It is known that PSE meat present important functional defects, such as low water holding capacity and ultimate pH, which may compromise the quality of further-processed meat products. In this study, L* (lightness), a* (redness), and b* (yellowness) values of 500 chicken breast fillets were determined using a portable colorimeter (Minolta, model CR-400) in a commercial processing plant. Fillets were considered pale when their L* was ≥49. Out of those samples, 30 fillets with normal color and 30 pale fillets were evaluated as to pH, drip loss, cooking loss, water holding capacity, shear force, and submitted to sensorial analysis. An incidence of 10.20% PSE meat was determined. Pale and normal fillets presented significantly different (p≤0.05) pH values, L* and a* values, water holding capacity, drip loss, and cooking loss, demonstrating changes in the physical properties of PSE meat. Shear force and sensorial characteristics were not different (p>0.05) between pale and normal fillets. Despite the significant differences in meat physical properties, these were not perceived by consumers in terms of tenderness, aspect, and flavor. The observed incidence of PSE may cause losses due to its low water retention capacity. INTRODUCTIONPoultry meat production has undergone many changes in the last few years. Parts are increasingly sold relative to whole carcasses. Moreover, there is an increasing number of further-processed products, such as nuggets, breaded and other ready-to-cook and ready-to-eat products, available in the market. However, the quality of these products is directly related to the quality of the meat used to prepare them.According to the Brazilian Poultry Association (União Brasileira de Avicultura -UBA, 2008), Brazilian chicken production exceeded the volumes sold in previous years both in the domestic and international markets. Exporters expect to obtain significant increase in sales, particularly as new markets are opened. One of the factors that allowed Brazil to become the largest global chicken meat exporter in terms of revenue was the increase in the sales of chicken parts and further-processed products, which have higher added value.A significant proportion of chickens is deboned for breast exports, and consequently, meat quality defects, such as PSE (pale, dry, and exudative meat), result in important losses for chicken meat industry. In addition, taking into account the increasing number of further-processed chicken meat products in the last few years, it is essential for processors to have correct information on PSE meat (Komiyama, 2006). PSE meat is a meat quality defect that affects important meat physical properties, such as water holding capacity and ultimate pH, which may reduce the quality of further processed chicken meat products (Komiyama, 2006
RESUMO:A codigestão dos dejetos de suínos e dos resíduos lipídicos vem sendo amplamente explorada, com melhorias na degradação dos substratos em digestão e, consequentemente, dos rendimentos de biogás. Assim, foram avaliados os desempenhos de biodigestores abastecidos com dejetos de suínos e crescentes níveis de óleo de descarte, por meio das produções e potenciais de produção de biogás, reduções dos teores de sólidos totais (ST), sólidos voláteis (SV) e da demanda química de oxigênio (DQO). Para o desenvolvimento do ensaio de codigestão, foram preparados substratos compostos por dejetos de suínos, óleo de descarte (nas proporções de 0; 2; 4; 6; 8; 10 e 12% de óleo em relação aos teores de ST do substrato), água para diluição destes resíduos e inóculo, contendo teor inicial de 4,0% de ST e abastecimento dos biodigestores batelada. As máximas reduções de ST e SV foram de 36,8 e 41,1% e ocorreram nos níveis de 5,2 e 5,8% de óleo aos substratos. As inclusões de 5,4 e 6,1% de óleo permitiram o alcance de potenciais de 222,9 e 263,6 litros de biogás por kg de ST e SV adicionados, que foram superiores em 10,8 e 5,5% aos rendimentos observados para a dose contendo 0% de óleo. A inclusão de óleo na composição de substratos contendo dejetos de suínos nas doses entre 5 e 6% melhora os rendimentos de biogás. PALAVRAS-CHAVE:biodigestor, suinocultura, sólidos totais, sólidos voláteis. ANAEROBIC CO-DIGESTION OF SWINE MANURE AND INCREASING LEVELS OF DISCARDED OILABSTRACT: Swine manure and lipid residue co-digestion has been widely explored with improvements in substrate degradation, digestion and consequently biogas yield. Thus, we evaluated performance of digesters supplied with swine manure and increasing discarded oil levels, by means of potential of biogas production, and reductions of total solid content (TS), volatile solids (VS) and chemical oxygen demand (COD). To develop co-digestion tests, we prepared substrates composed by swine manure, discarded oil (with 0, 2, 4, 6, 8, 10 and 12% oil in TS substrate), water for dilution of residues and inoculum, having a initial concentration at 4% TS to supply batch-digesters. Maximum TS and VS reductions were 36.8 and 41.1% and occurred at 5.2 and 5.8% oil in substrate. Inclusions of 5.4 and 6.1% oil allowed a potential production range of 222.9 and 263.6 liters of biogas per TS and VS kilogram, which were superior in 10.8 and 5.5 to the observed yields for initial dose of 0% oil. Oil included into substrate with swine manure at doses between 5 and 6% have improved biogas yield. KEYWORDS: digester, swine industry, total solids, volatile solids INTRODUÇÃOA biodigestão anaeróbia é uma técnica amplamente empregada para o tratamento e a reciclagem dos dejetos de suínos, responsáveis pela estabilização da matéria orgânica e a formação
Anaerobic digestion of crude glycerin (CG) along with animal waste has been an excellent option for increasing the production of biogas and methane to achieve efficiency in the treatment of both residues. This study aimed to evaluate improvements in specific productions of biogas and methane, reductions in solid and fibrous components in substrates prepared with dairy cattle manure and CG (containing 14 % glycerol). With these residues, experimental substrates were prepared and placed in 25 batch digesters. Initial content of the TS in the influent was 4 % and CG was added in increasing doses (0, 5, 10, 15 and 20 % relative to total solids (TS) of the influent). Results were submitted to ANOVA and orthogonal contrasts to assess the effects of linear and quadratic order and thereby estimate the optimal CG doses through the adjusted models. The highest values for specific production of methane (0.19 and 0.26 L g −1 of TS and volatile solids (VS) added, respectively) were reached with the CG inclusions of 6 and 8 %, respectively. Total production of biogas with the inclusion of 6 % CG was 11 % higher when compared to the control treatment. The largest reduction in VS (48 %) was achieved with the addition of 4 % CG. Addition of CG at levels between 3 and 8 % improved the efficiency of the process of anaerobic digestion with dairy cattle manure.
This study aimed to obtain the best dose of waste cooking oil inclusion for the co-digestion of substrates prepared with dairy cattle and swine manure in order to maximize solids reductions and biogas yield. Analyses of total solids (TS), volatile solids (VS), and neutral detergent fiber (NDF) were performed during the loading and unloading of digesters, while biogas yield was measured twice a week. The maximum reduction in VS (51.4%) was reached with the inclusion of up to 54.6g waste cooking oil.kg manure-1. Maximum NDF degradation occurred with inclusions of up to 69.4g waste cooking oil.kg manure-1. Inclusions of up to 64g of waste cooking oil.kg manure-1 provided specific biogas yield of 291.4 and 251.0L biogas.kg VS-1 added to substrates with swine and cattle manure, respectively. Adding oil at doses between 45.1 and 69.4g waste cooking oil kg manure-1 to substrates composed of cattle or swine manure maximizes reductions of solids and fibrous constituents and enhances specific biogas yield. Furthermore, swine manure supports higher doses of waste cooking oil.
The use of organic compost in pasture fertilization is a form of recycling nutrients contained in waste and reducing chemical fertilizer use. To perform pasture fertilization, however, grass responses to doses of organic composts must be known. Thus, the objective of this study was to find the best dose of laying hen organic compost to maximize the productive, morphogenetic, structural, and nutritional responses of Paiagu as and Piatã grasses. A completely randomized factorial (4 £ 2) design was used, composed of organic compost doses (0, 400, 800, and 1,200 kg equivalent N.ha ¡1) and two cultivars (Piatã and Paiagu as) of Urochloa brizantha grass with three replicates per treatment, assessed during four successive cuts. The parameters evaluated were dry matter yield (DM) of shoots and roots, leaf appearance rate (LAR), leaf elongation rate (LER), phyllochron, pseudoculm elongation rate (PER), final leaf length (FLL), number of green leaves (NGL), and senescence rate (SR). The nutritional value of the grasses was also assessed through contents of dry matter, organic matter, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber, cellulose, hemicellulose, lignin, and in vitro organic matter digestibility (IVOMD). DM yields of both shoot and root increased due to nitrogen increase and Paiagu as grass had the highest yields (P < 0.01). The best organic compost doses ranged from 640 to 950 kg of equivalent N.ha ¡1 for most morphogenic and structural grass characteristics. The chemical composition of grasses was not influenced (P > 0.05) by doses of organic compost. Levels of 8.05% CP, 67.10% NDF, and 65.14% IVOMD were observed for cultivar Paiagu as, while for cultivar Piatã these values were 7.58% CP, 70.32% NDF, and 63.38% IVOMD. It is concluded that high doses of an organic compost are required (in equivalent N) for cultivars to reach the highest growth rates and that Paiagu as grass has higher dry matter yield, higher growth rates, and better chemical composition when compared to Piatã grass in similar organic fertilization conditions.
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