Milk Science
Online ISSN : 2188-0700
Print ISSN : 1343-0289
ISSN-L : 1343-0289
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Original Papers
  • Yomi Watanabe, Lisa Kawasaki, Araki Masuyama
    2020 Volume 69 Issue 2 Pages 63-70
    Published: 2020
    Released: August 08, 2020
    JOURNALS RESTRICTED ACCESS

     Triacylglycerols (TAG) are the major neutral lipids in mammalian breast milk and they are known to have certain unique structural features. In these TAG, 16:0 fatty acids are located predominantly at the sn-2 position, whereas the short chain (SC) and unsaturated fatty acids (FAs) are located largely at the sn-1(3) position. In infant formula, a substitute for human breast milk, the positional distribution of FA in the TAG is of central importance in the compositional design for proper efficacy of lipid absorption and nutrition for the infant. Some infant formulas contain polyunsaturated (PU) FAs to improve nutritional benefits. However, the pancreas lipase used in the conventional method for identifying the FA occupying the sn-2 position of TAG, ISO 6800, is unsuitable for use with oils containing SCFA or PUFA.

     This study aimed to develop an experimental protocol to analyse the FA distribution in the TAG of infant formula. First, lipids in infant formulas were extracted using AOAC Official Method 932.02, generally known as the Röse-Gottlieb method. Recoveries in the range of 88~96% from both liquid and powdered types of formulas were obtained. Because the PUFA contents in a fish oil mixture did not change significantly after extraction with Röse-Gottlieb method, the PUFAs were stable during the extraction procedure.

     The lipids extracted from infant formulas were subjected to Joint JOCS/AOCS official method Ch 3a-19 (JOCS Standard method 2.4.5) to determine the FA in the sn-2 position of TAG; this method is suitable for use with TAG containing SCFA and PUFA. In most of the infant formulas analysed in this study, 16:0 FA was mainly located at the sn-2 position. Docosahexaenoic acid was also located mainly at the sn-2 position in the PUFA-containing formulas.

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Review
  • Junko Nishimura
    2020 Volume 69 Issue 2 Pages 71-82
    Published: 2020
    Released: August 08, 2020
    JOURNALS RESTRICTED ACCESS

     Although Lactobacillus reuteri (Lb. reuteri) is a kind of probiotic lactic acid bacterium (LAB) that is well suited for industrial applications, the fundamental characteristics of this species are relatively unknown. This review therefore examined the probiotic characteristics, carbohydrate metabolism, and current and possible future applications of Lb. reuteri.

     In carbohydrate utilization, sugars are taken up via various cell membrane transporters into cells, and hexose and pentose are metabolized by the phosphoketolase or the pentose phosphate pathways. Several strains of Lb. reuteri are capable of synthesizing extracellular polysaccharides and oligosaccharides. One such polymer is “reuteran”, which contains predominantly alternating (α1→4) and (α1→6) linkages. The production of fructosyl polymers with (β2→6) and (β2→1) linkages has also been produced. Reuteran and fructosyl polymers are extracellularly synthesized by glucansucrases or fructosucrases, respectively. Although the industrial applications of these polymers and enzymes are currently limited, their use is likely to increase in fields such as the dairy industry in the future.

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Review for the JDSA Award 2019
  • Morimasa Tanimoto
    2020 Volume 69 Issue 2 Pages 83-92
    Published: 2020
    Released: August 08, 2020
    JOURNALS RESTRICTED ACCESS

     The properties of food include: (1) physical properties in the region of slight deformation; (2) mechanical properties meaning large deformation region, texture, etc.; and (3) quality characteristics. We focused on the aggregation and coagulation of the milk protein casein and determined the significance of the data obtained for dynamic viscoelasticity. It was observed that dynamic viscoelasticity is useful for understanding the mechanical state of a gel substance and changes to the gel state. Furthermore, the evaluation and application of dynamic viscoelasticity in large deformation are important for studying the various types of milk gels. While researching the physical properties of foods, understanding the process of food production and the characteristics of food products is a prerequisite. Collaboration and exchange of information between engineers and researchers are essential for the advancement of research on properties of food. Research on the physical properties of foods, mainly milk and dairy products, is expected to lead to further development in the future.

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Proceedings of Dairy Science Symposium 2020
1. Abstract of Keynote Lecture
2. Abstract of Invited Lecture
Milkscience, Eureka!
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