Evaluation of physicochemical properties of Nile tilapia skin collagen extracted in acid médium / Avaliação das propriedades físico-químicas do colágeno da pele de tilápia do Nilo extraído em meio ácido

Tilapia has high-temperature tolerance, can breed in captivity, grow fast, and have excellent cost-benefit. Because of these characteristics, this species is of great interest in aquaculture and, currently, the most produced fish in Brazil. However, by increasing tilapia production, there was also a rise in the amount of organic waste, mainly from filleting, which discards 70% of waste. There are many studies on collagen extraction from tilapia skin as an alternative to reduce these residues and add commercial value. In this work, the extraction of protein concentrate was tested using an acid protocol, in which the tilapia skins underwent a pre-treatment in an acid medium and saline precipitation, with variations in time and concentration. After its extraction, the skin was evaluated for ash, moisture, protein, solubility, and pH. The protein concentrate obtained showed low ash contents, and the humidity is within those presented by the literature. The protein concentrate showed levels from 68.73 to 80.58% of protein and a low solubility between 4.03 to 6.93%. In conclusion, acid extraction is a possible means of collagen extraction, and tilapia skin is a good alternative to reuse waste generated in the fish industry.

A tilápia tem tolerância a altas temperaturas, pode se reproduzir em cativeiro, crescer rápido e tem excelente custo-benefício. Por essas características, esta espécie é de grande interesse na aquicultura e, atualmente, o pescado mais produzido no Brasil. No entanto, com o aumento da produção de tilápias, houve também um aumento na quantidade de resíduos orgânicos, principalmente da filetagem, que descarta 70% dos resíduos. Existem muitos estudos sobre a extração de colágeno da pele de tilápia como alternativa para reduzir esses resíduos e agregar valor comercial. Neste trabalho, a extração do concentrado protéico foi testada utilizando um protocolo ácido, no qual as peles de tilápia foram submetidas a um pré-tratamento em meio ácido e precipitação salina, com variações de tempo e concentração. Após sua extração, a pele foi avaliada quanto a cinzas, umidade, proteína, solubilidade e pH. O concentrado protéico obtido apresentou baixos teores de cinzas, e a umidade está dentro dos apresentados pela literatura. O concentrado protéico apresentou teores de 68,73 a 80,58% de proteína e uma baixa solubilidade entre 4,03 a 6,93%. Em conclusão, a extração ácida é um possível meio de extração de colágeno, e a pele de tilápia é uma boa alternativa para reaproveitar os resíduos gerados na indústria de pescados.

Comparative analysis of the use of natural and synthetic antioxidants in chicken meat: an update review.

The search for healthy foods has attracted the industry's attention to developing products that use natural ingredients, including natural antioxidants. Antioxidants act as free radicals or oxygen scavengers, inhibiting lipid oxidation and adversely affecting meat products' sensory and nutritional quality. Several synthetic antioxidants have been used in the meat industry; however, studies point to health risks related to their consumption. Such fact drives research into natural antioxidants extracted from grains, oilseeds, spices, fruits, and vegetables, which may have a health-promoting effect. This manuscript evaluates the effectiveness of several natural antioxidants in improving the quality and shelf life of chicken meat products during processing, storage, and distribution. The potential effects of natural antioxidants widely used in chicken products are also discussed. It can be concluded that these natural antioxidants are possible substitutes for synthetic ones. However, their use can affect the product's characteristics.

Evaluation of physicochemical properties of Nile tilapia skin collagen extracted in acid médium.

Tilapia has high-temperature tolerance, can breed in captivity, grow fast, and have excellent cost-benefit. Because of these characteristics, this species is of great interest in aquaculture and, currently, the most produced fish in Brazil. However, by increasing tilapia production, there was also a rise in the amount of organic waste, mainly from filleting, which discards 70% of waste. There are many studies on collagen extraction from tilapia skin as an alternative to reduce these residues and add commercial value. In this work, the extraction of protein concentrate was tested using an acid protocol, in which the tilapia skins underwent a pre-treatment in an acid medium and saline precipitation, with variations in time and concentration. After its extraction, the skin was evaluated for ash, moisture, protein, solubility, and pH. The protein concentrate obtained showed low ash contents, and the humidity is within those presented by the literature. The protein concentrate showed levels from 68.73 to 80.58% of protein and a low solubility between 4.03 to 6.93%. In conclusion, acid extraction is a possible means of collagen extraction, and tilapia skin is a good alternative to reuse waste generated in the fish industry.

DNA repair and sequence context affect (1)O(2)-induced mutagenesis in bacteria.

Electronic excited molecular oxygen (singlet oxygen, (1)O(2)) is known to damage DNA, yielding mutations. In this work, the mutagenicity induced by (1)O(2) in a defined sequence of DNA was investigated after replication in Escherichia coli mutants deficient for nucleotide and base excision DNA repair pathways. For this purpose a plasmid containing a (1)O(2)-damaged 14 base oligonucleotide was introduced into E.coli by transfection and mutations were screened by hybridization with an oligonucleotide with the original sequence. Mutagenesis was observed in all strains tested, but it was especially high in the BH20 (fpg), AYM57 (fpg mutY) and AYM84 (fpg mutY uvrC) strains. The frequency of mutants in the fpg mutY strain was higher than in the triple mutant fpg mutY uvrC, suggesting that activity of the UvrABC excinuclease can favor the mutagenesis of these lesions. Additionally, most of the mutations were G-->T and G-->C transversions, but this was dependent on the position of the guanine in the sequence and on repair deficiency in the host bacteria. Thus, the kind of repair and the mutagenesis associated with (1)O(2)-induced DNA damage are linked to the context of the damaged sequence.

Mutation spectrum induced by singlet oxygen in Escherichia coli deficient in exonuclease III.

The repair of singlet oxygen (1O2)-induced DNA lesions requires several enzymes of the nucleotide and base excision repair pathways, including exonuclease III and endonuclease IV that are known apurinic/apyrimidinic-endonucleases in Escherichia coli. In order to better understand the relevance of exonuclease III on the repair of these lesions, we investigated the mutagenic events that result from the replication of a 1O2-damaged plasmid in an exonuclease-deficient host (xth). The mutation spectrum in the tRNA supF gene target indicated that the absence of exonuclease III does not change the types of mutations induced by 1O2 (mostly of G:C-->T:A and G:C-->C:G transversions). However, the spectrum shows that the mutations are scattered in the supF gene, which is significatively different from the one obtained in wild-type bacteria. Thus, exonuclease III may act on the repair of 1O2-induced lesions altering the DNA repair sequence specificity.

Induction of the SOS function sfiA in E. coli by systems which generate triplet ketones.

Generation of triplet ketones, either chemically through thermal decomposition of 3-hydroxymethyl-3,4,4-trimethyl-1,2-dioxetane and 3-[N-(pyridino)carbamoyl]methyl-3,4,4-trimethyl-1,2-dioxetane++ + or enzymatically via the aerobic oxidation of isobutyraldehyde trimethylsilyl enol ether catalyzed by horse-radish peroxidase, triggers the SOS function sfiA in E. coli. Although the observed effects are relatively weak and the triplet ketone scavenger tryptophan was ineffective in this system, our results provide evidence for the involvement of triplet ketones in this type of DNA damage. Possible mechanisms are discussed.