The main objective of this study was to compare the goodness of fit of five non-linear growth models, i.e. Brody, Gompertz, Logistic, Richards and von Bertalanffy in different animals. It also aimed to evaluate the influence of the shape parameter on the growth curve. To accomplish this task, published growth data of 14 different groups of animals were used and four goodness of fit statistics were adopted: coefficient of determination (R 2), root mean square error (RMSE), Akaike information criterion (AIC) and Bayesian information criterion (BIC). In general, the Richards growth equation provided better fits to experimental data than the other models. However, for some animals, different models exhibited better performance. It was obtained a possible interpretation for the shape parameter, in such a way that can provide useful insights to predict animal growth behavior.

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R E S U M OO presente trabalho teve por objetivo realizar o processo de biodigestão anaeróbia de material plástico polimérico biodegradável à base de fécula de mandioca, utilizando-se de biodigestores de escala laboratorial com modo de operação batelada. Utilizou-se água residual estabilizada de suinocultura como matéria-prima e copos plásticos biodegradáveis produzidos a partir de fécula de mandioca para a produção de biogás. A experiência foi desenvolvida utilizando-se es-ȱȱ³¨ȱàęǰȱȱȱ£ȱŚȱȱȱȱȱȱȱŖǰȱŚŖǰȱŗŘŖȱȱŘŖŖȱȱȱȱ biodegradável nos reatores de cada tratamento, respetivamente. A partir dos resultados obtidos, pode-se concluir que polímeros biodegradáveis produzidos a partir de fécula de mandioca (PBM), apresentam elevada biodegradabilidade ǻ¡ȱȱ³¨ȱȱȱȱ ȱȱ·ȱŝśǰŘƖȱȱŝşǰřƖǰȱǼȱȱȱȱ¨ȱàȱȱȱ àęǯȱ ȱȱ³¨ȱȱ¤ȱȱȱÇȱȱ·ȱȱȱȱȱȬȱ³äȱ ȱ·ȱŗŘŝŚȱȱ Ȭŗ ǯȱȱÇȱȱ¤ȱȱȱǰȱȱ³äȱȱ ȱȱ-¨ȱȱȱę³¨ȱȱȱȱȱ³¨ȱȱ¤ȱ¤ȱȱȱȱȱ ȱȱȱ³¨ȱȱŗŘŖȱȱŘŖŖȱȱȱ ǯȱ Palavras-chave: biocombustíveis, biodegradação, bioenergia, biogás, resíduos agroindustriais. ABSTRACTThe present work aimed to perform the process of anaerobic digestion of biodegradable polymeric material based on cassava starch, by using laboratory-scale digesters running on batch operation. We used stabilized swine wastewater as raw material and degradable plastic cups made from cassava starch for the production of biogas. The experiment was carried out in greenhouses under mesophilic conditions. Four treatments were performed, received concentrations ȱŗŘǯśǰȱřŝǯśȱȱŜŘǯśȱǯ Ȭŗ ǰȱ ȱȱȱȱȱȱŚŖǰȱŗŘŖȱȱŘŖŖȱȱȱȱȱȱȱȱȱ each treatment, respectively. From the partial results obtained, it was possible to conclude that biodegradable cassava starch-based polymers show high biodegradability when subjected to anaerobic digestion in mesophilic phase. The elevated production of biogas in a short time span is another remarkable factor. Due to the easy degradability of the ǰȱȱȱȱ¢ȱȱȱȱ¢ȱȱȱęȱ ȱȱȱ production of volatile acids.

Mathematical models are often used to predict microbial growth in food products. An important class of these models involves the adaptation of classical sigmoid functions, such as the Gompertz and logistic functions. This study aimed to validate the use of the modified Richards model in various situations, which have not previously been tested. The model was obtained through solving a system of two differential equations and could be applied to both isothermal and non-isothermal environments. To test and validate this model, we used published datasets containing data for the growth of Pseudomonas spp. in fish products. The results obtained after fitting the model showed that it could be effectively used to describe and predict the Pseudomonas growth curves under various temperature regimens. However, the influence of the shape parameter on the growth curve is an issue that needs further evaluation.