Development On Iron Fortification Of Milk With Co-precipitation Ferric Hydroxide

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℃.