The chemical and microbial characteristics as well as the flavor and aroma of Los Pedroches cheese made using aqueous extracts of Cynara cardunculus L. flowers were compared with those of cheeses manufactured with extracts of Cynara humilis L. throughout ripening. The two thistle species assayed were found to have no appreciable effect on the moisture, fat, protein, and NaCl contents of the cheese or on its water activity, flavor, and aroma; however, the use of C. humilis resulted in reduced lactic acid content (p < 0.001) and higher pH values (p < 0.05) relative to those of cheese specimens produced with C. cardunculus. The protein breakdown of the cheeses was assessed in terms of soluble nitrogen (SN), nonprotein nitrogen (NPN), and amino acid nitrogen (AAN). Proteolysis was more marked and rapid in cheese containing C. cardunculus as coagulant, the SN and NPN contents of which were significantly higher (p < 0. 01) than those of the cheese obtained with the species C. humilis; AAN contents were similar in both species of Cynara throughout ripening. Although total viable, coliform, and lactobacilli counts were similar in cheeses produced with both types of plant coagulant throughout ripening, enterobacteria and yeasts counts (p < 0.01) and molds counts (p < 0.05) were higher in cheese produced with C. humilis than in cheese obtained with C. cardunculus.

The aim of the present work was to study the sensorial characteristics of Los Pedroches cheese after freezing, monitoring the effects of the speed and time of frozen storage. Changes were observed in the hardness, creaminess and eyes of cheeses after 3‐months frozen storage. The paste hardened, becoming less creamy, and the number and size of the eyes decreased substantially. However, these attributes remained unchanged during storage periods of up to 9 months. Odor, flavor intensity, acidity and grainy were modified as a consequence of frozen storage. The speed of the freezing process only affected the grainy of the cheese; this was greater in slowly‐frozen cheeses.

BACKGROUND: Cheese-makers have traditionally kept vegetable coagulants refrigerated until use, even though little was known of their microbiological quality or coagulant activity during storage. This study aimed to assess the efficacy of lyophilisation, refrigerated storage and frozen storage of fresh vegetable extract as a means of standardising coagulant activity in terms of coagulation times, pH and microbiological quality.

Most chemical components and water activity of an the Los Pedroches' brand ewes' milk cheese were not altered by frozen storage. Lactic acid concentration and pH were significantly different (p Ͻ Ͻ Ͻ Ͻ Ͻ 0.05) in control cheeses and those kept in frozen storage for 3 and 6 months from those stored for 9 months. Proteolysis continued slowly during frozen storage, with significantly higher rates of non protein nitrogen and amino acid nitrogen (p Ͻ Ͻ Ͻ Ͻ Ͻ 0.05) present at the end of the storage period. Counts of microorganisms, except for enterococci, tended to decrease during frozen storage. Freezing rates did not affect the chemical and microbiological characteristics studied.

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