Dietary oxidized poultry offal fat: performance, carcass and meat composition, and oxidative stability of frozen thigh meat of broiler chickens ABSTRACT -Two hundred male Ross broiler chicks were raised from 10 to 40 days of age and fed a corn-soy diet with 4% of fresh or oxidized poultry offal fat to evaluate the effects of dietary fat quality on broiler performance and on oxidative stability of frozen thigh meat during storage. Fresh poultry fat, characterized by low concentration of oxidation products determined by specific absorbances of 5.80 and 0.69 at 232 and 270 nm, respectively, was supplied by a local renderer and stored frozen (-18 o C) until diets were produced. Oxidized poultry fat was obtained by heating the fresh poultry fat in a fryer at 110-120 o C until specific absorbances reached 11.33 (at 232 nm) and 2.31 (at 270 nm), which show increased concentration of oxidation compounds. At 41 days of age, 136 birds were slaughtered and carcass characteristics were evaluated. Skinless and deboned raw thigh meat was packed and stored for 9 months in a non-illuminated freezer at -20 o C. Thiobarbituric acid reactive substances (TBARS) were assessed monthly in the frozen samples to evaluate the oxidative status of stored meat. Birds performance and carcass characteristics were not affected by the presence of oxidized poultry fat in the diet. After six months of storage, the oxidative stability of frozen thigh meat from broilers fed oxidized poultry fat was reduced, indicated by higher TBARS values.Key Words: carcass and meat yield, chicken meat quality, lipid oxidation, meat color, TBARS IntroduçãoNa avicultura moderna, óleos e gorduras são incorporados às dietas objetivando, principalmente, fornecer grande quantidade de energia e ácidos graxos essenciais, melhorar a conversão alimentar e a palatabilidade das rações, reduzir o incremento calórico, facilitar a absorção das vitaminas lipossolúveis, além de apresentar outras vantagens operacionais na fábrica de rações.

Um aumento no índice de peróxido diretamente proporcional à radiação absorvida por grãos foi observado por Hanis et al. (1988), entretanto, mesmo pertencendo à classe dos constituintes de alimentos mais sensíveis à irradiação, em doses superiores a 10 kGy, não se observou alteração significativa nos lipídios dos cereais.

Background: The properties of plants with food preservation potential are well known since the antiquity. In recent years, the use of herbs and spices to improve the sensory characteristics and to extend the shelf-life of foods has been growing. Objectives: To compare oregano (Origanum vulgare L.) and sage (Salvia officinalis L.) as a natural antioxidant in balls of chicken breast and added 0.50% salt. Methods: Samples of chicken meatballs were pre-cooked for 8 minutes in a water bath at 80º C, and packaged in polyethylene bags with three layers, specific for vacuum cooking and high temperatures. The samples were separated into three groups: control (just salt), 0.10% oregano (dry plant) and sage 0.10% (dry plant), stored at -20º C for 144 hours. The tests to verify the formation of hexanal in samples were performed in the period of 0, 48, 96 and 144 hours of refrigerated storage. The determination of hexanal, extracted by micro-extraction (headspace solid phase micro-extraction - HS-SPME), was used as an indicator of the lipid oxidation of the samples. The analysis was conducted by a gas chromatograph coupled with a mass detector (GC-MS). The method was evaluated according to the validation parameters such as linearity, repeatability and detection limit. The extraction was conducted at 70º C using a fiber (DVD / CAR / PDMS) exposed for 20 minutes in the headspace after 5 minutes of equilibrium between the sample and the headspace. Results: Samples added 0.10% oregano or sage had effective protection in the development of hexanal, compared to control samples. The development of hexanal was significantly higher in the control samples, 34 μg of hexanal/100 g of sample at the beginning and 280 µg/100 g sample at the end of refrigerated storage. Conclusion: Herbs were effective in controlling the development of hexanal. However, the oregano was more effective than sage in preventing the formation of hexanal in chicken meatballs pre-cooked. The level of hexanal in herbs at the end of the storage period was 5 μg hexanal/100 g sample for oregano and 23 µg hexanal/100 g sample for sage.

A Maria José de Aguiar Pino (in memoriam) por me transmitir paz e serenidade Aos meu irmãos Júnior e Ana Paula DEDICO Ao Luccas por todos os momentos OFEREÇO AGRADECIMENTOS À Deus; Aos meus pais, pelo amor, educação, estímulo e exemplos de vida; Aos meus irmãos Júnior e Ana Paula, pelo carinho; Ao Luccas G. Rodrigues Longo, pela compreensão, apoio, estímulo e dedicação constante em todos os momentos; À minha orientadora, Profa. Dra. Marisa A. B. Regitano d'Arce responsável pela minha formação científica e exemplo de profissional, meu eterno agradecimento, pela paciência, estímulo, apoio, confiança e amizade durante todos estes anos; À amiga Maria Fernanda de Almeida Prado, sempre disposta a ajudar, pelo auxilio técnico e pelos momentos de alegria em todo o decorrer deste trabalho; Ao Prof. Dr. José Fernando M. Mentem pela doação dos animais; À Dra. Aline Calil Racanicci pela amizade, sugestões e auxílio durante todo o trabalho; À FAPESP, pela concessão da bolsa de mestrado; Ao Prof. Severino Matias de Alencar e a técnica Ivani Moreno, pelo auxilio nas análises cromatográficas; À amiga Denise de Oliveira Biato, pela ajuda e amizade em todos estes anos; Às estagiárias Bruna Bonim e Mariana Marchesan, pelo auxílio na condução do experimento; Aos amigos Daniela Cordeiro e Eduardo Salan, pelo auxílio na v embalagem da matéria-prima; Aos professores Drs. Marília Oetterer, Carmem Contreras Castillo e Eduardo Vicente, pelas sugestões e auxílio nas correções; Aos amigos e companheiros de laboratório Aelson Brum, Selma Pacheco e Talita Benedetti, sempre dispostos a ajudar; À bibliotecária Beatriz Helena Giongo, pela correção deste trabalho; À Roberta Tereza Rizzo Benatto, pela amizade e pelo auxílio na formatação deste trabalho; À Dra. Juliana Giannotti, pela paciência e auxílio na análise estatística; Aos provadores do painel de análise sensorial; À todos os funcionários do Departamento de Agroindústria, Alimentos e Nutrição, que direta ou indiretamente colaboraram para a realização desta pesquisa, agradeço.