# Improved Food-Processing Techniques to Reduce Isoflavones in Soy-Based Foodstuffs
## 4 Discussion
### Safety Limits for Isoflavones  
The US National Toxicology Program demonstrated in two multigenerational reproductive and carcinogenesis studies that exposure to GEN caused mammary and pituitary gland tumours in female rats, and reproductive impairments in both sexes [31; 32]. The efficient daily dietary exposure was 35 mg/kg body weight, thereby defining the preliminary toxic levels in animals. It has been admitted in classical toxicology that in order to translate a minimal toxic dose of a substance from animals to humans, it has to be divided by the product of various safety factors that range from 1 to 10 [47; 48; 49]. In the case of GEN, three safety factors must be considered. The first is a factor of extrapolation from a LOAEL (lowest observable adverse effect level, which is available for GEN) to NOAEL (no observable adverse effect level). The second is a factor of extrapolation between animals and humans. The third is a factor counting for sensitivity differences among humans. If the commonly admitted values are applied, this brings out a total of 300, even if 184 could be safe enough, as argued by [PERSON] [48]. Regarding soybeans, the NTP assessed only GEN toxicity, thus the question regarding other estrogenic IFs remains unanswered. Because soybean also contains DAI that can be metabolised into a more potent estrogen, i.e., equal [50], it would be safer, in the authors opinion, to consider the toxicity of total IFs. Since no data are available on DAI toxicity, it seems adequate to apply the highest safety factor to total IF measurements, i.e., 300. Such a decision will bring the IF limit for an adult weighing 60 kg to 20 mg/day, and for a 20 kg child to 6.7 mg/day.  
In previous works, multiple soy-based foods from France were analysed for their GEN and DAI contents [25; 26]. Several of them, including roasted soybeans, soy milk, soy galettes, and soy cheese or tofu, could bring up to 50 mg or more per portion. Such amounts clearly justify the work presented here. In this study, we managed to reduce debulled beans' IF levels from 90-100 mg/100 g to 40-52 mg/100 g. Dehulled beans are usually texturized in soy proteins. If it is assumed that texturization does not change the IF content of textured proteins, the latter could be further treated to achieve acceptable IF levels in final foodstuffs, if required. Luckily, this is starting to be the case in France, and at an industrial scale. Repeated water rinsing of textured soy proteins instead of soybeans can reduce their IF content by up to 90%. One plausible explanation for this high IF removal efficiency could be the protein conformational and molecular changes that occur during texturization, as the protein water absorption has been found to increase with denaturation, due to the formation of a protein matrix that is stabilized by hydrophobic interactions [51]. This water treatment of textured proteins was a preliminary result obtained during the implementation of a new industrial recipe, but it failed to reach the RefD. The implementation of drenching and washing of dehulled beans, on the one hand, and rinsing of textured proteins, on the other, would give rise to highly safe soy-based food that may be eaten without any restriction.