Direct gas-fired heating of a pilot-scale spray drier using natural gas for milk powder manufacture

A pilot-scale spray drier was converted to direct gas-fired heating using natural gas to determine its effects on the chemical and physical properties of the skimmed milk powders dried by this technique. There were no significant differences in acidity, bulk density, solubility index and moisture content compared with the control samples ('indirect' heating of drier) during the course of 11 trials. The heated drying air (200°C) was analysed for the presence of NO + NO₂, CO and CO₂, and some increases at ppm levels in the nitrate (NO₃-) and nitrite (NO₂-) content of the milk powders were observed. Colour and flavour characteristics of the samples were not affected.     

Direct 'low-NOX' gas combustion heating of a spray drier during milk powder manufacture

Direct gas-fired heating experiments were carried out during spray drying of milk using a 'low-NO_x' burner in order to minimize contamination of the drying air by the combustion products in the flue gases from the burner. The burner, model CXA (Urquhart Engineering Co Ltd, England) was of the 'excess air' type, and was fuelled by natural gas. There was no significant difference between the mean values of the nitrate content of the skim milk powders produced by direct firing, electrical heating and the factory produced (indirect heating) sample. Only with nitrite content (NO₂) was there a significant difference between the direct gas fired (0.811 ppm NO₂-) and the factory (0.460) samples, but the range of values encountered was very small (0.24–1.68). Direct gas-fired heating using the low NO_x burner did not contribute to the levels of N-nitrosodimethylamine (NDMA) detected in the test powders when compared to the levels found in the control samples (trace-1.3 μg/kg NDMA).     

纯乳成分全脂速溶乳粉及其制备方法

采用乳成分制品制备喷涂物料,生产分散度８５％以上的全脂乳粉,称之为“纯乳成分全脂速溶乳粉”;其制备方法又可适用于各种配制乳粉,强化乳粉,豆乳粉及其他速溶饮品,配套设备“三分流组合式离心喷雾器”,可在乳粉喷雾干燥过程中,塔内直接进行颗粒附聚和喷涂,起到与流化床相同作用。     

热风干燥与真空冷冻干燥对桑葚果粉品质的影响比较

以桑葚为试材,比较了热风干燥和真空冷冻干燥对桑葚果粉品质的影响。结果表明:真空冷冻干燥桑葚果粉得率和含水率低于热风干燥果粉,但溶解性能优于后者,电镜下观察到真空冷冻干燥果粉颗粒大,颗粒间孔隙较多结构疏松,热风干燥果粉颗粒间聚集紧密孔隙较少,真空冷冻干燥果粉Vc、总酚、花色苷的保留率分别为97.97%、98.40%和96.36%,而热风干燥桑葚果粉Vc、总酚、花色苷等物质保留率分别为37.47%、92.07%和69.13%,损失比较严重,真空冷冻干燥可较完好地保持桑葚原有品质。     

奶粉干燥过程的控制系统设计

对传统的干燥控制方法进行了评述，对奶粉干燥系统的控制方案进行了分析比较，并在对喷雾干燥过程中物料与热量衡算及粒子运动轨迹计算的基础上对奶粉喷雾干燥过程的控制系统进行了设计，为提高干燥奶粉的品质奠定了基础。     

Physical properties of goat milk powder with soy lecithin added before spray drying

In this study, physical characteristics of goat milk powder produced with the addition of soy lecithin at levels of 0 (control), 0.4, 0.8 and 1.0 g lecithin/100 g of total solids in concentrated milk before the spray drying process were investigated. Goat milk was pasteurised, concentrated at 40% of total solids, spray dried and packed in plastic bags under vaccum conditions. Lecithin addition decreased the wetting time of milk powders, although no influence was observed on dispersibility, water sorption, water activity and particle size distribution of the powders. Powders with higher levels of lecithin showed significantly lower brightness, with a greater intensity of yellow colour. It was concluded that lecithin addition before spray drying process at the minimal proportion in concentrated milk of 0.4 g lecithin/100 g of total solids in concentrated milk is useful for achieving more rapid wetting time of goat milk powder.     

巴旦杏乳固体饮料喷雾干燥工艺研究

以巴旦杏和牛乳为原料,通过添加护色剂、助干剂、稳定剂、甜味剂、酸味剂、乳化剂,利用喷雾干燥技术,经正交试验设计出最佳的复合双蛋白乳固体饮料.试验结果表明,最佳辅料配方为:麦芽糊精30％、β-环状糊精2％、白砂糖10％、柠檬酸0.15％、CMC-Na 0.25％、单甘酯0.15％、蔗糖酯0.4％;最佳喷雾干燥参数为:进料浓度20％、进料温度45℃、风机频率50r/min、温度220℃.在此条件下进行喷雾干燥所得巴旦杏乳固体饮料溶解速度快,酸甜可口,柔滑细腻.     

DHA微胶囊配方乳粉的喷雾干燥工艺优化研究

采用单因素实验,研究了均质压力、进料流量、进风温度对二十二碳六烯酸(DHA)微胶囊配方乳粉品质的影响,并进一步对工艺参数进行响应面优化。结果表明:均质压力、进料流量、进风温度对DHA保留率均有极显著影响(p<0.01);响应面优化得到DHA微胶囊在配方乳粉中应用的最佳工艺条件为:均质压力36～37MPa、进料流量20.50mL/min、进风温度165℃,DHA保留率可达95.28%±0.54%。      

DHA微胶囊配方乳粉的喷雾干燥工艺优化研究

采用单因素实验,研究了均质压力、进料流量、进风温度对二十二碳六烯酸(DHA)微胶囊配方乳粉品质的影响,并进一步对工艺参数进行响应面优化.结果表明:均质压力、进料流量、进风温度对DHA保留率均有极显著影响(p＜0.01);响应面优化得到DHA微胶囊在配方乳粉中应用的最佳工艺条件为:均质压力36 ～ 37 MPa、进料流量20.50mL/min、进风温度165℃,DHA保留率可达95.28％±0.54％.     

花生蛋白奶粉的干法生产工艺研究

以去壳花生仁为原料,经低温烘烤、脱红衣、冷榨脱脂、超微粉碎等工艺生产出花生蛋白粉,将其与全脂奶粉混合生产花生蛋白奶粉,所得产品溶解度高、冲调性好、口感细腻、营养均衡,同时具有奶味和花生特有的香味。     

气相色谱法测定婴幼儿配方奶粉和母乳中的碘

目的建立气相色谱法测定婴幼儿配方奶粉和母乳中碘的方法。方法在GB 5413.23-2010食品安全国家标准《婴幼儿食品和乳品中碘的测定》的基础上,对碘的气相色谱(gas chromatography,GC)检测方法进行改进,应用改进后的方法对62种婴幼儿配方奶粉和124份母乳样品进行检测。结果碘在1.00~2000.00μg/L范围内线性关系良好,线性相关系数(r~2)为0.9999;检出限、定量限分别为0.30、1.00μg/L;利用不同品牌婴幼儿配方奶粉中碘检测结果的相对标准偏差(relative standard deviation,RSD)考察方法精密度,相对标准偏差值在1.39%~1.61%之间;在5、25、100μg/100 g的加标浓度下,回收率在97.46%~98.98%之间,对应的RSD值在2.52%~2.73%之间。婴幼儿配方奶粉中的碘含量在33.14~132.94μg/100 g之间,母乳样品中的碘含量在31.25~1690.00μg/L之间。结论本方法减少了样品和试剂的使用量,节约了实验成本,简化了实验步骤,提高了检测效率,对于碘的准确测定、保障婴幼儿的健康成长具有重要意义。     

Effects of pretreatment and air drying temperature on Noni fruit powder

Food Science and Biotechnology - The plant Morinda citrifolia L. (Noni) has been the subject of several recent research due to its positive impact on the treatment and prevention of a variety of...     

利用热风喷雾干燥方法生产纯天然柑橘(橙)果粉

将柑橘（橙）全果皮肉分离，果皮经热烫、水漂及果胶酶适度处理后，与去籽的果肉以1：1.4～1：1．6的比例混合，利用热风喷雾干燥方法可获得干燥、疏松的纯天然柑橘（橙）果粉。     

苹果渣过热蒸汽-热风联合干燥及干粉品质分析

果渣传统干燥存在干燥时间长、能耗大、果渣褐变严重等问题。尝试采用联合干燥方法对苹果渣进行脱水:前段(果渣含水率81%~63%)采用过热蒸汽干燥,后段(果渣含水率63%~7%)采用热风干燥。为了研究苹果渣过热蒸汽干燥特性,选取蒸汽温度和流速为试验因素,设计了2因素4水平全面正交试验;苹果渣热风干燥条件固定:70℃、1.5 m/s。结果表明,苹果渣过热蒸汽干燥存在预热冷凝和恒速干燥段;苹果渣过热蒸汽干燥速率随蒸汽温度上升而加快,蒸汽流速对干燥速率的影响不显著;经过热蒸汽干燥后,苹果渣热风干燥时间显著减少;联合干燥所得苹果渣干粉色度值a和b较小,颜色较浅,苹果渣干粉持水力和吸油力范围分别为4.82~7.77和0.83~1.32,平均果胶提取得率9.3%;与单一热风干燥相比,采用过热蒸汽联合热风干燥苹果渣可大大减少干燥时间,且干燥所得苹果渣干粉褐变得到了较好地抑制,果胶提取率较高。     

气相色谱法测定液体乳及乳粉中的7种防腐剂

应用气相色谱技术建立液体乳及乳粉中山梨酸、苯甲酸、脱氢乙酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯和对羟基苯甲酸丁酯共7种防腐剂的定量分析方法.样品酸化后用乙酸乙酯提取,提取液经脱水后直接进样,中等极性毛细色谱柱DB-17分离,氢火焰离子化检测器检测.结果表明,7种防腐剂在质量浓度为10～500mg/L范围内呈良好的线性关系,相关系数在0.999以上,方法的检出限(以信噪比大于3计)为0.2～0.5 mg/L,定量限(以信噪比大于10计)为0.7～1.7 mg/L,平均加标回收率为96.6％～104.3％,RSD＜5％.该方法前处理简单快速、检测效率高、线性范围宽、灵敏度高、实用性较强.     

喷雾干燥法制备低嘌呤豆浆速溶粉工艺研究

以盐析法制备的低嘌呤豆浆为原材料,在单因素试验的基础上,通过L9(34)正交试验设计优化喷雾干燥工艺条件,制得低嘌呤豆浆速溶粉,并对其进行品质评价。结果表明,最佳喷雾干燥条件为进口温度185℃,进料流量16 m L/min,固形物含量为10%,平均干粉得率为66.13%;低嘌呤豆浆速溶粉平均总嘌呤含量为100.34 mg/100 g,总嘌呤含量降低了48.80%;感官指标、理化指标和微生物指标均符合相关标准要求。     

热风干燥温度对甘薯粉品质的影响

为探究热风干燥温度对甘薯粉品质的影响,比较不同干燥温度对甘薯粉色泽、复水性、粒径、黏度、堆积密度、还原糖和淀粉含量等品质指标的影响。结果表明:热风干燥温度对甘薯粉的复水性、粒径、黏度和淀粉含量有显著影响(P0.05);随着干燥温度升高,失水速率增加,干燥时间缩短,淀粉含量增加,干燥温度为80℃时,甘薯粉的粒径最小,复水性最好,呈现出较好的色泽。     

喷雾干燥法制备乳脂微胶囊及其特性研究

运用响应面分析法,优化乳脂微胶囊喷雾干燥法制备工艺参数,并对其基本理化指标、形态特征及其抗潮性、热稳定性、氧化稳定性和贮藏稳定性进行测定分析。结果表明：喷雾干燥法制备微胶囊的最佳工艺参数为：进风温度178℃、出风温度80℃、均质压力43MPa,其微胶囊乳脂包埋率为93.14%、水分含量3.12%、灰分2.07%、蛋白质18.56%、溶解度67.01g/100g、密度0.45g/cm₃,粒径分布在4～90μm。产品具有抗氧化稳定性好,易吸水、不耐高温的贮藏特性。加工应用适宜温度在220℃以下。     

红薯叶粉热泵-热风联合干燥工艺优化

为保证红薯叶粉品质,降低加工能耗,采用热泵-热风联合干燥技术对红薯叶进行处理,在单因素试验基础上运用Box-Behnken Design优化试验,研究热泵干燥温度、热风干燥温度和转换点含水率对单位能耗、叶绿素含量、色泽L*值和吸湿性的影响,通过加权综合评分法推导多项式回归模型,进而优化联合干燥工艺参数。经响应面优化的干燥参数为:热泵干燥温度52℃、热风干燥温度73℃、转换点含水率58%,该工艺下单位能耗3 621. 36 k J/g、叶绿素含量6. 42 mg/g、色泽L*值46. 21、吸湿性7. 19%,综合评分值与预测值拟合度高达99. 632 5%,为红薯叶综合利用奠定了理论基础。