## 4 Discussion
Flavonoids are phenolic compounds with strong antioxidant activity by scavenging free radicals based on ET (electron transfer) mechanisms (DPPH) or by chelating transition metals (FRAP). Results obtained show that _Pleurotus_ spp. flour had strong antioxidant activity through the FRAP method and was correlated with the capacity of total free amino acids (chelation metals) and in a low manner with phenol content and flavonoids. Almond powder has a high content of soluble proteins but with low antioxidant activity, an effect demonstrated by both antioxidant methods. For the spirulina powder, the antioxidant effect may be due to c-phyocyanins according to [PERSON] et. al., 2005 [61]. These compounds are known as the main light-harvesting protein pigment with nutritional and therapeutical properties. Mesophilic aerobic bacteria and fungi are two of the most common types of microorganisms responsible for food spoilage. To prevent the contamination of finished food products with spoilage microorganisms, it is important to maintain a high level of hygiene throughout the entire food processing and handling chain. Preventing the contamination of food products with spoilage microorganisms requires a combination of good hygiene practices, effective sanitation protocols and ongoing monitoring and quality control. Results obtained for the TAMC and TYMC assessments indicate \(<\)10 CFU/g values for the yeast and almond powders. Pea, spirulina and _Pleurotus_ spp. powders had \(>\) 3 \(\times\) 10\({}^{3}\) microbial contamination levels. If for pea and spirulina powders the microbial load is considered acceptable according to specific standards [52; 53], for _Pleurotus_ spp. powder, TAMC value of 4.6 \(\times\) 10\({}^{5}\) CFU/g \(-\) 5.66 log \(\pm\) 0.1 CFU/g and TYMC of 2.7 \(\times\) 10\({}^{3}\) \(-\) 3.43 log \(\pm\) 0.18 CFU/g are exceeding standard limits and cannot be considered suitable for integration for consumption or for composition of other products. As for determinations regarding \(\beta\)-glucuronidase positive _Escherichia coli_, neither of the samples tested positive, results being in accordance with standardized requirements [80]. Another category of microorganisms that are present in food in poor hygiene cases are those of the family _Enterobacteriaceae_. Bacteria from the _Enterobacteriaceae_ family are commonly found in either dry or humid environments, are sensitive to heat treatment and sanitation and are desirable to be monitored in food environments. The presence of _Enterobacteriaceae_ in post-hygienic processes may draw attention to the inefficiency of hygiene procedures. Our results indicate values of <10 CFU/g for yeast, pea, almond and spirulina powders. According to standardized requirements [54], these results comply. _Pleurotus_ spp. powder showed a contamination of 5.2 \(\times\) 10\({}^{3}-3.72\) log \(\pm\) 0.27 CFU/g that exceeds standard limitations. These results indicate a high microbial contamination risk for the _Pleurotus_ spp. powder. In order to exploit its beneficial effects, decontamination pre-treatments are necessary. The assessment of toxicity of any given substance that is intended to be exposed to living organisms relies on in vitro evaluation of the dose-response. The dose-response relationship, or exposure-response relationship describes the magnitude of the response of an organism as a function of exposure (or doses) to a stimulus or stressor (usually a chemical) after a certain exposure time. Results obtained demonstrate that tested ingredients have an impact on the metabolic activity of cells--as MTT assay results indicate, and affect the cells' integrity, provoking leakage of DNA. All in all, slow or delayed metabolic cellular activity indicates loss of balance and survival cues from the microenvironment. Such modifications do not support proper development and healthy homeostasis of mature tissues [81]. Here, we struggle with a debacle, as for some ingredients the recommended dosage for optimal effects is cytotoxic.