Comprehensive oligosaccharide profiling of commercial almond milk, soy milk, and soy flour

Authors: HUANG, YU-PING - University Of California, Davis; BRUNA, PAVIANI - University Of California, Davis; Fukagawa, Naomi; BARILE, DANIELA - University Of California, Davis

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2022
Publication Date: 12/21/2022
Citation: Huang, Y., Bruna, P., Fukagawa, N.K., Barile, D. 2022. Comprehensive oligosaccharide profiling of commercial almond milk, soy milk, and soy flour. Food Chemistry. 409:135267. https://doi.org/10.1016/j.foodchem.2022.135267.
DOI: https://doi.org/10.1016/j.foodchem.2022.135267

Interpretive Summary: Non-digestible oligosaccharides (NDO) are carbohydrates with different sizes ranging from simple sugars to polysaccharides and are resistant to digestion in the upper gastrointestinal tract. Almond milk, soy milk, and soy flour are dietary sources of NDO that could affect human health. Depending on the structures, NDO may be utilized by beneficial gut bacteria, such as Bifidobacterium and Lactobacillus, to promote their growth and activity. The selective stimulation of the growth and activity of beneficial bacteria is associated with multiple potential advantages to human health, such as reducing the risk of colorectal cancer, modulating the immune system, improving mineral absorption, and regulating lipid metabolism. As consurmers' preference to consume more plant-based foods increases, it has become important to understand the content of NDO in different products available in the marketplace. Soy milk is a traditional beverage in several Asian countries and plant-based beverages serve as an alternative for consumers who are allergic to cow's milk. This study measured the amount of 3 NDO, raffinose, stachyose and verbascose, in commercial products using novel analytical chemistry approaches. In addition to concentrations of these NDO's, 48-82 oligosaccharides with various structures were identified, including a novel compound found in almond milk in significant abundance. The impact of these compounds on biological responses in humans or animals remains to be determined.

Technical Abstract: Almond milk, soy milk, and soy flour are dietary sources of oligosaccharides that could affect human health. This study quantified the oligosaccharides raffinose, stachyose, and verbascose in commercial products by high-performance anion-exchange chromatography-pulsed amperometric detection (HPAE-PAD). The extraction and quantification methods were optimized and validated to assure measurement accuracy and repeatability (91–107% recovery and 0.0–5.4% intra- and inter-day RSD). The summed concentration of raffinose, stachyose, and verbascose was in the range of 0.118–0.194 mg/g in almond milk, 4.3–6.4 mg/g in soy milk, 74–77 mg/g in defatted soy milk, and 4.8–57 mg/g in full-fat soy four. A comprehensive oligosaccharide profiling was conducted with liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 48–82 oligosaccharides with various structures (e.g., Hex3–8, ciceritol, and Hex2–3Glycerol1) were identified in the products. Besides, novel compounds, 2,3-butanediol glycosides, were identified in almond milk in significant abundance.