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Determinação dos teores de gordura, humidade e proteína em carne de bovino dos Açores : contributo para a calibração do espectrofotómetro de infravermelhos próximo (NIR) e avaliação do potencial de diferentes peças da carcaça para elaboração de hambúrgueres
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Abstract(s)
A empresa “Quinta dos Açores”, procurando rentabilizar e valorizar os seus produtos, e na impossibilidade de comercializar certos produtos processados com o selo de “Carne dos Açores-IGP”, pretendeu criar uma linha premium de hambúrgueres com a marca Açores. Foi proposto pela empresa a criação de um hambúrguer com 20g de gordura/100g produto, utilizando peças de 2ª e 3ª categoria (dianteiros e abas) de carcaças de bovinos e animais certificados IGP.
Este trabalho teve como objetivo conhecer os teores de gordura, humidade e proteína das diferentes peças da carcaça utilizadas, para que se pudesse avaliar quais as peças da carcaça mais adequadas para a obtenção de um hambúrguer com um teor de gordura de 20g/100g. Foi também objetivo do presente trabalho a calibração do espectrofotómetro de infravermelho próximo (NIR) da Faculdade Ciências Agrárias e do Ambiente da Universidade dos Açores, contribuindo para quantificar a humidade, gordura e proteína da carne de bovino.
Foi utilizado e analisado um total de 66 amostras de carne (conjuntos da mesma peça, picados e hambúrgueres): 6 de mistura de abas, 5 de aba grossa, 4 de aba das costelas, 5 de acém comprido, 2 de peito, 6 de cachaço, 5 de chambão de mão, 10 picados de carne com gordura adicionada e por fim 23 hambúrgueres gourmet. Os métodos utilizados foram a secagem em estufa na determinação da humidade, o método de Kjeldahl na determinação da proteína e o método gravimétrico (extração a frio com solventes e pré-tratamento com hidrólise ácida) para a determinação do teor de gordura.
Os valores médios da gordura das diferentes peças de carne variaram entre 2,3 e 18,3g/100g de carne. A aba das costelas e a aba grossa foram as peças que apresentaram um teor de gordura que mais se aproximou do valor de 20g/100g para a utilização no hambúrguer. Observou-se ainda uma elevada heterogeneidade no conteúdo em gordura de algumas amostras, refletida pelo elevado valor do coeficiente de variação (>100%). Na calibração do aparelho NIR foram obtidos os coeficientes de determinação múltipla (R²) de 0,87 para o teor de gordura, 0,80 para a proteína e 0,72 para a humidade. Desta forma concluiu-se que a calibração do NIR poderá dar uma boa estimativa dos teores em humidade, gordura e proteína de carne bovina crua.
Os resultados do presente estudo permitem concluir que as peças de 2ª e 3ª categoria (dianteiros e abas) de carcaças de bovinos IGP dos Açores como as utilizadas neste trabalho, não permitem cumprir o parâmetro inicialmente estabelecido e sugere-se a continuação da calibração do NIR de forma a melhorar a fiabilidade do método para avaliação da composição química da carne de bovino.
ABSTRACT: The “Quinta dos Açores” company, in search for innovation and valuation of its products, and facing the impossibility of marketing certain processed products with the “Carne dos Açores-IGP” designation of origin, came up with the challenge for the creation of a premium line of Azores branded hamburgers. It was proposed by the company the creation of a hamburger composed of 20g of fat/100g of fresh product, using 2nd and 3rd category (from fore quarters and flaps) cuts of beef carcasses from PGI certified animals. The first goal of this project was to determine the fat, humidity and protein contents of the many carcass cuts to be used, so that an evaluation of such carcasses was possible in order to select the ideal cuts that would be used for the premium hamburger with 20g fat/100g row product. Another objective of this study was to calibrate the infrared spectrophotometer (NIR) of the Faculty of Agrarian and Environmental Sciences of the Azores University, concerning the evaluation of the humidity, fat and protein content of beef. Sixty six beef samples were used and analyzed (sets from the same piece, chopped meat and hamburgers): 6 rib mix, 5 flanks, 4 plate ribs, 5 chuck and rib eye, 2 brisket, 6 necks, 5 fore shanks, 10 minced meat minced and finally 23 gourmet hamburgers. The utilized methods were kiln drying to determine moisture, the Kjeldahl method to determine the protein and the gravimetric method (cold extraction with solvents and pre-treatment with acid hydrolysis) to determine the fat contents. The mean fat values of the different beef cuts were between 2,3 and 18,3g/100g of fresh product. The plate ribs and the flanks were the cuts which presented fat contents that most closely matched the value of 20g/100g for the usage in the hamburger. A very high fat variability was also observed in some samples, reflected by the high value of the coefficient of variation (>100%). In the calibration of the NIR apparatus, multiple determination coefficients (R²) of 0.87, 0.80 and 0.72 were obtained for fat, protein and moisture, respectively. Therefore, it was concluded that the NIR calibration would give a good estimate of the moisture, protein and fat contents of raw beef meat. It was concluded from this study that the 2nd and 3rd category cuts from the front quarters and flaps of “the Azorean PGI beef” carcasses like the ones used on this work, do not meet the requirements initially established for the making of a premium hamburger. Further data added in NIR calibration is suggested to improve the reliability of the method for the evaluation of chemical composition of beef.
ABSTRACT: The “Quinta dos Açores” company, in search for innovation and valuation of its products, and facing the impossibility of marketing certain processed products with the “Carne dos Açores-IGP” designation of origin, came up with the challenge for the creation of a premium line of Azores branded hamburgers. It was proposed by the company the creation of a hamburger composed of 20g of fat/100g of fresh product, using 2nd and 3rd category (from fore quarters and flaps) cuts of beef carcasses from PGI certified animals. The first goal of this project was to determine the fat, humidity and protein contents of the many carcass cuts to be used, so that an evaluation of such carcasses was possible in order to select the ideal cuts that would be used for the premium hamburger with 20g fat/100g row product. Another objective of this study was to calibrate the infrared spectrophotometer (NIR) of the Faculty of Agrarian and Environmental Sciences of the Azores University, concerning the evaluation of the humidity, fat and protein content of beef. Sixty six beef samples were used and analyzed (sets from the same piece, chopped meat and hamburgers): 6 rib mix, 5 flanks, 4 plate ribs, 5 chuck and rib eye, 2 brisket, 6 necks, 5 fore shanks, 10 minced meat minced and finally 23 gourmet hamburgers. The utilized methods were kiln drying to determine moisture, the Kjeldahl method to determine the protein and the gravimetric method (cold extraction with solvents and pre-treatment with acid hydrolysis) to determine the fat contents. The mean fat values of the different beef cuts were between 2,3 and 18,3g/100g of fresh product. The plate ribs and the flanks were the cuts which presented fat contents that most closely matched the value of 20g/100g for the usage in the hamburger. A very high fat variability was also observed in some samples, reflected by the high value of the coefficient of variation (>100%). In the calibration of the NIR apparatus, multiple determination coefficients (R²) of 0.87, 0.80 and 0.72 were obtained for fat, protein and moisture, respectively. Therefore, it was concluded that the NIR calibration would give a good estimate of the moisture, protein and fat contents of raw beef meat. It was concluded from this study that the 2nd and 3rd category cuts from the front quarters and flaps of “the Azorean PGI beef” carcasses like the ones used on this work, do not meet the requirements initially established for the making of a premium hamburger. Further data added in NIR calibration is suggested to improve the reliability of the method for the evaluation of chemical composition of beef.
Description
Dissertação de Mestrado, Tecnologia e Segurança Alimentar, 18 de fevereiro de 2020.
Keywords
Ácidos Gordos Polinsaturados Bovinicultura Carne de Bovino Gordura Animal Indústria Alimentar
Citation
Melo, Tiago Manuel Medeiros Vieira. "Determinação dos teores de gordura, humidade e proteína em carne de bovino dos Açores: contributo para a calibração do espectrofotómetro de infravermelhos próximo (NIR) e avaliação do potencial de diferentes peças da carcaça para elaboração de hambúrgueres". 2020. 54 p.. (Dissertação de Mestrado em Tecnologia e Segurança Alimentar). Angra do Heroísmo: Universidade dos Açores, 2019. [Consult. Dia Mês Ano]. Disponível em www:<http://hdl.handle.net/10400.3/5956>.