Freezing/thawing as an accelerating process of wet- and dry-aged Nellore beef.

This study aimed to evaluate the use of freezing/thawing as a way of accelerating the aging processes of beef from Nellore animals. Non-frozen (NF) or freezing/thawing (FT) strip loins were aged (for 14 and 28 days) using two systems: bone-in dry-aging (DA); boneless wet-aging (WA). FT-treated samples had greater weight losses (P < 0.05) during aging than NF-treated samples, especially using the DA process. However, the weight loss of the FT 14-days DA beef samples was comparable to that of NF 28-days DA. FT beef had lower fragmentation index and shear force values (P < 0.05), as well as its maximum sensorial tenderness was achieved earlier (P < 0.05) than the NF counterpart. With 28 days of aging, DA beef showed higher (P < 0.05) tenderness and juiciness scores and lower lightness values than WA beef. The FT process decreased the reducing capacity of meat samples, generating more metmyoglobin and lower amounts of chroma than NF. The expected volatile profile of DA beef was achieved faster in FT-treated samples, but the freezing treatments did not compromise the microbial count for either aging system. Our findings indicate that accelerated DA by the FT process could improve the palatability of Nellore beef, allowing the desired tenderness and flavor profile to be achieved in a shorter time, without increasing costs with weight losses or adversely affecting physicochemical, chemical, and microbial characteristics.

Effect of freezing/irradiation/thawing processes and subsequent aging on tenderness, color, and oxidative properties of beef.

This study evaluated the use of gamma irradiation (3, 6 and 9 kGy) in frozen vacuum-packed beef and subsequent thawing and aging for up to 14 days. The effects on tenderness, color, and oxidative properties were determined and compared to non-irradiated controls for frozen/thawed and chilled vacuum-packed beef. The combined irradiation and freezing/thawing processes increased total exudate loss and reduced the meat water-holding capacity, regardless of the dose used. Myofibrillar fragmentation was favored by the freezing/thawing processes and negatively affected by irradiation. Lower shear force values were observed in the non-irradiated frozen/thawed samples. Frozen samples irradiated at 9 kGy had a higher percentage of soluble collagen, lipid peroxidation, and a more reddish color tone. The meat reducing capacity and oxygen consumption were reduced by freezing and further by irradiation, which also included accumulation of metmyoglobin. It was concluded that irradiation of frozen meat and its subsequent thawing and aging does not confer any additional advantages for beef technological quality.

Combined effects of gamma irradiation and aging on tenderness and quality of beef from Nellore cattle.

Combined effects of gamma irradiation (0, 3, 6 and 9 kGy) and aging (1 and 14 days) on quality attributes of vacuum-packaged beef from Nellore cattle were evaluated. The meat water holding capacity was affected by irradiation, increasing (p < 0.05) purge and cooking loss regardless of the dose used. Irradiation negatively affected myofibrillar fragmentation, but samples irradiated at 9 kGy had (p < 0.05) higher soluble collagen and lower shear force values. The meat metmyoglobin reducing activity was reduced (p < 0.05) by the irradiation process, inducing the metmyoglobin accumulation with increasing dose applied. Samples irradiated at 9 kGy presented (p < 0.05) higher lipid oxidation and lower oxymyoglobin proportion and color redness and chroma values. It was concluded that irradiation at 9 kGy combined with aging can be used as an effective tool for improving the tenderness of Nellore beef, but resulted in a discoloration of the beef.

Protein concentrates obtained from pig by-products using pH-shifting technique: a preliminary study / Concentrados proteicos obtidos de subprodutos suínos pela técnica de mudança do pH: um estudo preliminar

ABSTRACT: This study aimed to investigate the extraction and characterization of protein concentrates from pig by-products (heart, liver and kidneys) using the pH-shifting technique. From the solubility profiles (pH 2 to 12), the protein extraction was performed at alkaline pH (10.0 to 11.5), obtaining two fractions: soluble (SC) and insoluble (IC). Higher protein content (71 to 77%) and extractability (214 to 459 mg/g) were observed in heart and liver concentrates; whereas, for water holding capacity (WHC) the highest values (4.20 to 4.54 g water/g protein) were for the heart (SC) and kidney (SC and IC) concentrates. All concentrates had high emulsion stability and higher WHC than commercial protein extenders (whey and soybean). The concentrates obtained from the soluble fraction were redder (higher a* values and lower h values) and darker (lower L* values) than insoluble fraction, especially heart and liver concentrates. Use of concentrates in sausage production slightly altered the color chroma (C*) of samples. It was concluded that the pig by-products protein concentrates had great potential of use as extenders in sausage production.

RESUMO: Objetivou-se investigar a extração e caracterização de concentrados proteicos obtidos de miúdos suínos (coração, fígado e rins) pela técnica da solubilização isoelétrica. A partir das curvas de solubilidade (pH 2 a 12), a extração proteica foi realizada em pH alcalino (10,0 a 11,5), obtendo-se concentrados de duas frações: solúvel (CS) e insolúvel (CI). Maiores teores de proteína (71 a 77%) e solubilidade proteica (214 a 459 mg/g) foram observados nos concentrados do coração e do fígado, enquanto para a capacidade de reter água (CRA) os maiores valores (4,20 a 4,54 g água/g proteína) foram para os concentrados de coração (CS) e rins (CS e CI). Todos os concentrados apresentaram alta capacidade estabilizante e maior CRA do que extensores proteicos comerciais (soro de leite e soja). Os concentrados obtidos da fração solúvel eram mais vermelhos (maiores valores de a* e menores de h) e mais escuros (baixos valores de L*) do que os insolúveis, especialmente os concentrados de coração e fígado. O uso dos concentrados na elaboração de salsichas alterou ligeiramente a saturação (C*) da cor das amostras. Concluiu-se que os concentrados de subprodutos suínos apresentam grande potencial de uso como extensores na elaboração de salsichas.

Comparison of different criteria used to categorize technological quality of pork / Comparação de diferentes critérios utilizados para classificar a qualidade tecnológica da carne suína

ABSTRACT: Pork may be classified into quality categories according to its color, texture and exudation, though no international consensus criterion has been reached yet. Thus, the aim of the present paper was to examine the relation between important meat quality traits, evaluating pork quality classification of a same data by different criteria proposed in the literature. In 60 pork loins (Longissimus thoracis muscle), initial pH (pH45min) and R-value were evaluated after 45min post mortem between the 9th and 10th ribs, and ultimate pH (pH24h), objective color and water-holding capacity were evaluated 24h post mortem in two 2.54cm thick steaks cut between the 9th and 11th ribs to be classified into PSE (pale, soft and exudative), RSE (reddish-pink, soft and exudative), RFN (reddish-pink, firm and non-exudative) or DFD (dark, firm and dry) quality. Frequency distributions of quality categories differed (P<0.001) among criteria, which resulted in large variations: 3 to 68% PSE; 0 to 73% RSE; 5 to 68% RFN; 0 to 22% DFD; and 0 to 33% unclassified samples. A same sample may be classified into different quality categories according to the criterion utilized, which results in large variations in frequency distributions and also in quality attributes. Therefore, the classification of pork quality depends on the adopted criterion, which indicated the need for international standardization, so that pork quality can be determined efficiently and effectively.

RESUMO: A carne suína pode ser classificada em categorias de qualidade de acordo com sua cor, textura e exsudação, embora ainda não exista um critério internacional consensual. Desse modo, o objetivo do presente artigo foi verificar a relação entre importantes características de qualidade de carne, avaliando a classificação da qualidade da carne suína de um mesmo banco de dados por diferentes critérios propostos na literatura. Em 60 lombos (músculo Longissimus thoracis), pH inicial (pH45min) e Valor R, foram avaliados 45 minutos post mortem entre a 9a e a 10a costelas, e pH final (pH24h), cor objetiva e capacidade de retenção de água foram avaliados 24 horas post mortem, em dois bifes, com 2,54cm de espessura, cortados, entre a 9a e a 11a costelas, para serem classificados como PSE (pálida, flácida e exsudativa), RSE (vermelho-rosada, flácida e exsudativa), RFN (vermelho-rosada, firme e não-exsudativa) ou DFD (escura, firme e seca). As distribuições de frequência das categorias de qualidade diferiram (P<0,001) entre os critérios, resultando em grandes variações: 3 a 68% PSE; 0 a 73% RSE; 5 a 68% RFN; 0 a 22% DFD; e 0 a 33% de amostras não classificadas. Uma mesma amostra pode ser classificada em diferentes categorias de qualidade, de acordo com o critério utilizado, o que resulta em grandes variações nas distribuições de frequência e também nos atributos de qualidade. Portanto, a classificação da qualidade da carne suína é dependente do critério adotado, evidenciando a necessidade de uma padronização internacional para a identificação eficiente e eficaz da qualidade da carne suína.