No abstract

Terrincho cheese is an uncooked, pressed cheese made from raw whole ovine milk from the "Churra da Terra Quente" breed. It requires a minimum ripening time of 30 d. A detailed evaluation of the effect of ripening time on the breakdown of the casein fractions, along with the formation of major breakdown products of casein hydrolysis, was monitored by HPLC to contribute to a more complete characterization of this product. In 30-d-old cheeses, only 20% of alpha(S1)-casein remained intact; the beta-casein fraction was more resistant to hydrolysis. The ripening time of Terrincho cheese can be predicted using 2 variables of normalized peak areas of alpha(S1)-casein and alpha(S1)-I peptide, and a constant; the estimation error is 2.5 d. The pH 4.3-insoluble fraction of Terrincho and cheeses manufactured with bovine milk and with ovine milk combined with 2 levels of bovine milk (10 and 20%) revealed different chromatographic and electrophoretic profiles, especially the alpha(S1)-casein fraction. Similar proteolysis progress was observed, particularly in the percentage of casein fraction degradation. However, using both analytical methods, the detection of 10% bovine milk at 30 d of ripening was no longer possible as result of alpha(S1)-casein hydrolysis. The discriminate analysis applied to HPLC data indicated that at 30 d of ripening, differences between the casein fractions of Terrincho cheese and mixture cheeses were mainly from beta1-casein content. The function thus obtained was able to correctly classify all the samples according to cheese type. Using the descriptive sensory profile, Terrincho cheese at 30 d of ripening could be distinguished from bovine and mixture cheeses owing to its higher fracturability and adhesiveness and lower elasticity and hardness, which correlated with its lower total casein content.

-5-Hydroxymethylfurfural (HMF) is considered to be an important building block for biorefineries and has a high potential for the production of chemicals and fuels. Production of HMF from glucose was studied using phosphoric acid as catalyst, in a water:acetone system with volume ratio of 1:2 and NaCl. An experimental design was applied to examine the influence of temperature, time and concentration of catalyst on the HMF yield. HMF yields of more than 50 % were obtained when using 200 °C, 8.4 min and 0.8% of catalyst. The temperature is the main factor influencing the HMF yield.

a b s t r a c tGoat milk cheese is highly appreciated since ancient times. However, besides being consumed close to its production date, according to the common practice, there is an increasing trend towards consuming goat milk cheese submitted to long ripening periods. Throughout this process, several chemical changes are expected, justifying the different properties presented by ripe cheese in comparison to fresh one. Accordingly, proximate composition, salt percentage, saponifiable matter, color parameters, pH and fatty acids were compared in cheese submitted to medium, long and extra-long ripening. The parameters showing significant changes among different ripening periods were effectively identified, highlighting fatty acids as the ones with highest variation. Actually, fatty acids profiles were successfully assayed as a chemical fingerprint of goat milk cheese submitted to different ripening periods. This result raised up the possibility of discriminating goat milk cheese ripening period using a single, fast and reliable chromatographic methodology.

Resumo: Com o objetivo de dar a conhecer a qualidade do leite cru de ovinos da área geográfica de produção do Queijo Terrincho DOP, desenvolveu-se este estudo numa queijaria em Vilas Boas, freguesia de Vila Flor. Foram recolhidas 70 amostras de leite cru de ovelha da raça Churra da Terra Quente (CTQ) e 138 amostras de leite cru de ovelha de "outras raças" ao longo de cinco meses (Fevereiro a Junho de 2012). As amostras foram submetidas a análises realizadas por um laboratório interprofissional acreditado (ALIP), onde os parâmetros analisados foram relativos à qualidade físico-química (gordura, proteína e ponto de congelação) e higiénica do leite (contagem de células somáticas). Estas determinações foram comparadas em função dos diferentes tipos de leite (CTQ e "outras raças"). Os resultados evidenciaram qualidade superior para a produção de queijo no leite da raça CTQ em comparação com o leite de "outras raças" sendo o primeiro mais rico em termos de gordura com um valor médio de 7,58% e 5,82% de teor proteico médio. O leite fornecido para a produção de Queijo Terrincho DOP é de qualidade aceitável, sendo o parâmetro da contagem das células somáticas destacado com valores um pouco mais elevados mas, mesmo assim, inferior a 1000 × 10 3 cel/mL, contrariamente ao que sucedeu no leite de "outras raças", que ultrapassou esse valor. Palavras-chave:Qualidade físico-química; qualidade higiénica; leite cru de ovelha; raça Churra da Terra Quente. Abstract:In order to assess the quality of raw sheep milk of the geographic region of production of the Terrincho cheese (PDO), this study was carried out in an artisanal cheese factory in Vilas Boas, a village from Vila Flor municipality. Over five months (from February to June of 2012), 70 samples of raw milk of Churra da Terra Quente (CTQ) sheep breed and 138 samples of raw sheep milk from "other breeds" were collected. The samples were submitted to physical and chemical (fat, protein and freezing point) and hygienic quality analysis (somatic cell count) by a qualified inter-professional laboratory (ALIP). These parameters were compared according to different milk types (CTQ and "other breeds"). The results demonstrated highest quality for cheese production of the CTQ sheep 1 Artigo em português europeu