# Effects of Heat Treatment Processes: Health Benefits and Risks to the Consumer
###### Abstract  
Macrolalgae are a biological group that has mainly been used in Asian countries; however, the interest shown by Western society is recent, its application in the industrial sector having increased in the last few decades. Seaweeds are filled with properties which are beneficial to our health. To use them as food and enhance these properties, heat has been used on them. This process alters the bioactive compounds. If we study the levels of moisture, they can vary according to the drying methods used. High values of moisture can lead to a short shelf life due to oxidation, microbial or enzyme activity, so controlling these values is highly recommended. Heat causes enzymatic activity as well as oxidation, which leads to degradation of phenolic compounds in comparison with freeze-drying, which causes fewer losses of these components. Due to the same occurrences, lipid content can also vary, modifying the bioactive compounds and their benefits. Pigments are some of the components most affected by heat, since, through this process, seaweeds or seaweed products can suffer a change in color. Iodine in macroalgae can decrease drastically; on the other hand, protein yield can be greatly enhanced. Some studies showed that the amount of arsenic in raw seaweeds was higher than when they were heat processed, and that arsenic values varied when different heat treatments were applied. Additionally, another study showed that heat can alter protein yield in specific species and have a different effect on other species.  
heat treatment; seaweeds; bioactive compounds; food safety; consumer health +
Footnote †: journal:lack of nutrients, seaweeds played a major role, being rich in several macronutrients and micronutrients, including vitamins, minerals and proteins [5; 6]. Because of their polymers, such as carrageenan, agar and alginate, and their properties for gelling, emulsifying and thickening, they have been used as a novel food [7; 8].  
Seaweeds are an excellent source of bioactive compounds with health-promoting benefits, such as antioxidants, dietary fiber, essential fatty acids, vitamins and minerals, consumption of which has been associated with a lower occurrence of some chronic diseases, such as diabetes, obesity, heart disease and cancer [9; 10]. Due to these beneficial properties, it is necessary to assess how the culinary processes influence and modify the valuable compounds that are sought after in their consumption. With the growing interest in consumption of these organisms, it is crucial to assess how culinary treatment, specifically thermal treatment, alters the bioactive content of edible algae, as the particular methodology has an impact on the biochemical composition [9].  
Utilization of seaweeds normally requires post-harvest dehydration to reduce the water content, which can be up to 85-90% of the biomass [9], preventing decomposition and microbial contamination, increasing shelf life and consumer safety while also aiding the extraction of important chemical constituents [11]. Several techniques have been described for the drying of seaweeds. Sun-drying and oven-drying are the most used, due to their accessibility and relatively low operation cost [11; 12]. However, solar drying is dependent on the climate and exposure to airborne contamination, which can compromise the hygiene of the product [11; 12]. Oven-drying requires a large space, has high energy consumption and leads to component degradation, especially heat-labile compounds [11; 12]. Other methods, such as freeze- or vacuum-drying, are not widely used for commercial purposes, as they are expensive techniques used for the extraction of specific components for specific industries. This review will focus on the available literature regarding drying processes and phytochemical alterations derived from these processes.