Abstract
BACKGROUND: During the industrial production of 휷-glucan, a protein-rich fraction remains as a by-product. Recovery of this protein as oat protein concentrate (OPC) results in a source of cereal protein for food and improves the overall economy of the process. In this study, a yoghurt-type product is developed by lactic acid fermentation of an OPC suspension after subjection to heat treatment to assure starch gelatinization.
RESULTS: In detail, the process of yoghurt production involved an initial heating step to 90 ∘C, followed by 24 h fermentation with a starter culture consisting of Lactobacillus delbrueckii subsp. bulgaricus und Streptococcus thermophilus. The resulting yoghurt-type product was mildly sour (pH 4.2) with a certain amount of lactic acid (3.3 ± 0.2 g kg−1) and contained 4.9 × 106 cfu g−1 lactobacillus after 24 h fermentation. Scanning electron microscopy revealed a porous network presumably built up from the gelatinized starch fraction containing aggregated structures, between which were assumed to be aggregated oat proteins. Moreover, to a limited extent, proteolysis occurred during fermentation. Thus some of the proteolytic enzymes present in the yoghurt culture cleaved oat protein and released peptides. However, the effect on essential amino acids was small.
CONCLUSION: The results of this study provide a deeper knowledge into the role of starch and protein in fermented OPC yoghurts. The structure of fermented OPC verifies the applicability of oat protein as an alternative source for yoghurt-type products.
RESULTS: In detail, the process of yoghurt production involved an initial heating step to 90 ∘C, followed by 24 h fermentation with a starter culture consisting of Lactobacillus delbrueckii subsp. bulgaricus und Streptococcus thermophilus. The resulting yoghurt-type product was mildly sour (pH 4.2) with a certain amount of lactic acid (3.3 ± 0.2 g kg−1) and contained 4.9 × 106 cfu g−1 lactobacillus after 24 h fermentation. Scanning electron microscopy revealed a porous network presumably built up from the gelatinized starch fraction containing aggregated structures, between which were assumed to be aggregated oat proteins. Moreover, to a limited extent, proteolysis occurred during fermentation. Thus some of the proteolytic enzymes present in the yoghurt culture cleaved oat protein and released peptides. However, the effect on essential amino acids was small.
CONCLUSION: The results of this study provide a deeper knowledge into the role of starch and protein in fermented OPC yoghurts. The structure of fermented OPC verifies the applicability of oat protein as an alternative source for yoghurt-type products.
| Original language | English |
|---|---|
| Pages (from-to) | 5852-5857 |
| Journal | Journal of the Science of Food and Agriculture |
| Volume | 99 |
| Issue number | 13 |
| Early online date | Jun 2019 |
| DOIs | |
| Publication status | Published - 1 Oct 2019 |
| MoE publication type | A1 Journal article-refereed |
Funding
This project is part of ERA-NET SUSFOOD OATPRO. The authors thank the national funding agencies: Ministry of Agriculture and Forestry (MMM, Finland, grant number 233/213/2015), the Federal Ministry of Education and Research (BMBF, Projekträger Jülich, Germany, grant number 031A661) and the Romanian National Authority for Scientific Research and Innovation (CCCDI-UEFISCDI, Romania, grant number 3/02.11.2015).
Keywords
- oat protein concentrate
- lactid acid fermentation
- non-dairy yoghurt
- plant proteins