# Effects of Heat Treatment Processes: Health Benefits and Risks to the Consumer
## 7 The Effect of Heat on Seaweed-Based Products  
Seafood, including seaweeds, fishes, mollusks and crustaceans are the biggest contributors of arsenic in our diets. This chemical is highly toxic for humans. [PERSON] et al. [39] studied the use of heat on four different species of seaweeds to see its influence on the quantity of arsenic. This study presented the following graphic, showing the analysis made of seaweeds, before and after heat treatment.  
As seen in Figure 1, in all species, the amount of arsenic reduced when the seaweeds were subjected to heat treatment. The authors also analyzed the cooking water and, as shown, these waters contained large amounts of arsenic [39].  
Another study was made to evaluate the proteins in seaweeds. The seaweeds used were _Palmaria palmata_ (Rhodophyta) and _Alaria esculenta_ (Phaeophyceaeae), and they were subjected to a heat process, namely boiling. In this study, the samples were also submitted to a gastrointestinal tract simulator to see if, during digestion, the measured proteins changed. In the first species, the results showed that there was an increase from 86% to 109% in the amino acid content. This means that by boiling this seaweed for 15-30 min, the amount of protein available was much greater then when it was raw. It has also been shown that, compared with meat protein, it supplies an adequate intake of protein for our body. If we examine the data on _A. esculenta_, the proteins in this species did not change, which means that in this seaweed, the process of heating did not influence its content [36].  
In another study, Indonesian brown seaweeds were analyzed to see if heat treatment would affect four different components, these being fucoxanthin, antioxidant activity, total phenolic content and color stability; however, in this review, we will highlight the first and the second compounds [12]. These seaweeds were subjected to four different heat processes: boiling, blanching, steaming and sterilizing (Figure 2). Fucoxanthin is abundant in brown seaweeds and it has several health benefits. By putting the seaweeds through the four heat treatments, we obtained different results. In Figure 2, we can see these differences accordingly [12]. When raw/fresh, the amount of fucoxanthin in the seaweed was very low; however, when heated, these values increase. As we can see, the heat process that is most beneficial is blanching, followed by boiling, then steaming and sterilizing [12].  
Figure 1: Total arsenic concentrations in kombu, wakame, nori and sea lettuce seaweed samples before and after being cooked, and in their cooking water and dialysates obtained after subjecting these cooked seaweeds to an in vitro gastrointestinal digestion [39].  
Figure 2: Fucoxanthin content in fresh and thermally processed in _S. licifolium_. Values are express in \(\upmu\)g/mL [12].  
Brown seaweeds contain phloroglucinol phenolics and phlorotannin, which have highly beneficial biological activities, such as anticancer, antioxidant and antidiabetic activities, and others. Therefore, finding ways to enhance these benefits is very important. In another study, the results showed that the total phenolic content decreased; however, they explained it by the high temperature that the algae were submitted to, showing that heat treatment can have benefits when applied correctly, but also have the contrary effect when applied incorrectly [12].