8 kg/m3 (for the juice obtained by PEF-assisted extraction at 30 °C).  相似文献   

7.
Alternative process of sugar beet transformation is investigated by tuning experimental conditions. A three-step process has been set-up: (1) sugar beet cossettes pretreatment by pulsed electric field (PEF) and (or) short preheating to different temperatures; (2) extraction of juice from pre-treated cossettes by pressing; and (3) purification of the expressed juice by ultrafiltration. The PEF treatment was applied to cold (10 °C) and preheated (to 20, 50, 60, 70, and 80 °C) sugar beet cossettes with intensity of E?=?600 V cm?1 using rectangular monopolar pulses of 100 μs during t PEF?=?5–20 ms. Experiments were performed with cossettes of three sizes. Control experiments were done without PEF treatment using cold (10 °C) and preheated (to 20–80 °C) cossettes. PEF-treated and (or) preheated cossettes were pressed at 5 bars during 15 min. Afterward, expressed juices obtained from the PEF-treated cossettes at 20 °C and from the untreated ones at 80 °C were purified by dead-end ultrafiltration with stirring (500 rpm) at the temperature of 20 °C by using polyethersulfone membrane with MWCO of 30 kDa. Application of PEF (E?=?600 V cm?1, t PEF?=?10 ms, T?=?20 °C) with following pressing of cossettes at 5 bars during 15 min permits to obtain the juice yield Y?=?66,5 %, which is equivalent to that obtained from cossettes preheated to 80 °C and untreated electrically (Y?=?64 %). The energy consumption of cold PEF treatment (≈2–3 Wh/kg) is very attractive as compared to preheating at high temperatures (≈138–194 Wh/kg). Combination of thermal and electrical pretreatments leads to additional softening of sugar beet tissue and to a slightly higher (on 5–10 %) juice yield, but the electroporation of preheated cossettes is more energetically costly. The raw juice expressed from PEF-treated cossettes at 20 °C has higher purity (93.5 %) than juices expressed at 50 °C (92.9 %) and at 80 °C (92.3 %). The temperature increasing from 20 to 80 °C results in a higher juice coloration (5680 IU at 20 °C and 7820 IU at 80 °C) and leads to a higher (on about 35 %) colloids concentration in the expressed juice. The filtrate obtained from the juice expressed at 20 °C with PEF treatment has a higher purity (96 %) than the filtrate obtained from the juice expressed at 80 °C (95.3 %) and its coloration is considerably lower (330 IU versus 1930 IU). In addition, the quantity of proteins and colloids in the filtrate of juice expressed at 20 °C is lower than that in the filtrate of juice expressed at 80 °C  相似文献   

8.
A batch Ohmic heater (5 L) with a modified electrode arrangement was designed for quick and uniform heating of kinnow juice. A T-shaped arrangement and micro silver coating over stainless steel electrodes provided temperature variation of 0–2 °C across the system and a system performance coefficient of 0.96. The come-up time for 60–80 °C was 1.3–3 min at 180 V. Pectin methylesterase, the most resistant enzyme, was inactivated completely at (120 V/80 °C/1 min), (150 V/80 °C/30 s), (180 V/70 °C/10 s). No aerobic mesophiles, yeasts, and moulds were detected in these samples. Ohmic heating at 180 V did not influence the colour of the juice significantly; however, some samples showed a little elevation (by 0.2) in the pH. The reduction in vitamin C, antioxidants, and total phenols was 6–12% at 150 V/80 °C/30 s. The fuzzy analysis shows that the Ohmic pasteurized juice had the highest similarity score.Industrial relevancesA batch assembly (5 L capacity) of the Ohmic heater has been fabricated to make a shelf-stable kinnow juice. The produced juice is microbially safe, enzymatically stable, and retains maximum bioactive compared to conventional thermal treatment. Thus, Ohmic heated juice can fulfill the stakeholders' demand for microbial safety, enzymatic stability, and nutritional superiority. Industry can scale up the design of batch Ohmic heater for efficient and faster pasteurization of citrus juice like kinnow juice.  相似文献   

9.
Carrot juice was prepared from each of yellow-, orange-, and purple-coloured carrots. Juice preparation included sorting, washing, peeling, acid-blanching, chopping, juicing, sterilization, and bottling steps. Bottled juices were stored in incubators which were kept at 5 °C, 20 °C, and 27 °C. Analytical determinations of pH, total soluble solids, maximum absorbance, reducing sugar, ascorbic acid, and β-carotene were made in suitable time intervals. Each of the three types of carrot juice kept at 27 °C deteriorated organoleptically in the first two weeks of storage. Juices stored at 20 °C and 5 °C were stable up to seven and twelve weeks, respectively. It was concluded that each of the carrot species can well be used for the preparation of carrot juice.  相似文献   

10.
This study investigated the optimum conditions, including pH, temperature, incubation time, and enzyme concentration, for the enzymatic manufacture of citron waste juice by pectinase and cellulase using response surface methodology (RSM). A central composite design was used as an experimental design for the allocation of treatment combination. The highest yield was 71.1% at pH 5.00, 51.15°C, 53.74 min, and 0.44%, whereas the lowest turbidity was 0.20 at pH 4.87, 50.21°C, 49.99 min, and 0.44%. The highest hunter’s L (lightness), a (redness), and b- (yellowness) values were 47.39 (pH 4.86, 50.72°C, 51.60 min, and 0.44%), −1.34 (pH 5.48, 49.36°C, 46.29 min, and 0.21%), and 13.18 (pH 5.49, 50.05°C, 43.31 min, and 0.23%), respectively. The highest electron donating activity was 68.36% at pH 4.51, 50.62°C, 47.00 min, and 0.23%. The highest limonin and nomilin contents were 3.49 mg/100 g (pH 4.51, 50.30°C, 48.34 min, and 0.21%) and 1.56 mg/100 g (pH 4.59, 50.08°C, 66.07 min, and 0.30%).  相似文献   

11.
Effects of heating time and temperature, pH, and soluble solid levels on serum viscosity and serum color of tomato juice were studied. The samples were canned in 18 mL TDT cans and exposed to processing temperatures of 88C, 102C, and 112C for 30, 60, and 120 min. Depending upon the time and temperature of heating, and initial viscosity of the serum, the losses in viscosity ranged from 3.0–55.6% being higher in serum with higher initial viscosity. Percent losses in serum viscosity during heating of juice increased (6–60%) with increase in pH (3.8–4.9) and soluble solids (6°–24°) in the juice. An increase in pH and soluble solids also enhanced heat induced browning in the serum with values varying from 0.1–2.69.  相似文献   

12.
目的:制备球形多孔硅酸镁,并用于糖汁脱色研究。方法:结合水热合成法和模板法,以氯化镁和硅胶球为前驱体制备多孔硅酸镁,并对其进行XRD、FTIR和SEM表征分析;然后以制备的硅酸镁为吸附剂,以脱色率为指标,考察了球形多孔硅酸镁用量、吸附温度、吸附时间及pH对甘蔗原糖溶液脱色性能的影响;最后考察了多孔硅酸镁对糖汁色素的吸附过程。结果:表征分析可知制备的多孔硅酸镁为球形多孔硅酸镁。糖汁脱色实验结果表明,在球形多孔硅酸镁用量为0.10 g、吸附温度为30℃、吸附时间为40 min、pH为6.0时,其对糖汁的脱色率为69.8%。经拟合得知,球形多孔硅酸镁对糖汁色素的吸附过程符合准二级动力学吸附方程与Langmuir等温吸附方程。结论:本研究可为发展镁法制糖技术及工艺提供新的方法与理论依据。  相似文献   

13.
制糖脱色成本占糖浆精制成本的1/3,而酶促褐变是蔗汁颜色加深的一个主要原因。本文探讨了制糖压榨过程中褐变对蔗汁颜色变化的影响,进一步研究了亚硫酸盐对蔗汁酶促褐变的抑制。结果表明:褐变对蔗汁色值贡献率大于50%,前10 min褐变速度最快;蔗梢蔗汁相对于成熟蔗茎蔗汁酶促褐变程度高;压榨后立即预灰能减少酶促褐变色素生成;多酚氧化酶活性在蔗汁预灰pH大于9.5时为0,在pH6.0~6.5最高;3 mmol/L NaHSO3的添加量能完全抑制蔗汁酶促反应发生。研究可为甘蔗制糖工艺的改进提供依据。  相似文献   

14.
Streptomyces sp. AOA40, which produces halotolerant and thermotolerant xylanase, was isolated from Mersin soil. Various carbon sources were tested for xylanase production with selected fermentation medium. The best carbon source was selected as corn stover. The effect of corn stover concentration and particle size, composition of fermentation medium, fermentation condition such as initial pH and agitation rate on xylanase production was determined. After production, xylanase was partially purified with ion-exchange chromatography and gel filtration chromatography for characterization of xylanase and application in fruit juice and dough improvement. The optimum pH for the activity of xylanase occurred at pH 6.0 in phosphate buffer, while the optimum temperature was 60°C. The relative xylanase activity in the pH ranges of 4–9 remained between 59.93 and 54.43% of the activity at pH 6.0 (100.00%). The xylanase activity showed a half-life of 172 min at 70°C, which was reduced to 75 min at 80°C. The enzyme was highly inhibited by 10–100 mM of Hg+2, EDTA, Mg+2, SDS and 100 mM Cu+2. Clarity of fruit juices increased after enzymatic treatment of apple (17.85%), grape (17.19%) and orange juice (18.36%) with partially purified xylanase and also reducing sugar concentrations of these fruit juices were improved by 17.21, 16.79 and 19.57%, respectively. Also, dough volume was raised 17.06% with using partially purified Streptomyces sp. AOA40 xylanase in bread making.  相似文献   

15.
过氧化物酶在蔗汁澄清工艺中除酚脱色的研究   总被引:1,自引:0,他引:1  
本文研究了pH值、温度、H2O2用量及辣根过氧化物酶(HRP)用量等因素对辣根过氧化物酶催化H2O2氧化多元酚类的影响,并分别用HRP处理亚硫酸法糖厂的混合汁、清汁、糖浆,考察其对糖汁的除酚脱色效果。试验结果表明,HRP催化H2O2氧化处理糖汁具有明显的除酚脱色作用。  相似文献   

16.
利用维生素C改性碱性钙基膨润土制备了一种含有多羟基化合物的维生素C膨润土。通过单因素实验,分析了反应温度、时间、维生素C用量、分散剂浓度等因素对材料有机物含量的影响,获得最佳条件为:采用99.7%乙醇为分散剂加到维生素C加入量为80%的碱性土中,60℃下反应3h,维生素C膨润土的有机物含量达38.94%。结构表征说明该材料仍保持碱性钙基膨润土的层状结构和层间距,表面粗糙多孔,热稳定性好。将该材料与过氧化氢协同应用于甘蔗汁澄清脱色中,当40mL的蔗汁经碱性土调节pH后,依次添加2mL过氧化氢和0.3g维生素C膨润土,在50℃反应30min,脱色率可达62.98%。  相似文献   

17.
Enzymatic treatment for juice extraction is most commonly used now a days. The enzymatic process is claimed to offer a number of advantages over mechanical-thermal comminution of several fruit pulps. Enzymes are an integral component of modern fruit juice manufacturing and are highly suitable for optimizing processes. Their main purposes are: increase extraction of juice from raw material, increase processing efficiency (pressing, solid settling or removal), and generate a final product that is clear and visually attractive. Juice extraction can be done by using various mechanical processes, which may be achieved through diffusion extraction, decanter centrifuge, screw type juice extractor, fruit pulper and by different types of presses. Enzymatic treatment prior to mechanical extraction significantly improves juice recovery compared to any other extraction process. Enzymatic hydrolysis of the cell walls increases the extraction yield, reducing sugars, soluble dry matter content and galacturonic acid content and titrable acidity of the products. Enzymatic degradation of the biomaterial depends upon the type of enzyme, incubation time, incubation temperature, enzyme concentration, agitation, pH and use of different enzyme combinations. We can conclude from the technical literature that use of the enzymes i.e. cellulases, pectinases, amylases and combination of these enzymes can give better juice yield with superior quality of the fruit juice. Pectinase enzyme can give maximum juice yield i.e. 92.4% at 360 minutes incubation time, 37°C incubation temperature and 5 mg/100 g of enzyme concentration. Whereas the combination of two enzymes i.e. pectin methyl esterase (PME) and polygalacturonase (PG) at 120 minutes of incubation time, 50°C of incubation temperature and 0.05 mg/100 gm of enzymatic concentration can give the maximum yield of 96.8% for plum fruits. This paper discusses the use of enzymes in fruit juice production focusing on the juice recovery, clarity and effect of the particular enzyme on the biochemical properties of the fruit juices.  相似文献   

18.
Thermal conductivity, thermal diffusivity, and density of yellow mombin juice were determined at 8.8–49.4 °Brix and at temperature from 0.4 to 77.1 °C. Apparent viscosity was also measured between 7.8 and 30 °Brix and at temperature from 0 to 60 °C. Yellow mombin juice was produced from fruits of two different batches and the concentration process was performed using a roto evaporator or a rising film evaporator, single effect, with recirculation, under vacuum, to obtain concentrated juice. In order to obtain different concentrations, concentrated juice was diluted with distilled water. Multiple regression analysis was performed to fit thermal conductivity, thermal diffusivity and density experimental data obtaining a good fit. Arrhenius and power law relationships were proposed to fit apparent viscosity as a function of temperature and juice concentration at typical shear rates found during processing. The rheological parameters together with experimental values of pressure loss in tube flow were used to calculate friction factors, which were compared to those resulting from theoretical equation.  相似文献   

19.
猕猴桃酒中高级醇的研究   总被引:3,自引:1,他引:2  
研究了猕猴桃酒酿造过程中工艺条件对高级醇的影响 ,结果表明加大酵母接种量、分批加糖、低温发酵、低 pH值、高澄清度、及时分离酵母泥都能使酒中的高级醇减少。其中以发酵温度和果汁澄清度的影响最大 ,低温发酵 (16℃ )或澄清度很高的果汁 (滤纸过滤 )发酵时 ,要比较高温度 (2 8℃ )发酵、未经任何处理的果汁发酵产生的高级醇低 5 0 %以上。  相似文献   

20.
本文提出了一种低硫低磷甘蔗制糖澄清新工艺,该工艺过程使用聚二甲基二烯丙基氯化铵、重硫氧、聚磷硅酸锌对甘蔗混合汁进行澄清脱色。讨论了不同工艺条件对甘蔗混合汁重力纯度差、脱色率和除浊率的影响。通过人工神经网络敏感性分析,获得新工艺优化条件为:预灰pH 6.3±0.1;聚二甲基二烯丙基氯化铵用量7 mL/L(配制浓度2%);重硫氧用量1.1 g/L;聚磷硅酸锌用量3.0 mL/L(配制浓度10%);聚丙烯酰胺用量2.5 mg/L;中和pH 8.3;一次加热温度65±5℃;二次加热温度100±2℃。结果表明,低硫低磷甘蔗制糖澄清新工艺优于传统制糖工艺。  相似文献   

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