Are seaweeds the food of the future? Challenges for its conservation and introduction in the Portuguese diet

Abstract

Introduction: Seaweeds are well known for their nutritional value [1]. The ALGA4FOOD project [https://alga4food.wixsite.com/pt-pt] [2] aims: i) researching new seaweed conservation processes (e.g. lyophilization, pascalization, MAP, etc.) which optimize functional and organoleptic characteristics; ii) develop strategies for its introduction in the Portuguese diet.

Materials and methods¹: Raw Materials: Seven seweed species (Ulva rigida, Codium tomentosum, Undaria pinnatifida, Saccorhiza polyschides, Gracilaria gracilis, Osmundea pinnatifida, Chondracanthus teedei var. Lusitanicus) were collected in north and central Portugal. Porphyra sp. and Ulva rigida for sensorial analysis were cultivated in an IMTA system. Instrumental Analysis: Each seaweed was frozen with liquid nitrogen and ground. Samples were maintained at −20 °C until microextraction by HS-SPME, using 30 g of fresh seaweed and 104 g of milli-Q water with 30% NaCl (PA). Ulva rigida was also dried and 6.75 g of the dried seaweed and 117 g of the saline solution were used. Compounds extracted were analyzed and identified by GC-MS. Product Development and Sensory Analysis: Dried pastas enriched with U. rigida and Porphyra sp. were developed and affective acceptance tests, using as control a 100% semolina (Triticum durum) pasta, were performed. The panel was composed by 60 untrained testers, and a structured hedonic scale of 1 to 9 points was used for the evaluation of appearance, color, aroma, texture, flavour, overall impression and food suitability. Data was submitted to analysis of variance (ANOVA), and Tukey’s multiple comparison tests.

Results: Instrumental analysis: GC-MS identified 57 different organic compounds (167 in total): 28 aldehydes, 4 alcohols; 10 hydrocarbons; 3 ethers; 8 ketones; 4 other functional groups (1 containing sulphur, 2 iodine and 1 bromine). For U. rigida, results showed that the main compounds contributing for its fresh flavour profile (β-ionone and 2,4-decadienal) were different from those for the dried seaweed, meaning that fresh U. rigida has a higher aromatic richness than the dried one. Sensory analysis: The results showed no significant differences between the average values for texture, flavour, overall impression and food suitability. However, the appearance, colour and aroma attributes were significantly different particularly for the control and Porphyra sp. formulations [3].

Discussion and conclusions: The exploratory process showed that both instrumental and sensorial analysis, as well as the concepts underlying cooking creativity [3], are of great value for the development of new seaweed food products. GC-MS technique, together with sensory analysis, showed similarities between Undaria pinnatifida and collard greens (Brassica oleracea var. Acephala). Based on this, the seaweed was introduced in the traditional soup “caldoverde”, and preliminary tests showed good acceptance. Sensory analysis of pasta showed that green seaweed, due to their subtle maritime flavour, have a greater potential for cooking applications than the red seaweed [2,3].

Notes

1 This study was carried out in accord with the updated Helsinki Declaration.