The development of fermented pea protein-coconut milk beverage : a thesis submitted in partial fulfilment of the requirement for the degree of Master of Food Technology, Massey University, Albany, New Zealand

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Most commercially available probiotic products are dairy-based and are associated with consumer health challenges such as lactose intolerance and allergenicity due to milk proteins. Therefore, a strong consumer interest in searching for alternative products and ingredients that can deliver similar health benefits to dairy-based products. Plant protein is an important nutrient for the normal growth and functioning of the human body. Pea protein is of interest to food manufacturers due to its high nutritive value. However, it is characterised by a strong off-flavour (beany flavour) making it difficult to formulate into acceptable consumer food products. The main aim of this study was to reduce the beany off-flavour of commercial pea protein powder intended for the production of an organic fermented pea protein-coconut milk beverage. This research was conducted in three main phases. In Phase 1, salt extraction and isoelectric precipitation methods were used to further purify commercial pea protein powder (Roquette S85F, France). After purification, the yellow commercial pea protein powder (b* = 16.32±0.09) had transformed into a white pea protein paste (b* = 6.86±0.12). Phase 2 investigated the reduction of the beany off-flavour by fermentation of a novel fermented pea protein-coconut milk beverage. In this phase, the refined pea protein paste (phase 1) was added to organic coconut milk (Ceres Organics, Auckland) and then fermented by a mixed lactic culture (VEGE 053 LYO). The single factor test and orthogonal experimental design were used to determine the optimum fermentation conditions of the fermented pea protein-coconut milk beverage. In these experiments, three fermentation temperatures (37 ℃, 40 ℃, 43 ℃) with three protein concentrations (3%, 5%, 7%, w /v) and three fermentation times (8, 10 and 12 h) were used to conduct nine experimental treatments (formulations). The three best fermented beverages were selected based on viable cell counts (VCCs) and sensory evaluation by a semi-trained sensory panel (n=18). These three best samples were further evaluated by a consumer sensory panel (n=90). The fermented beverage containing 3% pea protein and fermented at 40 °C /8 h was evaluated as the best product by the consumer sensory panelists. The final selected formulation had the highest viable cell counts (8.78±0.21 log CFU /mL) and overall mean sensory acceptability scores (6.2±0.50). Other parameters determined in the final formulation of the fermented beverage were pH, titratable acidity (T.A.), colour and crude protein. During fermentation for 8 h, the pH decreased from 6.15±0.13 to 4.29±0.02, while the T.A. increased from 0.09%±0.01 to 0.52%±0.03. Colour changed significantly (p<0.01), whereas there was no significant (p>0.05) difference in the protein content of the fermented pea protein-coconut milk beverage during fermentation. In the third phase, the stability of the fermented beverage during storage (4 °C) for 21 days, was determined by measuring pH and colour as well as the analysis of protein and sensory characteristics. A semi-trained sensory panel (n=15) evaluated the fresh and stored beverage for various sensory characteristics including overall acceptance using the 9-point hedonic scale. During storage of the beverage, the pH, titratable acidity, cell counts and colour changed significantly (p<0.05). By the end of storage, the pH had decreased from 4.43±0.03 to 4.38±0.02 (p<0.05), while T.A. increased slightly. The sensory characteristics were stable during storage. Despite the changes in the physical-chemical characteristics of the fermented beverage, the product was still found to be acceptable by a semi-trained sensory panel following storage for 21 days.
Fermented beverages, Peas, Plant proteins as food, Coconut