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Manchego cheese can be manufactured from raw or pasteurized ewes' milk. An automatic purge and trap apparatus, coupled to a GC-MS was used to isolate, identify and compare the relative amounts of the volatile components of raw and pasteurized Manchego cheese during ripening. The majority of volatile compounds were more abundant in raw milk (RM) cheeses than in pasteurized milk (PM) cheeses. Alcohols and esters predominated in the profile of RM Manchego cheese, while methyl-ketones and 2,3-butanedione were quantitatively important in PM cheeses. Branched chain alcohols were much more abundant in RM cheeses. The discriminant analysis separated 100% samples into RM or PM cheeses by using only 16 volatile compounds. Aroma intensity was correlated with esters, branched chain aldehydes and branched chain alcohols in RM cheeses, and with esters, branched chain aldehydes, 2-methyl ketones and 2-alkanols in PM cheeses. Diacetyl was positively correlated with the aroma attribute ‘toasted’ and negatively correlated with aroma quality in PM cheeses.

-La Serena cheese is a soft to semi-soft Spanish variety manufactured from Merino ewe raw milk coagulated with an extract of Cynara cardunculus. In the present work a purge and trap extraction procedure coupled to gas chromatography -mass spectrometry was used to study the volatile fraction evolution during ripening of La Serena cheese. A total of 112 compounds were identified. Alcohols were quantitatively the main chemical family in the volatile fraction, increasing significantly during ripening. Ethanol, 1-propanol, 2-propenol, 2-propanol, 2-butanol, 2-pentanol and the branched chain 2-methyl-1-propanol and 3-methyl-1-butanol, were abundant at the end of ripening. Esters, especially ethyl esters of acetic, butanoic, hexanoic and octanoic acids and 3-methyl-1-butanol acetate, were found at high levels in the headspace of La Serena cheese. Concentrations of most esters increased dramatically during ripening, and, given their low perception thresholds, may be considered as key constituents of the aroma of this cheese variety. The principal component analysis of sensory attributes and volatile compounds extracted 3 functions. Linear aldehydes and alcohols, 2-alkanols, branched-chain alcohols, 2-methyl-ketones, alkanes, terpenes and esters other than ethyl esters correlated positively with function 1 (25.8% of the variance explained). Odour and aroma quality, along with the sensory attributes lactic, fruits-flowers, and clean cheese flavour, and the volatiles ethanol and ethyl esters, had a high correlation coefficient with function 2 (14.8% of the variance explained). 2-Butanone and the sensory attributes fishy and putrid had a negative correlation coefficient with this function. Odour and aroma intensity, along with the sensory attributes animal, pungent and fishy, and the volatile compounds branched chain aldehydes, n-alkanols, 2-butanol and esters, were positively correlated with function 3 (11.0% of the variance explained). Terpenes had a negative correlation coefficient with this function. Résumé -Évolution des composés volatils dans le fromage La Serena pendant l'affinage. Corrélation avec les caractéristiques sensorielles. La Serena est un fromage à pâte molle ou demi-dure fabriqué à partir du lait cru de brebis Merino coagulé avec un extrait de Cynara cardunculus. Pour étu-dier la fraction volatile pendant l'affinage du fromage La Serena, un dispositif d'extraction par espace de tête dynamique « purge and trap » couplé à un appareil de CG-SM a été utilisé. Les alcools étaient quantitativement la principale famille chimique dans la fraction volatile, et augmentaient significativement au cours de l'affinage. L'éthanol, le 1-propanol, le 2-propenol, le 2-propanol, le 2-butanol, le 2-pentanol et les alcools ramifiés 2-méthyl-1-propanol et 3-méthyl-1-butanol étaient très abondants en fin d'affinage. Des esters, principalement des esters éthyliques des acides acétique, butanoïque, hexanoïque et octanoïque, ont été trouvés à des niveaux assez élevés dans la fraction volatile du fromage La Serena. Les con...

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Benzoic acid is an aromatic carboxylic acid naturally present in plant and animal tissues, which can also be produced by microorganisms. Benzoic acid and a wide range of derivatives and related benzenic compounds, such as salts, alkyl esters, parabens, benzyl alcohol, benzaldehyde, and benzoyl peroxide, are commonly used as antibacterial and antifungal preservatives and as flavoring agents in food, cosmetic, hygiene, and pharmaceutical products. As a result of their widespread occurrence, production, and uses, these compounds are largely distributed in the environment and found in water, soil, and air. Consequently, human exposure to them can be high, common, and lengthy. This review is mainly focused on the presence and use of benzoic acid in foods but it also covers the occurrence, uses, human exposure, metabolism, toxicology, analytical methods for detection, and legal limits for benzoic acid and its derivatives. Their controversial effects and potential public health concerns are discussed.

Lactococcus lactis subsp. lactis INIA 415, a strain harboring the structural genes of bacteriocins nisin Z and lacticin 481, was used as adjunct culture in the manufacture of Hispánico cheese with a mesophilic starter and a thermophilic starter of high aminopeptidase activity. Addition of the bacteriocin producer promoted early lysis of mesophilic and thermophilic starter bacteria. Extracellular aminopeptidase activity in 7-day-old cheese made using mesophilic and thermophilic starters plus bacteriocin producer was 3.0-fold the level reached in cheese made without the bacteriocin producer. Proteolysis in cheese made with mesophilic and thermophilic starters plus bacteriocin-producing adjunct culture after 25 days of ripening was 1.5-fold the level reached in cheese made without the bacteriocin producer, and the level of total free amino acids was 2.9-fold the level found in cheese made without the bacteriocin producer. Cheese made with mesophilic and thermophilic starters plus bacteriocin producer received the highest scores for flavor quality and flavor intensity and reached in 25 days the flavor intensity score of a 75-day-old cheese made without the bacteriocin producer.

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