乳脂肪球膜，作为乳制品中一个独特而珍贵的成分，近年来因其潜在的营养健康作用而备受瞩目。从促进大脑发育到增强免疫力，其多方面的益处正逐步被科学揭示，并开始在多个领域展现广阔的应用前景。
脂质是母乳的重要营养成分之一，以脂肪球形式存在，脂肪球由三层膜包裹着甘油三酯组成，外面包裹着的生物活性膜即乳脂肪球膜(milk fat globule membrane，MFGM)包括糖蛋白、极性脂质等成分[1]。MFGM蛋白包括黏蛋白1、嗜乳脂蛋白、黄嘌呤氧化酶/黄嘌呤脱氢酶等。极性脂质包含磷脂酰胆碱、磷脂酰乙醇胺、磷脂酰肌醇/磷脂酰丝氨酸等[2,3]。随着对母乳成分研究的不断深入，MFGM逐渐得到关注，越来越多的研究集中在MFGM的精准添加和模拟，以满足婴幼儿早期神经发育和认知、免疫调节、生长发育、肠道健康的营养物质。
1.MFGM配料的来源
MFGM配料通过分离、搅打、膜过滤、干燥等工序制成。稀奶油搅打形成奶油粒的过程、无水奶油经融化离心分离，干酪凝乳分离等过程均可作为MFGM配料生产的主要原料。
2.MFGM的加工稳定性
了解MFGM在热处理、均质、混合、干燥等加工环节中的变化规律，对其活性保持具有重要意义。均质处理降低了MFGM表面的磷脂、糖脂和糖蛋白的荧光[4]。生乳在65°C下加热10min，MFGM蛋白开始变性，嗜乳脂蛋白和黄嘌呤氧化酶开始通过分子间二硫键聚集。当温度达到75°C时，乳凝集素的含量显著下降，在95°C热处理时乳凝集素会完全脱落[4]。喷雾干燥处理使MFGM总磷脂含量、磷脂酰胆碱和磷脂酰乙醇胺的相对含量显著下降[5]。
3.MFGM对婴幼儿生长发育的调节作用
3.1 促进神经发育
2月龄婴儿分别喂养添加或不添加MFGM的标准配方乳粉至12月龄，发现MFGM能够提高配方粉喂养婴儿的认知评分，缩小母乳喂养和配方乳粉喂养婴儿之间的认知差距[6]。配方乳粉喂养乳鼠出生后补充MFGM，缩小了与母乳喂养乳鼠之间的神经反射行为成熟的年龄差距，并且提高了其脑磷脂和代谢产物的含量[7]。生长受限的乳鼠出生后灌胃MFGM至断奶，其在行为学测试中的表现得到改善，脑源性神经营养因子的表达显著升高[8]。富含乳磷脂的MFGM干预肥胖母鼠可以促进子代神经发育，并对断奶后高脂饮食诱导的子代认知障碍具有长期的缓解作用[9]。
3.2 调节免疫和肠道健康
婴幼儿补充MFGM可降低急性中耳炎和腹泻的发生风险，并对肺炎球菌疫苗的体液反应具有免疫调节作用[10]。进一步通过代谢组发现补充MFGM能够增加婴儿血液循环中的氨基酸水平，降低微生物代谢产物氧化三甲胺以及促炎细胞因子IL-2的水平[11]。MFGM可以调节配方粉喂养乳鼠肠道菌群，促进其肠道增殖和分化，增加紧密连接蛋白表达，从而促进肠道发育[12]。此外，MFGM可以增加粪便短链脂肪酸水平，从而导致肠系膜淋巴结中调节性T细胞的上调和肠道屏障的增强，改善β-乳球蛋白引起的食物过敏[13]。
3.3 调节代谢
饮食中添加富含MFGM的乳成分可以降低肥胖人群餐后胆固醇、炎症标志物，改善胰岛素敏感性[14]。MFGM可通过抑制脂肪生成并促进白色脂肪棕色化来预防高脂饮食诱导的肥胖[15]，体外实验表明MFGM及其组分PC通过调控过氧化物酶体增殖剂激活受体α促进脂肪细胞棕色化[16]。MFGM干预肥胖母鼠显著增加其子代的身长、尾长、股骨和胫骨长度，并提高其骨量，改善骨组织显微结构，这与子代机体生长激素/胰岛素信号通路的激活有关[17]。
综上，MFGM有助于脑发育、骨健康、增强免疫，促进肠道健康，不同加工处理影响MFGM组成和结构的稳定性。因此，需加大研发力度，创新MFGM绿色分离、制备工艺，发掘MFGM与婴幼儿配方乳粉中其他特征成分的协同功效及作用机制。量选择采用新鲜、天然的食材制作的产品，以保证食品的品质和安全性。
参考文献
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