STLO, INRAE, Institut Agro, 35042, Rennes, France.
University of Lille, Inserm, CHU Lille, Pasteur Institute of Lille, U1167 - RID-AGE, F-59000 Lille, France.
J Dairy Sci. 2021 May;104(5):5265-5278. doi: 10.3168/jds.2020-19529. Epub 2021 Mar 6.
Infant formula (IF) is submitted to several heat treatments during production, which can lead to denaturation or aggregation of proteins and promote Maillard reaction. The objective of this study was to investigate innovative minimal processing routes for the production of first-age IF powder, thus ensuring microbial safety with minimal level of protein denaturation. Three nutritionally complete IF powders were produced at a semi-industrial scale based on ingredients obtained by fresh bovine milk microfiltration (0.8 and 0.1-µm pore size membranes). Low-temperature vacuum evaporation (50°C) and spray-drying (inlet and outlet temperatures of 160 and 70°C, respectively) were conducted to produce the T- formula with no additional heat treatment. The T+ formula was produced with a moderate heat treatment (75°C for 2 min) applied before spray-drying, whereas the T+++ formula received successive heat treatments (72°C for 30 s on the milk; 90°C for 2-3 s before evaporation; 85°C for 2 min before spray-drying), thus mimicking commercial powdered IF. Protein denaturation and Maillard reaction products were followed throughout the production steps and the physicochemical properties of the powders were characterized. The 3 IF powders presented satisfactory physical properties in terms of a, free fat content, glass transition temperature, and solubility index, as well as satisfactory bacteriological quality with a total flora <10 cfu/g and an absence of pathogens when a high level of bacteriological quality of the ingredients was ensured. Protein denaturation occurred mostly during the heat treatments of T+ and T+++ and was limited during the spray-drying process. The IF powder produced without heat treatment (T-) presented a protein denaturation extent (6 ± 4%) significantly lower than that in T+++ (58 ± 0%), but not significantly different from that in T+ (10 ± 4%). Although T- tended to contain less Maillard reaction products than T+ and T+++, the Maillard reaction products did not significantly discriminate the infant formulas in the frame of this work. The present study demonstrated the feasibility of producing at a semi-industrial scale an infant formula being bacteriologically safe and containing a high content of native proteins. Application of a moderate heat treatment before spray-drying could further guarantee the microbiological quality of the IF powders while maintaining a low protein denaturation extent. This study opens up new avenues for the production of minimally processed IF powders.
婴儿配方奶粉（IF）在生产过程中要经过多次热处理，这可能导致蛋白质变性或聚集，并促进美拉德反应。本研究的目的是探索生产第一代 IF 粉末的创新最小加工路线，从而在最低蛋白质变性水平下确保微生物安全性。以通过新鲜牛初乳微滤（0.8 和 0.1-µm 孔径膜）获得的成分，在半工业规模上生产三种营养完全的 IF 粉末。采用低温真空蒸发（50°C）和喷雾干燥（入口和出口温度分别为 160°C 和 70°C）生产 T-配方，不进行额外的热处理。T+配方采用适度的热处理（喷雾干燥前 75°C 处理 2 分钟），而 T+++配方则接受连续的热处理（牛奶中 72°C 处理 30 秒；蒸发前 90°C 处理 2-3 秒；喷雾干燥前 85°C 处理 2 分钟），从而模拟商业粉状 IF。在整个生产过程中跟踪蛋白质变性和美拉德反应产物，并对粉末的物理化学性质进行了表征。3 种 IF 粉末在 a、游离脂肪含量、玻璃化转变温度和溶解度指数方面均表现出满意的物理性质，并且在确保高成分细菌学质量的情况下，具有良好的细菌学质量，总菌群<10cfu/g，无病原体。蛋白质变性主要发生在 T+和 T+++的热处理过程中，在喷雾干燥过程中受到限制。未经过热处理（T-）的 IF 粉末的蛋白质变性程度（6±4%）明显低于 T+++（58±0%），但与 T+（10±4%）无显著差异。尽管 T- 倾向于比 T+和 T+++含有较少的美拉德反应产物，但在本研究框架内，美拉德反应产物并没有显著区分婴儿配方奶粉。本研究证明了在半工业规模上生产具有细菌学安全性且含有高含量天然蛋白质的婴儿配方奶粉的可行性。在喷雾干燥前应用适度的热处理可以进一步保证 IF 粉末的微生物质量，同时保持较低的蛋白质变性程度。本研究为生产最小加工的 IF 粉末开辟了新途径。
