【作者】 全海慧；

【导师】 李诚；

【作者基本信息】 四川农业大学 ， 食品科学， 2011， 硕士

【摘要】 铁是人体必不可少的营养元素,有着重要的生理作用,然而铁的缺乏是全球主要营养性疾病,食物铁强化被誉为预防铁缺乏最有效的方法之一。本试验采用营养丰富、消费潜力大的牛乳为强化载体,以共沉淀氢氧化铁作为强化铁源,旨在研制一种新型铁强化牛乳。主要研究了：共沉淀氢氧化铁的添加量对牛乳品质的影响；同一添加量下,不同铁源对牛乳品质的影响；共沉淀氢氧化铁强化乳的超声均质条件；稳定剂的选择及复配。主要研究结果如下：1.实验以日需铁最大量的妊娠后期人群需铁量(35 mg/d)的2/3为上限,以每人每日饮用牛乳250 g计算,分别按每100 g牛乳添加共沉淀氢氧化铁3.3 mg、4.3 mg、5.3 mg、6.3 mg、7.3 mg、8.3 mg、9.3 mg(以Fe计),制得杀菌牛乳,比较共沉淀氢氧化铁的不同添加量对牛乳感官品质的影响及在4℃贮藏过程中理化指标(pH、TBA)的变化；贮藏8d后,测定样品液中铁含量。结果表明：铁添加量在5.3mg/100 g及其以下的样品感官品质较好；添加共沉淀氢氧化铁的样品pH增大,且铁添加量越多,pH增加越多；在贮藏期间,各样品pH变化不大,TBA值呈上升趋势,不同铁添加量的样品TBA值差异不显著；贮藏8d后,铁添加量≤5.3 mg/100 g的样品液中铁含量达添加量的89%。说明以共沉淀氢氧化铁作为牛乳铁强化剂可行。2.在同一铁添加量下,以焦磷酸铁、共沉淀氢氧化铁、硫酸亚铁、乙二胺四乙酸铁钠(NaFeEDTA)作为铁源对杀菌牛进行铁强化,比较了四种铁源对牛乳感官品质的影响,测定样品液中铁含量及在4℃贮藏过程中理化指标(pH、TBA)的变化。结果表明：NaFeEDTA铁强化乳感官品质最好,共沉淀氢氧化铁强化乳稍次之,焦磷酸铁及硫酸亚铁样品的最差；不同铁源的强化乳中测得铁含量为共沉淀氢氧化铁>NaFeEDTA>硫酸亚铁>焦磷酸铁；添加硫酸亚铁、NaFeEDTA使牛乳pH降低；共沉淀氢氧化铁对牛乳的脂肪氧化作用小于硫酸亚铁及NaFeEDTA。共沉淀氢氧化铁可以作为牛乳铁强化的较佳铁源。3.采用超声波对共沉淀氢氧化铁强化乳进行均质处理,以180 w、270 w、360 w三种超声功率,分别在20 s、65 s、110 s、155 s、200 s、245 s、290 s、335 s的超声时间下处理牛乳,测定样品吸光值,贮藏8d后,测定沉淀量及样品液中铁含量。结果表明：超声功率为180 w,270 w,360 w时,超声时间分别在245 s,200 s,155 s时,共沉淀氢氧化铁强化乳分散最均匀；功率为180 w,270 w,360 w时,超声时间分别在245s,245s,200s时,共沉淀氢氧化铁强化乳沉淀量最少,分别为0.467%,0.433%,0.444%。综合成本因素,选择超声均质的最佳条件为：功率180 w,超声时间200s～245s。4.通过对乳化剂(单甘酯、蔗糖酯、司盘60、吐温60)、增稠剂(卡拉胶、微晶纤维素(MCC)、瓜尔豆胶、黄原胶、羧甲基纤维素钠)及添加盐(三聚磷酸钠、六偏磷酸钠、焦磷酸钠、柠檬酸钠)的单因素试验,选取对共沉淀氢氧化铁强化乳稳定性影响明显的因素,采用混料设计进行稳定剂复配。结果表明：添加盐对共沉淀氢氧化铁强化乳稳定效果不明显；选用卡拉胶、维晶纤维素、复合乳化剂(单甘酯：蔗糖酯为7：3)进行复配,得到共沉淀氢氧化铁强化乳稳定剂最佳配方比例：卡拉胶：微晶纤维素：复合乳化剂为0.4000：0.2040：0.3996。5.根据最佳稳定剂配方,采用180 w,200 s的超声均质条件,制得样品,于4℃下贮藏,观察贮藏过程中组织状态变化；于样品制得Od、3d、6d、9d、12 d、15 d测定pH、TBA及细菌菌落总数变化。结果表明：12d内无脂肪上浮,9d内无明显铁沉淀；贮藏15d中pH和TBA变化不明显；共沉淀氢氧化铁强化乳贮藏15d中,细菌菌落总数最高时达240 CFU/mL,远小于国家标准中巴氏杀菌牛乳的微生物指标。综合上述结果,共沉淀氢氧化铁的添加量为4.5 mg/100 g牛乳(以Fe计)时,加入0.15%的复合稳定剂(卡拉胶：微晶纤维素：复合乳化剂为0.4000：0.2040：0.3996),采用180 w,200 s的超声均质条件,在95℃下,杀菌5 min,制得的共沉淀氢氧化铁强化牛乳,于4℃下贮藏,9d内组织状态未发生变化且微生物含量低。更多还原

【Abstract】 Iron is an essential nutrient for human body with important physiological role, however, iron deficiency is the main nutritional disease in the world, and iron fortification of foods was identified as one of the most effective strategies for the contral of iron deficiency. In this experiment, milk was used as strengthening carrier that have characteristics of Nutrient-rich and great potential consumption, and the co-precipitation ferric hydroxide acted as a iron source of fortification, the aim was to develop a new type of iron fortified milk. It mainly studied:The effects of co-precipitation ferric hydroxide supplementation on the quality of milk; The effects of different iron sources on the quality of milk under the same dosage; The homogeneity condition for strengthening milk of co-precipitation ferric hydroxide; The selection of stabilizers and their combination. The main research results are as follows:1. The experiment regarded the 2/3 of the maximum iron requirements (35 mg/d) of the people during late pregnancy as the upper limit, and the consumption of milk was calculated as 250 g per person per day, then the milks were fortified with different amounts of co-precipitation ferric hydroxide (3.3 mg,4.3 mg,5.3 mg,6.3 mg,7.3 mg,8.3 mg,9.3 mg, in Fe) per 100 g and prepared to the sterilization milk. Through compared the effects of different adding amounts of co-precipitation ferric hydroxide on the sensory quality of milk, the changes of physiochemical indexes (pH value and TBA value) during the storage at 4℃, and determined the iron content of the samples, after the storage of 8 days. The results indicated that:the sensory qualities of sample was the better with the added amount of 5.3 mg/100 g or below it; when co-precipitation ferric hydroxide was added, all samples’pH value increased, and the more amount of iron was added, the higher pH rose; during the storage period, the variations of pH value were very small, the TBA value showed a rising tendency, and the difference of the TBA values among different samples that were added to in different amounts of iron was not significant; after the storage of 8 days, the iron content of sample milk liquid reached the point of 89%of the added amount, when the adding amount was controlled under 5.3 mg/100 g. Co-precipitation ferric hydroxide could be used as an iron fortificant for milk.2. Under the same iron dosage, ferric pyrophosphate, co-precipitation ferric hydroxide, ferrous sulfate, sodium iron EDTA (NaFeEDTA) were used as iron sources for iron fortification of sterilization milk, their effects on sensory quality of milk were compared, the iron contents of the samples and the changes of physiochemical indexes (pH value and TBA value) were inspected during the storage at 4℃. The results indicated that:sensory quality of milk fortified with NaFeEDTA was the best, was slightly higher than that of the co-precipitation ferric hydroxide, and that of ferrous sulfate and ferric pyrophosphate were the worst; The iron content of samples which were added different iron sources was measured as co-precipitation ferric hydroxide>NaFeEDTA>ferrous sulfate>ferric pyrophosphate; The pH value of milks fortified with ferrous sulfate and ferric pyrophosphate decreased; The samples’ TBA value were added the co-precipitation ferric hydroxide into were smaller than samples’ of ferrous sulfate and Ferric pyrophosphate. It proved that the co-precipitation ferric hydroxide was a better source of iron as an iron fortificant for milk.3. Homogenisation of milk fortified with co-precipitation ferric hydroxide was carried out by power ultrasound, the parameters of that included ultrasonic power level (180 w,270 w,360 w) and treatment times (20 s,65 s,110 s,155 s,200 s,245 s,290 s,335 s). The absorbance of samples were determined; The amount of precipitation and iron content in sample solution were inspected, after the storage of 8 days. The results showed that:when the ultrasonic power was at 180 w,270 w,360 w, strengthening milk was the most evenly distributed at the ultrasonic time 245 s,200 s,155 s respectively; when the ultrasonic power was at 180 w,270 w,360 w and the ultrasonic time was at 245 s,245 s,200 s, strengthening milk had the least precipitation amount of 0.467%,0.433%,0.444% respectively. Considering the cost factors, the best choice of ultrasonic conditions was 180 w,200 s-245 s.4. By the single factor experiment of emulsifier (monoglyceride, sucrose ester, Span 60, Tween 60), thickener (carrageenan, microcrystalline cellulose (MCC), guar gum, xanthan gum, carboxymethyl fiber Sodium) and addition salt (sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, sodium citrate), chose the factors which had a obvious affection to the stability of strengthening milk of coprecipitation ferric hydroxide and based on the mixture design method for compound stabilizer. The result showed that addition salt did not have a obvious affection to milk fortifitied with co-precipitation ferric hydroxide; selected carrageenan, MCC and composite emulsifier (monoglyceride:sucrose ester 7:3) as compound stabilizer, got the radio of the optimal stabilizer for the milk: carrageenan:microcrystalline cellulose:emulsifier was 0.4000:0.2040:0.3996.5. The sample was prepared by the optimal composite stabilizer, under the ultrasonic conditions at 180w,200s, then stored at 4℃, observed the change of the tissue state during the time of storage process, and tested the changes of pH value, TBA value, and the total number of bacteria on the day,0 d,3 d,6 d,9 d,12d,15 d. The result showed that:there was no fat floating during 12 days, and obvious iron deposits observed in the samples at 9 days of the storage; the changes in pH value and TBA value were not obvious during 15 days; during the storage of 15 days of the strengthening milk, the highest total number of bacteria reached 240 CFU/mL, far less than the microbiological indexes of pasteurized milk in national standards.In conclusion, the iron fortification of milk, which co-precipitation ferric hydroxid and composite stabilizer (carrageenan:microcrystalline cellulose:emulsifier was 0.4000:0.2040: 0.3996)was added into at 4.5 mg (in Fe),0.15 g per 100 g respectively and was homogenezed under ultrasonic condition of 180 w,200 s and sterilizated 5 min at 95℃, had no change in the organizational state and less content of the microbial during 9 d stored at 4℃.更多还原