【作者】 朱燕；

【导师】 曾新安； 李巍青；

【作者基本信息】 华南理工大学 ， 轻工技术与工程， 2011， 硕士

【摘要】 以广东梅县沙田柚为原料,采用先进的现代果汁加工技术,针对沙田柚果汁在加工过程中出汁率低下和苦味严重两大工程难题进行研究,并进行了年加工量2500 t的鲜柚生产车间设计。1.利用果胶酶处理沙田柚果浆,考察酶解温度、酶解时间及酶添加量对果浆出汁率的影响,优化沙田柚果浆酶解工艺条件。结果表明:最佳酶解条件为酶解温度40-45℃,酶解时间3 h,酶添加量75-100 mg/L,此时出汁率在80%以上;比较酶解前后果汁的主要理化指标的变化,果汁可溶性固形物提高了0.6°Brix,还原糖含量由9.4 g/L提高到10.3 g/L,出汁率提高了18.2%,果汁黏度由30 mPa·s显著下降至2 mPa·s,V_C损失率为28.2%,同时果汁透光率也显著提高,而对果汁总酸、pH值等基本无影响。2.通过感官评定,定性研究了柚汁苦味随时间、温度和pH变化的规律;同时比较了不同方法对柚汁的脱苦效果。研究结果表明:柚汁苦味随时间的延长而增加,高温对苦味转化具有促进作用,pH值的变化对柚汁色泽有一定的影响;活性炭和树脂LX-900吸附对柚汁脱苦综合评分较高,树脂D101有一定的脱苦作用,而β-环状糊精包埋法、PVPP吸附法、柚苷酶酶解法和超滤脱苦效果不明显。3.分别比较了D101、AB-8、DM130、D4020、LX-900、ZGA451FD六种树脂对柚汁中苦味物质柚皮苷的静态吸附解析性能;选取D101树脂确定其动态吸附解析工艺条件,研究了其再生稳定性,并比较了树脂吸附前后果汁主要指标的变化。树脂静态吸附解析实验结果表明,柚皮苷属于二氢查耳酮类,含有较多的酚羟基,易被非极性或者弱极性的大孔吸附树脂吸附从而达到果汁脱苦的目的;D101型树脂动态吸附解析实验研究了高径比、上液流速、上液pH以及解析液浓度、解析流速对果汁中柚皮苷的吸附解析性能,结果表明:当柚汁调至pH3.5时,以14 mL/min流速通过高径比为6∶1的树脂柱(Φ25),将柚汁中柚皮苷浓度降至300.0 mg/L时,树脂的处理能力为62 BV,吸附量高达53.8 mg/mL,用9 BV 50%(V/V)乙醇溶液以10 mL/min流速通过树脂柱,洗脱完全;再生稳定性试验表明,树脂吸附抗机械强度性好,吸附性能稳定,再生容易,使用周期长,适合工业化生产;果汁主要指标的测定结果表明:D101树脂吸附能够有效解决果汁苦味严重的问题,而对果汁其他成分基本无影响。4.进行了年加工量鲜柚2500 t的工厂设计。本设计过程中进行了详细的工艺论证,并在此基础上进行了物料衡算、设备选型、对水、电、汽消耗量进行估算以及人员安排,最后进行了投资估算和成本核算。结果表明该项目总投资为2319万元,年利润额为968万元,估计资金回收期约为2.4年。更多还原

【Abstract】 Using Shatian pomelo from Mei county in Guangdong as materials, the low juice yield and fierce bitter taste during the juice processing were investigated with the advanced modern juice processing technology; and a workshop with annual processing capacity of 2500 t shatian polemo was designed.1. The enzymolysis conditions (temperature, time and the amount of pectinase) were discussed. The results showed that the juice yield rate could reach up to 80% at least by the optimum conditions: temperature, 40-45℃; time, 3 h; amount of pectinase, 75-100 mg/L. After enzymolysis processing, the soluble solids concentration (SSC) of the berry increased by 0.6°Brix, the juice yield increased by 18.2% and the reduction sugar content increased from 9.4 g/L to 10.3 g/L; the viscosity had a significant reduction from 30 mPa·s to 2 mPa·s; the loss rate of V_C was 28.2% and the transparency was greatly improved; however, the juice total acid (TA) and pH changed a bit.2. The variation of bitter taste in the pomelo juice with time, temperature and pH was qualitatively studied by sensory evaluation; and the debittering effects of different methods were also compared. The results showed that bitter taste in pomelo juice increased with time, temperature had a role in promoting transformation of bitterness, and pH led to the color changes. The adsorption of active carbon and LX-900 resins got higher sensory scores, D101 resins play a part role on the decrease of bitter taste but the debittering effects ofβ-cyclodextrin embedding, PVPP adsorption, the enzymatic of nariginase, and ultrafiltration were not obvious.3. Static adsorption and elution performance of resins (D101 resin、AB-8 resin、DM130 resin、D4020 resin、LX-900 resin、ZGA451FD resin) on narigin (the bitterness) in pomelo juice were studied; then D101 resin was chosen to study the dynamic adsorption and elution technological conditions and regeneration stability; finally, the changes in typical properties of pomelo juice before and after D101 resin adsorption were compared. The result of static test showed that narigin, a dihydrochalcone, was easily adsorbed by macroporous absorption resin with non-polar or weak polar and thus the juice was debitterized. In the dynamic test, the effects the height/diameter ratio of D101 resin column, feed flow velocity, pH value of pomelo juice on the adorption of narigin and the effects of the eluent concertration and flow velocity on narigin recovery were studied. The results showed that when the narigin concertration in polemo juice was reduced to 300.0 mg/L, the processing capacity of resin column was about 62BV and the adorption could reach up to 53.8 mg/mL with the condition (height/diameter ratio of D101 resin column (Φ25), 6∶1; feed flow velocity, 14mL/min; pH value of pomelo juice, 3.5). After 9 BV 50% (v/v) ethanol solution passed through the resin column, the column was recovered. In the regeneration stability test, D101 resins had good mechanical resistance, stable adsorption properties, long life cycle and was easily renewable, which was greatly suitable for industrial production. The results of changes in typic properties of pomelo juice showed that D101 resin adsorption can resolve the problem of fierce bitter taste and had little impact on other ingredients.4. A workshop with annual processing capacity of 2500 t Shatian polemo was designed. During the design, a detailed demonstration of process was conducted; after that, material balance, equipment selection, estimation of water, electricity and gas consumption, staffing, the final estimate of the investment and cost were done. The results showed that the total investment of this project is about 23.19 million, annual profit is 9.68 million, and the estimated payback period is approximately 2.4 years.更多还原