Evaluation and improvement of technological and nutritional properties of plant-based milk substitutes

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Jeske, Stephanie
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University College Cork
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Plant-based milk substitutes are suspensions of extracted and disintegrated plant material in water. However, nutritional values and physico-chemical properties of these products vary greatly and depend largely on the raw material. Plant-based milk substitutes are perceived to be healthy by consumers, but this study unveiled that most products lack in quality. Only soya-based products showed good nutritional and functional properties. Accordingly, this thesis addresses the investigation of several techniques to improve the nutritional and physico-chemical properties of plant-based milk substitutes. Fermentation in conjunction with enzymatic treatments was used as a tool for sugar reduction in a quinoa-based product. Leuconostoc citreum TR116 was identified as a potent mannitol producer, whereby some of the sweetness was preserved during fermentation. The glucose content was reduced by 40% and the glycaemic load by 35% compared to the untreated control. Moreover, a quinoa-based milk substitute was treated with proteolytic enzymes to improve protein stability and functionality. It was found that endoproteases were the most effective to increase the protein solubility. At the same time, product properties, like foaming or colloidal stability were not affected considerably. The protein content of most commercial plant-based milk substitutes was found to be less than 0.5%. Therefore, lentil protein isolates were investigated as a protein enriching ingredient. Isoelectric precipitation and ultrafiltration were investigated as potential extraction methods for the production of protein isolates from brown lentils. Overall, both lentil protein isolates exhibited promising performances, while scoring better environmental standards when compared to cow milk proteins. Ultrafiltration resulted in a more pure protein isolate (93.7%) that exhibited better functional properties, such as solubility, emulsifying stability and gelling properties. Based on these results the lentil protein isolate obtained by ultrafiltration was chosen to create emulsions with a protein and fat content similar to cow’s milk. With high-pressure homogenisation at 900 bar and a heat treatment at 85 °C for 2 minutes emulsions with good colloidal stability (2%/h), appearance, textural and organoleptic profiles were created. These studies assessed the broad range of products available and provided a variety of methods for the formulation of nutritional and functional improved plant-based milk substitutes.
Plant-based milk substitutes , Quinoa , Lentils , Protein , Emulsions
Jeske, S. 2018. Evaluation and improvement of technological and nutritional properties of plant-based milk substitutes. PhD Thesis, University College Cork.