Evaluating the physico-chemical, nutritional composition, flavour and sensory properties of raw and grilled plant-based Atlantic salmon (Salmo salar) analogues

Abstract

Atlantic Salmon (Salmo salar) is one of the most captured and farmed salmonids in coastal Canada. These fish are also rich sources of protein and polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, concerns about environmental sustainability, overfishing and the conservation of seafood species as well as the presence of heavy metals, pesticides and microplastics in the ocean have generated a need for the development of seafood analogues using sustainable plant-based ingredients. Plant-based seafood analogues is a term used to describe plant-based foods formulated to mimic the texture and sensory properties of traditional seafood. However, to develop these alternative products, it is important to consider the functionality of the protein source used, as well as the sensory attributes and the consumer acceptability of the final products. Accordingly, the objectives of this study were to: 1) Develop plant-based Atlantic Salmon analogues, with up to 11% protein content, using sustainable plant-based protein ingredients. 2) Evaluate the proximate compositions and protein quality of the developed analogues. 3) Identify and characterize the volatile profiles generated from the formulations. 4) Evaluate how protein concentration impacts the texture and microstructure of the analogues, and 5) Evaluate how protein concentration impacts the sensory attributes including the flavour of the analogues. The protein isolates used for this study were commercially extracted from two pulse seeds: Pea (Pisum sativum L.) (PP 80 and PP 85) and Faba bean, (FB 90) (Vicia faba), both obtained from AGT Foods (Minot, ND USA). Three formulations, PP 80, PP 85 and FB 90 containing 80%, 85% and 90% protein concentration respectively, were developed. In addition to the protein isolates, other ingredients including kappa-carrageenan, dulse flakes (Palmaria palmata), flaxseed oil, lycopene, salts (sodium chloride and calcium chloride) and distilled water were incorporated in the formulations for the plant-based seafood analogues (PBSAs). The analogues were grilled in an oven for 30 minutes at 171 C and evaluated by measuring their proximate compositions using the standard methods from the Association of Official Agricultural Chemists (AOAC). Conversely, protein quality was evaluated by measuring their corresponding amino acid profiles. A gas chromatography-olfactory-mass spectrometry (GC-O-MS) approach was used to identify the volatile organic compounds in the analogues; while the combination of a 9-point Hedonic scale and a Check-All-That-Apply (CATA) questionnaire were used to evaluate the sensory attributes. A sensory wheel with specific descriptors for the aroma profiles was also used to characterize the final analogues developed. The colour coordinates of the samples were tested and then measured using a colorimeter. The, the texture of the samples was evaluated using a Texture Analyzer, and scanning electron microscopy was used to evaluate the microstructure of the analogues. Overall, the analogues containing PP 85 and FB 90 had very similar nutrient profile, compared to those containing PP 80. However, the sensory acceptability test showed that PP 80 had the highest overall rating, although PP 85 was the most preferred for texture, taste and aroma. The GC-O-MS data showed the presence of the ketone, acetophenone, in all three uncooked formulations. However, in the grilled samples, 1-octen-3-ol, hexanal, nonanal and benzaldehyde were the main volatiles present. An increase in protein concentration of the analogues also resulted in a decrease in relative concentrations (μg/L) of the aroma compounds that were also identified in real Atlantic salmon. Colorimeter assays also indicated that PP 80 for both raw and grilled samples had the highest colour difference when compared to Atlantic Salmon. Also, when the grilled PBSA’s, were compared to Atlantic salmon, no significant differences in hardness, cohesiveness and chewiness were observed in the three formulations.