Área de Tecnología de Alimentos, Departamento de Ciencia y Tecnología de Alimentos, Facultad de Química, Universidad de la República, Montevideo, Uruguay 11800.
Cátedra de Inmunología, Instituto de Química Biológica, Facultad de Ciencias-Área Inmunología, Departamento de Biociencias, Facultad de Química, Instituto de Higiene, Universidad de la República, Montevideo, Uruguay 11600.
J Dairy Sci. 2020 Jul;103(7):5978-5991. doi: 10.3168/jds.2019-17569. Epub 2020 May 14.
Human milk (HM) constitutes the first immunological barrier and the main source of nutrients and bioactive components for newborns. Immune factors comprise up to 10% of the protein content in HM, where antibodies are the major components (mainly IgA, IgG, and IgM). In addition, antibacterial enzymes such as lysozyme and immunoregulatory factors such as soluble cluster of differentiation 14 (sCD14) and transforming growth factor β2 (TGF-β2) are also present and play important roles in the protection of the infant's health. Donor milk processed in HM banks by Holder pasteurization (HoP; 62.5°C, 30 min) is a safe and valuable resource for preterm newborns that are hospitalized, but is reduced in major immunological components due to thermal inactivation. We hypothesized that high hydrostatic pressure (HHP) and high-pressure homogenization (HPH) are 2 processes that can be used on HM to reduce total bacteria counts while retaining immunological components. We studied the effects of HHP (400, 450, and 500 MPa for 5 min applied at 20°C) and HPH (200, 250, and 300 MPa, milk inlet temperature of 20°C) applied to mature HM, on microbiological and immunological markers (IgA, IgG, IgM, sCD14, and TGF-β2), and compared them with those of traditional HoP in HM samples from healthy donors. The HHP processing between 400 and 500 MPa at 20°C reduced counts of coliform and total aerobic bacteria to undetectable levels (<1.0 log cfu/mL) while achieving approximately 100% of immunological component retention. In particular, comparing median percentages of retention of immunological components for 450 MPa versus HoP, we found 101.5 versus 50.5% for IgA, 89.5 versus 26.0% for IgM, 104.5 versus 75.5% for IgG, 125.0 versus 72.5% for lysozyme, 50.6 versus 0.1% for sCD14, and 88.5 versus 61.1% for TGF-β2, respectively. Regarding HPH processing, at a pressure of 250 MPa and inlet temperature of 20°C, the process showed good potential to reduce coliforms to undetectable levels and total aerobic bacteria to levels slightly above those obtained by HoP. The median percentages of retention of immunological markers for HPH versus HoP were 71.5 versus 52.0%, 71.0 versus 27.0%, 104.0 versus 66.5%, and 30.9 versus 0.2%, for IgA, IgM, IgG, and sCD14, respectively; results did not significantly differ for lysozyme and TGF-β2. The HPH at 300 MPa produced higher inactivation of immunological components, similar to values achieved with HoP.
人乳（HM）构成了第一道免疫屏障，也是新生儿营养和生物活性成分的主要来源。免疫因子占 HM 蛋白质含量的 10%，其中抗体是主要成分（主要为 IgA、IgG 和 IgM）。此外，还存在抗菌酶如溶菌酶和免疫调节因子如可溶性分化簇 14（sCD14）和转化生长因子β2（TGF-β2），它们在保护婴儿健康方面也发挥着重要作用。经 Holder 巴氏消毒（HoP；62.5°C，30 分钟）处理的母乳银行捐赠奶是住院早产儿的一种安全且有价值的资源，但由于热失活，其主要免疫成分减少。我们假设高静压（HHP）和高压均质（HPH）是可以用于 HM 的 2 种工艺，可以在降低总细菌计数的同时保留免疫成分。我们研究了 HHP（400、450 和 500 MPa，20°C 下 5 分钟）和 HPH（200、250 和 300 MPa，牛奶入口温度 20°C）对成熟 HM 中微生物和免疫标志物（IgA、IgG、IgM、sCD14 和 TGF-β2）的影响，并将其与 HM 样本中传统 HoP 进行了比较健康供体。在 20°C 下，400 至 500 MPa 的 HHP 处理可将大肠菌群和总需氧菌的计数降低至无法检测的水平（<1.0 log cfu/mL），同时保留约 100%的免疫成分。特别是，比较 450 MPa 与 HoP 时免疫成分保留的中位数百分比，我们发现 IgA 为 101.5%对 50.5%，IgM 为 89.5%对 26.0%，IgG 为 104.5%对 75.5%，溶菌酶为 125.0%对 72.5%，sCD14 为 50.6%对 0.1%，TGF-β2 为 88.5%对 61.1%。关于 HPH 处理，在 250 MPa 压力和 20°C 入口温度下，该工艺具有很好的潜力，可以将大肠菌群降低至无法检测的水平，总需氧菌数量略高于 HoP 处理的水平。HPH 与 HoP 相比，免疫标志物保留的中位数百分比分别为 IgA 为 71.5%对 52.0%，IgM 为 71.0%对 27.0%，IgG 为 104.0%对 66.5%，sCD14 为 30.9%对 0.2%；溶菌酶和 TGF-β2 的结果没有显著差异。300 MPa 的 HPH 产生了更高的免疫成分失活，与 HoP 相似。
