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1.
Meat Sci ; 192: 108896, 2022 Oct.
Article in English | MEDLINE | ID: mdl-35753267

ABSTRACT

The goal of this study was to confirm and acquire more information about the nitrogen and sulfur compounds existing in the volatile profile of dry fermented sausages from the addition of precursors (proline, ornithine and thiamine), and their role in sausage aroma. To this end, the precursors were added to the formulation of sausages, which were submitted to a fermentation and drying process. The sausage aroma was analyzed by olfactometry technique and Free Choice Profile sensory analysis. The results showed that the addition of precursors impacted the aroma, and reduced the level of oxidation in the final sausages while microbial differences were mainly observed in Orn-sausages. Among the aroma compounds detected only 2-methyl-3-(methylthio)furan verified the effect of thiamine supplementation and the impact on the cured and savoury odours detected in Thia-sausages by Free Choice profile sensory analysis, while no clear effect could be attributed to specific volatile compounds in the nitrogen supplemented sausages.


Subject(s)
Meat Products , Odorants , Fermentation , Meat Products/analysis , Nitrogen , Odorants/analysis , Sulfur , Thiamine
2.
J Appl Microbiol ; 133(1): 200-211, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35050543

ABSTRACT

INTRODUCTION: Debaryomyces hansenii is a yeast widely used in meat fermentations as starter for the purpose of improving the aromatic quality of the final product. However, it has not been the subject of an extensive study regarding phenotypic characteristics important for starter selection, such as the capacity to grow at abiotic stress conditions occurring during fermentation, the ability to generate desirable aromas and the absence of virulence traits in yeasts. AIMS: The aim of this study was to screen 60 strains of D. hansenii isolated from assorted foods for their potential application as starters in dry-cured fermented sausages manufacture. METHODS: The abiotic stress factors tested were low aw and pH and high concentration of salt, acetic acid and lactic acid. The phenotypic virulence traits explored were growth at 37°C, pseudohyphal and biofilm generation, invasiveness and enzymatic activities present in virulent yeasts. The generation of desirable meat aromas was tested in models containing aroma precursors applying an olfactory analysis. A quantitative profiling of stress tolerance was used to test the potential performance of selected strains in meat fermentations. RESULTS: The results demonstrated that most strains displayed no virulence trait or were only positive for biofilm production. Moreover, the strains showed large heterogeneity regarding their tolerance to abiotic stress factors, although most of them could grow at intermediate to high levels of the traits. The sensory analysis was the criteria determining the selection of starter strains. CONCLUSIONS: The evaluation of the phenotypic traits demonstrates that D. hansenii is a safe yeast, it is able to tolerate the stress in meat fermentation and it is able to generate desirable aromas. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study confirm the adequacy of selected D. hansenii strains to be applied as starters in meat products.


Subject(s)
Debaryomyces , Meat Products , Debaryomyces/genetics , Fermentation , Food Microbiology , Odorants/analysis , Saccharomyces cerevisiae , Stress, Physiological , Virulence Factors/analysis
4.
Meat Sci ; 184: 108698, 2022 Feb.
Article in English | MEDLINE | ID: mdl-34700177

ABSTRACT

Dry cured loins containing nitrogen (proline and ornithine) and sulfur (thiamine) compounds as precursors of aroma compounds at two concentration levels were manufactured. The effect of precursor addition on the microbiology and chemical parameters of loins was studied together with the aroma study performed by olfactometry and Free Choice Profile sensory analyses. Addition of precursors did not affect the microbial and chemical parameters, while aroma was affected when precursors were added at the highest level. The dry loin aroma profile was mainly composed by compounds 3-methylbutanal, methional, ethyl 3-methylbutanoate, 3-methylbutanoic acid, 1-octen-3-ol, 2-acetyl-1-pyrroline and 2-acetylpyrrole that contribute to musty, cooked potatoes, fruity, cheesy, mushroom, roasted and meaty odor notes. Proline and ornithine supplementation modified the loins aroma profile producing toasted odors, while the effect of thiamine supplementation on the aroma was revealed by the presence of sulfur derived compounds (methional and 2-methyl-3-(methylthio)furan) that contribute to the "cured meat odor".


Subject(s)
Meat Products/analysis , Meat Products/microbiology , Odorants/analysis , Adult , Animals , Consumer Behavior , Female , Humans , Male , Middle Aged , Olfactometry , Ornithine/chemistry , Proline/chemistry , Swine , Thiamine/chemistry , Volatile Organic Compounds/analysis
6.
Food Chem ; 361: 129997, 2021 Nov 01.
Article in English | MEDLINE | ID: mdl-34029911

ABSTRACT

The contribution of free amino acids and thiamine to the production of potent meat aroma compounds in nitrite-reduced, dry-fermented sausages inoculated with a D. hansenii strain was the objective of this study. For this, three different sausage formulations were manufactured; a control and two formulations reduced by half in nitrate and nitrite and one of them inoculated with D. hansenii. Free amino acids, thiamine content and savoury volatile compounds were analysed. Eleven savoury volatile compounds were quantitated. Among them, the most potent compounds above their odour thresholds were 2-methyl-3-furanthiol, 2-acetyl-1-pyrroline, methional, dimethyl trisulfide and methyl-2-methyl-3-furyl disulfide. Their generation was affected by D. hansenii inoculation as shown by the decrease in methional and methyl 2-methyl-3-furyl disulfide content, and the increase of methionol. Nitrate and nitrite reduction did not significantly affect amino acid and thiamine contents.


Subject(s)
Amino Acids/analysis , Debaryomyces , Fermented Foods/analysis , Meat Products/analysis , Odorants/analysis , Aldehydes/analysis , Fermentation , Fermented Foods/microbiology , Meat Products/microbiology , Nitrates/metabolism , Nitrites/metabolism , Thiamine/analysis , Yeast, Dried
7.
Adv Food Nutr Res ; 95: 131-181, 2021.
Article in English | MEDLINE | ID: mdl-33745511

ABSTRACT

Fermented meat products are important not only for their sensory characteristics, nutrient content and cultural heritage, but also for their stability and convenience. The aroma of fermented meat products is unique and its formation mechanisms are not completely understood; however, the presence of nitrite and nitrate is essential for the development of cured aroma. The use of nitrite and nitrate as curing agents in meat products is based on its preservation activity. Even though their presence has been associated with several risks due to the formation of nitrosamines, their use is guarantee due to their antimicrobial action against Clostridium botulinum. Recent trends and recommendations by international associations are directed to use nitrite but at the minimum concentration necessary to provide the antimicrobial activity against Clostridium botulinum. This chapter discuss the actual limits of nitrite and nitrite content and their role as curing agents in meat products with special impact on dry fermented products. Regulatory considerations, antimicrobial mechanisms and actual trends regarding nitrite reduction and its effect on sensory and aroma properties are also considered.


Subject(s)
Meat Products , Nitrites , Meat , Meat Products/analysis , Nitrates , Odorants
8.
Meat Sci ; 164: 108103, 2020 Jun.
Article in English | MEDLINE | ID: mdl-32145603

ABSTRACT

The reduction of ingoing amounts of nitrate and nitrite in dry fermented sausages was studied together with the impact of Debaryomyces hansenii inoculation on aroma generation. Three different formulations of sausages were manufactured: control (C), reduced in nitrate and nitrite ingoing amounts (R) and reduced R inoculated with D. hansenii (RY). Changes in physicochemical and microbiological parameters, volatile compounds and aroma were investigated at different drying times. Nitrite/nitrate reduction did not seem to affect microbial growth but affected their metabolic activity. Moreover, nitrite/nitrate reduction decreased lipid oxidation and generation of derived volatile compounds. Yeast inoculation limited lipid oxidation and prevented nitrite oxidation. Sausage aroma profile was positively affected by D. hansenii inoculation which contributed to the generation of potent aroma compounds like ethyl ester compounds and 3-methylbutanal. Long drying time impacted sausage aroma profile as well as yeast metabolism. Yeast inoculation counteracted the negative influence of nitrite/nitrate reduction due to its antioxidant capacity, aroma generation and hindered nitrite oxidation.


Subject(s)
Debaryomyces , Meat Products/analysis , Odorants , Animals , Fermentation , Food Handling/methods , Food Microbiology , Meat Products/microbiology , Nitrates/analysis , Nitrites/analysis , Swine , Volatile Organic Compounds/analysis
9.
J Agric Food Chem ; 67(33): 9335-9343, 2019 Aug 21.
Article in English | MEDLINE | ID: mdl-31343169

ABSTRACT

The ability of Debaryomyces hansenii to produce volatile sulfur compounds from sulfur amino acids and the metabolic pathway involved have been studied in seven strains from different food origins. Our results proved that l-methionine is the main precursor for sulfur compound generation. Crucial differences in the sulfur compound profile and amino acid consumption among D. hansenii strains isolated from different food sources were observed. Strains isolated from dry pork sausages displayed the most complex sulfur compound profiles. Sulfur compound production, such as that of methional, could result from chemical reactions or yeast metabolism, while according to this study, thioester methyl thioacetate appeared to be generated by yeast metabolism. No relationship between sulfur compounds production by D. hansenii strains and the expression of genes involved in sulfur amino acid metabolism was found, except for the ATF2 gene in the L1 strain for production of methyl thioacetate. Our results suggest a complex scenario during sulfur compound production by D. hansenii.


Subject(s)
Amino Acids, Sulfur/metabolism , Debaryomyces/metabolism , Meat Products/analysis , Meat Products/microbiology , Sulfur Compounds/metabolism , Animals , Debaryomyces/genetics , Fermented Foods/analysis , Fermented Foods/microbiology , Fungal Proteins/genetics , Fungal Proteins/metabolism , Sulfur Compounds/chemistry , Swine , Volatilization
10.
Meat Sci ; 147: 100-107, 2019 Jan.
Article in English | MEDLINE | ID: mdl-30219361

ABSTRACT

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).


Subject(s)
Food Preservatives/analysis , Food Storage/methods , Meat Products/microbiology , Nitrates/analysis , Odorants/analysis , Animals , Bacteria/growth & development , Bacteria/isolation & purification , Color , Fungi/growth & development , Fungi/isolation & purification , Meat Products/analysis , Swine , Vacuum
11.
Int J Food Microbiol ; 282: 84-91, 2018 Oct 03.
Article in English | MEDLINE | ID: mdl-29933128

ABSTRACT

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.


Subject(s)
Bacteria/metabolism , Flavoring Agents/analysis , Food Preservatives/analysis , Fungi/metabolism , Meat Products/microbiology , Nitrates/analysis , Animals , Bacteria/classification , Bacteria/growth & development , Bacteria/isolation & purification , Fermentation , Fermented Foods/analysis , Flavoring Agents/metabolism , Fungi/genetics , Fungi/growth & development , Fungi/isolation & purification , Humans , Meat Products/analysis , Nitrites/analysis , Odorants/analysis , Sodium Chloride , Swine , Taste
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