Microbial changes and aroma profile of nitrate reduced dry sausages during vacuum storage.

Slow fermented sausages with reduced ingoing amounts of sodium nitrate (control, 15% and 25% reduction) were stored under vacuum up to three months. Changes in microbiology, chemical parameters and volatile compounds were studied. Residual nitrate was not affected by vacuum storage and its reduction resulted in a reduction of sausage redness. General microbial counts decreased during vacuum storage, though nitrate reduction increased the growth of total mesophilic bacteria and Gram positive cocci. Long storage time and 25% nitrate reduction affected microbial activity and sausage aroma profile. Short vacuum storage times and moderate nitrate reduction (15%) were related to compounds producing pleasant odours (3-hydroxy-2-butanone, ethyl octanoate, ethyl-3-methylbutanoate and 2,3-pentanedione) and cheesy/buttery odour (2,3-butanedione and ethyl-2-hydroxypropanoate). In contrast, 25% nitrate reduction increased compounds like heptanal (green, unpleasant odour) and those related to unpleasant odours, methanethiol (rotten odour) and methional (cooked potato).

Nitrate reduction in the fermentation process of salt reduced dry sausages: Impact on microbial and physicochemical parameters and aroma profile.

Slow fermented sausages with reduced ingoing amounts of sodium nitrate were manufactured: control (250 ppm), 15% (212.5 ppm) and 25% (187.5 ppm) reduction. The effect of nitrate reduction on microbiology and chemical parameters, volatile compounds and aroma production was studied. Parameters like, pH, aw and colour decreased during ripening, without being affected by nitrate reduction. Lipid oxidation increased during ripening and it was higher in control sausages due to fat content. Residual nitrite was below the detection limit during the whole process and residual nitrate decreased during ripening, with higher reduction in RN25 sausages. Lactic acid bacteria, total mesophilic bacteria and yeasts and moulds increased during ripening but Gram positive cocci decreased. Microbial counts from nitrate reduced sausages at the end of the manufacturing process were not statistically different from the control sausages with nitrate. Regarding volatile compounds formation, compounds derived from amino acid degradation were increased by nitrate reduction. Aroma compounds derived from amino acid degradation and responsible for strong odours, dimethyl disulphide (toasted, garlic) and methional (cooked potato) and, to a lesser extent, compounds derived from esterase activity producing fruity odours (ethyl acetate, ethyl butanoate, ethyl­2­hydroxypropanoate, ethyl­2­methylbutanoate and ethyl­3­methylbutanoate) and several compounds from carbohydrate fermentation acetic acid (vinegar odour) and 2-butanone (fruity) were related to the high nitrate reduction (25%). Despite nitrate reduction up to 25% produced minor effect on microbial growth, their metabolism is regulated by nitrate content and therefore by nitrite generation affecting the production of key aroma compounds that alter the sausage aroma profile.

Screening of Debaryomyces hansenii Strains for Flavor Production under a Reduced Concentration of Nitrifying Preservatives Used in Meat Products.

A total of 15 Debaryomyces hansenii strains from different food origins were genetically characterized and tested on a culture medium resembling the composition of fermented sausages but different concentrations of nitrifying preservatives. Genetic typing of the D. hansenii strains revealed two levels of discrimination: isolation source or strain specific. Different abilities to proliferate on culture media containing different concentrations of nitrate and nitrite, as sole nitrogen sources and in the presence of amino acids, were observed within D. hansenii strains. Overall metabolism of amino acids and generation of aroma compounds were related to the strain origin of isolation. The best producers of branched aldehydes and ethyl ester compounds were strains isolated from pork sausages. Strains from cheese and llama sausages were good producers of ester compounds and branched alcohols, while vegetable strains produced mainly acid compounds. Nitrate and nitrite reduction affected in different ways the production of volatiles by D. hansenii.

[Risk of glucose metabolism changes in spouses of Mexican patients with type 2 diabetes]. / Riesgo de alteración en el metabolismo de la glucosa en cónyuges de pacientes mexicanos con diabetes mellitus tipo 2.

BACKGROUND AND OBJECTIVE: To determine whether in the Mexican population the spouses of patients with type 2 diabetes mellitus (DM2) have an increased risk of any degree of glucose intolerance compared with spouses of subjects without diabetes. SUBJECTS AND METHOD: An analytical cross-sectional study was made in the Family Medicine Unit number 62 of the Mexican Institute of Social Security, located in the State of México. A random sample of 87 spouses of patients with DM2 (group ED) was compared with 87 spouses of subjects with a normal glucose tolerance (group ENOD). Risk factors for DM2 were investigated; spouses in both groups underwent oral glucose tolerance test, and total cholesterol, triglycerides, blood pressure, body mass index and waist circumference were measured. The frequency of impaired fasting glucose, impaired glucose tolerance and DM2 were compared in both groups and the odds ratio was calculated. RESULTS: In the group ED there were 38 (43.7%) subjects with any degree of glucose intolerance vs. 23 (26.4%) in the ENOD group -odds ratio = 2.16 (95% confidence interval, 1.14-4.08) in the bivariate analysis, and odds ratio = 2.37 (95% confidence interval, 1.14-4.91) in the logistic regression-. In the group ED a higher systolic blood pressure was observed (P=.02). There were no significant differences in age, sex, body mass index, waist circumference, total cholesterol, triglycerides and diastolic blood pressure. The frequency of risk factors for diabetes was similar in both groups. CONCLUSIONS: In the Mexican population, the spouses of subjects with DM2 have a higher risk of any alteration in the glucose tolerance than spouses of subjects with a normal glucose metabolism.

Riesgo de alteración en el metabolismo de la glucosa en cónyuges de pacientes mexicanos con diabetes mellitus tipo 2 / Risk of disorders in the glucose metabolism in spouses of Mexican patients with type 2 diabetes

FUNDAMENTO Y OBJETIVO: Determinar si en la población mexicana los cónyuges de pacientes condiabetes mellitus tipo 2 (DM2) tienen mayor riesgo de alteración en el metabolismo de la glucosa(AMG) que los cónyuges de personas sin diabetes.SUJETOS Y MÉTODO: Se ha realizado un estudio transversal analítico en la Unidad de Medicina Familiarnúmero 62 del Instituto Mexicano del Seguro Social, ubicada en el Estado de México. Secomparó una muestra aleatoria de 87 esposos de pacientes con DM2 (grupo ED), con 87 espososde personas con metabolismo normal de la glucosa (grupo ENOD). En ambos grupos se investigaronlos factores de riesgo para diabetes, se realizó una curva de tolerancia a la glucosaoral y se midieron el colesterol total, triglicéridos, presión arterial, índice de masa corporal ycircunferencia de la cintura. Se comparó la frecuencia de AMG (alteración de la glucosa enayunas, intolerancia a la glucosa y diabetes mellitus) y se calculó la odds ratio.RESULTADOS: En el grupo ED hubo 38 personas (43,7%) con alguna AMG, frente a 23 (26,4%)en el grupo ENOD, con una odds ratio de 2,16 (intervalo de confianza del 95%, 1,14-4,08) enel análisis bivariado y de 2,37 (intervalo de confianza del 95%, 1,14-4,91) en la regresión logística.En el grupo ED se observó una mayor presión arterial sistólica (p = 0,02). No hubo diferenciassignificativas en cuanto a la edad, sexo, índice de masa corporal, circunferencia de lacintura, colesterol total, triglicéridos y presión arterial diastólica. La frecuencia de factores deriesgo para diabetes fue similar en ambos grupos.CONCLUSIONES: En población mexicana, los cónyuges de pacientes con DM2 tienen mayor riesgode AMG que los cónyuges de personas con metabolismo normal de la glucosa

BACKGROUND AND OBJECTIVE: To determine whether in the Mexican population the spouses of patientswith type 2 diabetes mellitus (DM2) have an increased risk of any degree of glucose intolerancecompared with spouses of subjects without diabetes.SUBJECTS AND METHOD: An analytical cross-sectional study was made in the Family Medicine Unitnumber 62 of the Mexican Institute of Social Security, located in the State of México. A randomsample of 87 spouses of patients with DM2 (group ED) was compared with 87 spouses ofsubjects with a normal glucose tolerance (group ENOD). Risk factors for DM2 were investigated;spouses in both groups underwent oral glucose tolerance test, and total cholesterol, triglycerides,blood pressure, body mass index and waist circumference were measured. The frequencyof impaired fasting glucose, impaired glucose tolerance and DM2 were compared inboth groups and the odds ratio was calculated.RESULTS: In the group ED there were 38 (43.7%) subjects with any degree of glucose intolerancevs. 23 (26.4%) in the ENOD group –odds ratio = 2.16 (95% confidence interval, 1.14-4.08) in the bivariate analisys, and odds ratio = 2.37 (95% confidence interval, 1.14-4.91) inthe logistic regression–. In the group ED a higher systolic blood pressure was observed(P=.02). There were no significant differences in age, sex, body mass index, waist circumference,total cholesterol, triglycerides and diastolic blood pressure. The frequency of risk factors fordiabetes was similar in both groups.CONCLUSIONS: In the Mexican population, the spouses of subjects with DM2 have a higher risk ofany alteration in the glucose tolerance than spouses of subjects with a normal glucose metabolism