Abstract
Jams are preparations of fruits whose main preserving agent is sugar. Due to this, health concerns of consumers have resulted in a sugar reduction, and its replacement using alternative sweeteners and introducing new ingredients enhancing nutritional properties. In this study, four types of fruits jams (plum, strawberry, apple, and peach), with or without sugar, were prepared using two microalgae biomass, Arthrospira platensis (Spirulina) and Chlorella vulgaris, and Dunaliella salina extract as ingredients at different mix levels of concentrations, 0.10%–0.10%–0.05% respectively, for plum; 0.04%–0.00%–0.01 respectively, for strawberry; 0.06%–0.04%–0.00% respectively, for apple and 0.00%–0.01%–0.04% respectively, for peach. Physicochemical, rheological, and textural parameters were evaluated. Substitution of sugar/fructose syrup in the jam’s preparation caused changes in pH values, solid soluble content, and rheological and textural properties compared to sugar jams. Using sugar or sweeteners as isomalt, stevia and sucralose and microalgae biomass or extract showed significant changes in colour coordinates, however, these differences were not perceptible by the human eye. Jams containing microalgae biomass-extract showed higher G', G'', G*, and η* values than their corresponding control samples. All the jams presented weak-gel characteristics, distinguishing fruit jams. However, the results of weak-gel model analysis suggest that the influence of the different ingredients in the food system depends not only on their concentration but also on the interactions in the gel structure. Strawberry and apple jams showed no significant differences between microalgae biomass-extract samples and control samples, for both sugar and no sugar added jams being the best-obtained samples.
Highlights
Jam is defined as an intermediate moisture food obtained when boiling fruit pulp with sugar, pectin, acid, and other ingredients such as preservatives, colouring agents, and flavouring; and their composition is controlled by law worldwide [1]
The jam formulations were developed based on company experience in creating formulations for the fruit processing industry, producing sugar jams (plum (G), strawberry (S), apple (A), and peach (P)) and no added sugar jams (plum (SG), strawberry (SS), apple (SA), and peach (SP))
Sugar acts as a preservative in gelled products, like jams, by reducing the water activity and enhancing the stability, preventing the growth of yeasts and microbes [1, 18]
Summary
Jam is defined as an intermediate moisture food obtained when boiling fruit pulp with sugar, pectin, acid, and other ingredients such as preservatives, colouring agents, and flavouring; and their composition is controlled by law worldwide [1]. European Food Research and Technology (2021) 247:2565–2578 polyols and especially, natural sweeteners as stevia are becoming more popular for not providing calories but giving sweet flavour to food formulations adding to the pleasure of eating [8, 9] They are used on a large scale by the food industry due to their good technological properties as thickeners or humectants; they are resistant to heat and are not involved in Maillard reactions [10]. Incorporating microalgal biomass in traditional food products, such as bakery products, is a global trend, as several products have been launched worldwide In these cases, microalgae addition has improved freshness and modify firmness, nutritional values, and colour [13, 14]. Microalgae addition in jams has not been studied
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