Economic analysis of volatile characteristics of Haematococcus pluvialis and the effect of roasting temperature on the profile of volatiles and chemical components

Abstract

Haematococcus pluvialis, an excellent natural source of astaxanthin, is also enriched with protein, PUFA, carbohydrates. However, the off-flavour of H. pluvialis powder has limited its direct application in food products. The characteristic odour diversity of algae depends on the composition and relative concentration of volatile organic compounds (VOCs). The present study sought to characterize the chemical profile of VOCs of H. pluvialis powders to improve its odour and promote its direct application in functional food and feed products. Additionally, the roasting treatment was applied to improve the flavour, and the effect of roasting temperature on VOCs, nutritional components, and antioxidant activity was investigated. A total of 401 VOCs were identified, with esters being the major class of VOCs, accounting for 63.108% of the total volatiles. Esters, ketone, and aldehydes were the major VOCs contributing to the odour of H. pluvialis powders. After roasting for 30 min at different temperatures, most volatiles were increased, except for esters. Several important flavour VOCs, such as β-ionone, geranylacetone, β-cyclocitral, and nonanal derived from carotenoids and fatty acids, were increased with the increase of the roasting temperatures, exhibiting pleasant odours, such as violet-like, fruity, and fresh odours. The biochemical components, pigments, and antioxidant activity were destroyed with varying degrees during roasting. Additionally, the thermal treatment process accelerated the degradation and oxidation of pigment, proteins, and lipids. Furthermore, the Maillard reaction significantly reduced proteins and carbohydrates. The degradation of pigments and fatty acids resulted in the formation of volatile compounds. Finally, 100–120 °C was considered as an appropriate roasting temperature to improve the flavour of H. pluvialis without interfering with the nutrients.