A.I. Ordóñez

Formation of biogenic amines in Idiazabal ewe's-milk cheese: effect of ripening, pasteurization, and starter

The importance of biogenic amines stems from their toxicity and their potential as a cause of food poisoning. After fish, cheese has been the foodstuff most often responsible for cases of food poisoning caused by ingestion of biogenic amines. Changes in biogenic amine (histamine, tyramine, putrescine, cadaverine, tryptamine, isopentylamine, spermidine, and phenylethylamine) content during the ripening of a cheese made from raw ewes milk were studied, together with the effects of pasteurization and a commonly used commercial starter and indigenous starter cultures. Biogenic amines were determined by high-pressure liquid chromatography following extraction from the cheese and derivatization with dansyl chloride. Levels of histamine, potentially the most toxic amine, in the semihard Idiazábal cheese were very low. Tyramine, putrescine, and cadaverine were the main amines present in this type of cheese. Levels of those amines increased during ripening. Pasteurization of the milk brought about a reduction in the biogenic amine content of the ripened cheese, irrespective of the starter culture employed. The indigenous starter cultures considered in this study produced higher levels of histamine and cadaverine and lower levels of tyramine and putrescine than the commercial starter culture tested.

Evolution of free amino acids during Idiazábal cheese ripening

Abstract As a contribution to knowledge of ripening ewes cheese, the evolution of free amino acids was studied over a year of the ripening period by reversed phase high performance liquid chromatography (RP-HPLC). Total free amino acid content during Idiazabal cheese ripening varied between 140 mg/100 g dry matter the first day and 1500 mg/100 g dry matter at one year. The major amino acids were: glutamic acid, leucine, valine, phenylalanine, lysine and alanine which approximately accounted for 50% of the total free amino acid content, probably indicating the preferential cleavage of peptide bonds by the proteolytic agents in the cheese. Non-protein amino acids such as ornithine, citrulline or γ-aminobutyric acid were also found in proportions near to 9% of the total free amino acids. Amino acids such as arginine, which is responsible for unpleasant tastes, or γ-aminobutyric acid, which is usually detected in low quality cheese, are present in very low concentrations in Idiazabal cheese.

Validation of capillary electrophoresis in the analysis of ewe's milk casein

Recent investigations have shown that capillary electrophoresis (CE) can be an alternative to other techniques such as polyacrylamide gel electrophoresis (PAGE) or sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the qualitative analysis and separation of the different casein fractions in cows and ewes milk. However, past work has not yet clarified whether that method can achieve good quantifications. The present study has used a commercial whole ovine casein standard and a mixture of the standard and whole casein extracted from ewes milk cheese to test the reliability of the technique. The results show that CE was able to quantify the ewes milk caseins. The areas under four of the most representative peaks on the electrophoretogram for two alpha and two beta-caseins (designated alpha-casein1CE, alpha-casein2CE, beta-casein1CE, and beta-casein2CE in order of elution) were used to validate the method. In relation to linearity, coefficient of determination (r2) values greater than 99% were obtained for the regressions of each of the caseins. Moreover, each casein yielded response factors with a relative standard deviation (R.S.D.) of less than or equal to 5. The coefficients obtained in the day-to-day reproducibility analysis were higher than those for the same-day repeatability, but all the values were within acceptable limits. In the study of accuracy, the percentage recovery rates for the alpha-casein fractions were higher than those for the beta-casein fractions, hence quantification of the latter using this technique would appear to be more accurate under the conditions employed.

Effect of ewe's-milk pasteurization on the free amino acids in Idiazábal cheese

Abstract This study compared the use of raw and pasteurized milk in the manufacture of Idiazabal ewes-milk cheese. Two indigenous starters, A and B were tested in an attempt to find a starter culture potentially capable of developing the typical characteristics of Idiazabal cheese traditionally made from raw milk while using pasteurized milk. The nitrogen fractions and free amino acids were analysed over the ripening period. Pasteurization caused a considerable decrease in amino acid release in the cheese during ripening as reflected by the levels of non-protein–nitrogen and total free amino acids with starter A, but not when starter B was used. Multivariate analysis confirmed increases in asparagine, serine, and taurine and decreases in aspartic acid and glycine with pasteurization, irrespective of the starter used. The changes recorded in the levels of certain amino acids may be directly or indirectly responsible for the atypical sensory characteristics of the cheeses. Pasteurization of the milk for the manufacture of Idiazabal cheese is not recommended with either of the two starters tested.

Note. Effect of brining time on proteolytic changes in Idiazábal cheese during ripening / Nota. Cambios proteolíticos durante la maduración del queso Idiazábal por efecto del tiempo en salmuera

Idiazábal cheeses were made employing brining times of 12 h (batch A) and 36 h (batch B). Proteolytic changes in both batches were examined over 270 d of ripening; proteolysis was low in both batches, but lower in batch B than in batch A. Electrophoretic analysis revealed incom plete breakdown of αs and β-caseins at the end of the ripening period, particularly in batch B. The proportion of soluble nitrogen as a percentage of total nitrogen was 17.55% in batch B and 19.48% in batch A, while the proportion of non-protein nitrogen was 11.78% in batch B and 15.16% in batch A. The proportion of non-protein nitrogen as a percentage of soluble nitrogen was 67.17% in batch B and 77.88% in batch A. The free amino acids, the smallest non-protein nitrogen frac tion, attained values of 1203 mg/100 g of dry matter in batch B and 1902 mg/100 g of dry matter in batch A. After 60 d of ripening, the main free amino acids were glutamic acid, valine, leucine, lysine, and phenylalanine in both batches, although levels were higher in the batch with the shorter brining time. There was no clear trend in the non-protein-forming amino acids with either ripening time or brining time.

Improvement of the Functional and Healthy Properties of Meat Products

Abstract Over the last decade, the consumer demands meat and meat products with enhanced composition. Reductions in contents of fat, cholesterol, salt and nitrite, as well as improvement in fatty acid profile and incorporation of bioactive compounds are increasing worldwide. The food industry basically has two strategies to provide meat products adapted to such demand, on the one hand, production of raw material with healthy ingredients, and on the other, reformulation of the finished products. For the first option, modification of diet and supplementation would be an effective approach to enhance animal breeding, carcass yield, and meat quality. For the second option, novel processing methods are based in redefinition of meat products replacing animal fat with vegetable and fish oils and adding ingredients as dietary fibers, vitamins, minerals, and others. The latter ones included polyphenols, natural antioxidants that, in addition to its functional properties, have biological activities to provide beneficial effects for the human health. However, changes in formulation have had an impact on the quality and palatability of the new meat products that should be taken into consideration. Elaboration of cooked meat products with selected nutrients and ingredients (polyunsaturated fatty acids, soluble fiber, polyphenols, etc.) would have a positive impact on consumers’ health and likely affect product choice by the consumer. Moreover, the introduction of the modified meat product improves the nutritional status of the subjects with special needs and equalizes their population characteristics and leads to health benefits for the elderly population. This chapter provides an updated and critical review based in the experience of authors on meat products (beef, pig, foal, and lamb) and consumers.