Improvement the aroma of reduced fat and salt fermented sausages by Debaromyces hansenii inoculation

The Aroma of Non-Fermented and Fermented Dry-Cured Meat Products: Savory and Toasted Odors

Volatile chemicals containing nitrogen and sulfur as key odors in dry-cured meat products have extremely low odor thresholds. These compounds play an important part in the overall uniqueness and characteristic flavor of dry-cured meat products, contributing to savory and toasted aroma sensations, respectively. In this review, we define the different volatiles and aroma compounds related to the flavor of dry-cured meat products. Moreover, the main differences regarding volatiles, aromas, and flavor profiles from non-fermented and fermented dry-cured meat products are summarized. Comparisons using the same volatile extraction techniques revealed that dry loins contained the most sulfur- and nitrogen-containing compounds, while complex flavor and aroma compounds in fermented sausages were greatly impacted by the fermentation process. The screening and quantification of savory and toasted odors showed that methionol, dimethyl sulfide, and 2-methyl-3-(methylthio)furan were mainly reported in non-fermented products, whereas pyrazines were mainly detected in fermented meat products. Finally, the different mechanisms in the generation of savory and toasted aromas, including chemical reactions and biochemical reactions by microorganisms (bacteria, yeast, and molds), are discussed. These discussions will help to better understand the complex flavor of dry-cured meat products.

The effects of fermented sausage quality driven by reduction of NaCl: Investigation into the microbial community and flavor profiles

The primary objective of this study was to evaluate the impact of NaCl reduction (2.50 %, 2.25 %, 2.00 %, 1.75 %, and 1.50 %) on the physicochemical characteristics, microbial communities, flavor profile, and sensory characteristics of fermented sausage. The water activity increased with the reduction of the NaCl content from 2.50 % to 1.50 %, while the pH value, chewiness, and hardness decreased. High-throughput sequencing results showed that Staphylococcus saprophyticus, Staphylococcus kloosii, Latilactobacillus sakei, and Enterococcus pseudoavium were the dominant bacteria at the end of fermentation, and the 2.00 % NaCl treatment exhibits the highest bacterial diversity. A total of 32 volatile compounds were identified, of which there were 16 main volatile compounds. Sensory evaluation showed lower scores for chewiness, color, and flavor in sausages with less than 1.75 % NaCl. Furthermore, the correlation analysis showed that four bacterial species (Lb. sakei, S. saprophyticus, S. kloosii, and E. pseudoavium) were positively correlated with the major volatile compounds such as nonanal, ethyl propionate, ethyl hexanoate, and 1-hepten-3-one. Overall, it can be concluded that when NaCl content is reduced to less than 1.75 %, compensatory measures are needed to achieve better quality and flavor in fermented sausage. This study offers a thorough understanding of the association between bacterial communities and volatile flavors in low-salt fermented sausage.

Dual Role of Yeasts and Filamentous Fungi in Fermented Sausages

This contribution aims to review the presence and the potential double role-positive or beneficial and negative or harmful-of fungi in fermented sausages as well as their use as starter cultures. Traditionally, studies have been focused on lactic acid bacteria; however, over the years, interest in the study of fungi has increased. The important contribution of yeasts and filamentous fungi to the quality and safety of fermented sausages has emerged from reviewing the literature regarding these fermented products. In conclusion, this review contributes to the existing literature by considering the double role of filamentous fungi and yeasts, the global fermented sausage market size, the role and use of starters, and the starters mainly present in the worldwide market, as well as the main factors to take into account to optimize production. Finally, some suggestions for future broadening of the sector are discussed.

Effect of selected agents for ochratoxin A biocontrol on the colour, texture and volatile profile of dry-cured fermented sausages

BACKGROUND

Traditional dry-cured fermented sausages favour the growth of an autochthonous microbial population, which plays an important role in their sensory aspects. However, some moulds can produce mycotoxins such as ochratoxin A (OTA). The biocontrol agents (BCAs) Debaryomyces hansenii FHSCC 253H and Staphylococcus xylosus FHSCC Sx8 have been demonstrated to reduce OTA production in dry-cured meat products, but their influence in the sensory characteristics of sausages has to be tested. The aim of this study was to evaluate the effect of these BCAs on the colour, texture and volatile profile of dry-cured fermented sausages.

RESULTS

D. hansenii caused few differences in the tested parameters with respect to the control batch. S. xylosus modified the texture and colour, although the values found were within the range expected for dry-cured fermented sausages 'salchichón'. Additionally, the volatile profile revealed the potential antioxidant effect of both BCAs and their ability to produce compounds associated with the ripened aroma that could increase product acceptability.

CONCLUSION

The results indicate that there were no inconveniences in implementing both BCAs during the processing of dry-cured fermented sausages 'salchichón'. Moreover, D. hansenii FHSCC 253H could improve the volatile profile of this product. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Isolation of Debaryomyces hansenii and selection of an optimal strain to improve the quality of low-grade beef rump (middle gluteal) during dry aging

OBJECTIVE

The objective of this study was to evaluate the effect of Debaryomyces hansenii isolated from dry-aged beef on the tenderness and flavor attributes of low-grade beef during dry aging.

METHODS

Five D. hansenii strains were isolated from dry-aged beef samples. The rump of low-grade beef was inoculated with individual D. hansenii isolates and subjected to dry aging for 4 weeks at 5°C and 75% relative humidity. Microbial contamination levels, meat quality attributes, and flavor attributes in the dry-aged beef were measured.

RESULTS

Of the five isolates, the shear force of dry-aged beef inoculated with SMFM201812-3 and SMFM201905-5 was lower than that of control samples. Meanwhile, all five isolates increased the total free amino acid, glutamic acid, serine, glycine, alanine, and leucine contents in dry-aged beef. In particular, the total fatty acid, palmitic acid, and oleic acid contents in samples inoculated with D. hansenii SMFM201905-5 were higher than those in control samples.

CONCLUSION

These results indicate that D. hansenii SMFM201905-5 might be used to improve the quality of beef during dry aging.

Short-Term Changes in Aroma-Related Volatiles in Meat Model: Effect of Fat and D. hansenii Inoculation

This study assessed the effect of replacing pork lard with coconut oil and Debaryomyces hansenii inoculation on the biotransformation of amino acids into volatile compounds in a meat model system. Yeast counts, solid-phase microextraction, and gas chromatography/mass spectrometry were used to assess yeast growth and volatile production, respectively. Yeast growth was confirmed until 28 d, although the volatile profile changed until 39 d. Forty-three volatiles were quantified, and their odor activity values (OAVs) were calculated. The presence of fat and yeasts contributed to differences in volatiles. In pork lard models, a delayed formation of lipid-derived aldehyde compounds was observed, whereas in coconut oil models, the generation of acid compounds and their respective esters was enhanced. Yeast activity affected amino acid degradation, which produced an increase in branched-chain aldehydes and alcohols. The aroma profile in the coconut models was influenced by hexanal, acid compounds, and their respective esters, whereas in pork lard models, aroma was affected by methional (musty, potato) and 3-methylbutanal (green, cocoa). The yeast inoculation contributed to the generation of 3-methylbutanoic acid (cheesy) and phenylethyl alcohol (floral). The type of fat and yeast inoculation produced a differential effect on the aroma.

Autochthonous Cultures to Improve Safety and Standardize Quality of Traditional Dry Fermented Meats

Traditional dry fermented meat products are obtained artisanally in many countries, where they represent a gastronomic heritage well distinguished from industrial counterparts. This food category is most often obtained from red meat, a food commodity that is under attack because of evidence of increased risk of cancer and degenerative diseases with high consumption. However, traditional fermented meat products are intended for moderate consumption and gastronomic experience, and, as such, their production must be continued, which would also help safeguard the culture and economy of the geographical areas of origin. In this review, the main risks attributed to these products are considered, and how these risks are reduced by the application of autochthonous microbial cultures is highlighted by reviewing studies reporting the effects of autochthonous lactic acid bacteria (LAB), coagulase negative staphylococci (CNS), Debaryomyces hansenii and Penicillium nalgiovense on microbiological and chemical safety and on sensory attributes. The role of dry fermented sausages as a source of microorganisms that can be beneficial to the host is also considered. From the results of the studies reviewed here it appears that the development of autochthonous cultures for these foods can ensure safety and stabilize sensory characteristics and has the capacity to be extended to a larger variety of traditional products.

Influence of soaking and solvent extraction for deodorization of texturized pea protein isolate on the formulation and properties of hybrid meat patties

BACKGROUND

Hybrid batters constitute the base for the processing of cooked and dry meat analogues. The use of texturized plant proteins in their formulation is a key strategy to reduce the consumption of animal proteins, although off-flavors present in these plant proteins often cause sensory rejection. The aim was to study the effect of a deodorization process of pea protein, for their use in hybrid meat batters at different percentages of substitution.

RESULTS

Hybrid patties with higher percentages of pea protein showed higher values of yellowness, pH, and water activity, whereas hardness was reduced. Soaking treatment with ethanol for deodorization of the texturized pea protein increased humidity and pH in all patties but reduced the textural properties (hardness, springiness, cohesiveness, and chewiness). The addition of oat flour improved the patty texture at higher percentages of pea protein, but in soaked deodorized patty formulations it affected volatile retention. Volatile compounds related to off-flavors (aldehydes, alcohols, acid compounds, ketones, and pyrazines) appeared significantly increased as the pea percentage increased, although these were efficiently removed by the soaking deodorizing process applied.

CONCLUSION

Soaking of the texturized pea protein with ethanol is an effective strategy to reduce off-flavors in hybrid meat patties. However, it produces changes in the textural characteristics by the solubilization of the proteins of the texturized pea, reducing the availability to form a network and affecting volatile retention. The formulation of hybrid batter should be controlled in all sensory aspects for the processing of cooked and dry cured meat product analogues. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Flavour Profile of Traditional Dry Sausage Prepared with Partial Substitution of NaCl with KCl

The effects of partial substitution of NaCl with 0%, 20%, 30% and 40% KCl on the physical characteristics, bacterial community and flavour profile of traditional dry sausage were investigated in this study. With the increase in KCl substitution ratio, the moisture content, astringency, bitterness and umami increased significantly, and the saltiness gradually decreased (p < 0.05). The high-throughput sequencing results showed that the dry sausages with KCl substitution had relatively high abundances of Staphylococcus. For volatile compounds, increasing the KCl substitution ratio reduced the formation of aldehydes, ketones and some alcohols, but promoted the formation of acids and esters (p < 0.05). Sensory evaluation and partial least square regression analysis showed that the dry sausages with 20% and 30% KCl were similar in overall physical and microbial properties, flavour profiles and sensory attributes, and the sausages with 40% KCl were characterized by taste defects. Overall, partial substitution of NaCl with 30% KCl could ensure the acceptable flavour and sensory attributes of dry sausages.

Effect of Starter Cultures on Quality of Fermented Sausages

The expansion and advancement of the meat product market have increased the demand for fermented sausages. A typical method for manufacturing high-quality fermented sausages is using a starter culture, which improves the taste, aroma, and texture. Currently, the starter culture for manufacturing fermented sausages is mainly composed of microorganisms such as lactic acid bacteria, yeast, and fungi, which generate volatile compounds by the oxidation of fatty acids. In addition, protein decomposition and changes in pH occur during the fermentation period. It can positively change the texture of the fermented sausage. In this review, we discuss the requirements (improving food safety, the safety of starter culture, enzyme activity, and color) of microorganisms used in starter cultures and the generation of flavor compounds (heptanal, octanal, nonanal, hexanal, 2-pentylfuran, 1-penten-3-ol, and 2-pentanone) from lipids. Furthermore, quality improvement (hardness and chewiness) due to texture changes after starter culture application during the manufacturing process are discussed.

Insights into the flavor perception and enhancement of sodium-reduced fermented foods: A review

Salt (sodium chloride, NaCl) is a vital ingredient in fermented foods, which affects their safety, texture, and flavor characteristics. Recently, the demand for reduced-sodium fermented foods has increased, as consumers have become more health-conscious. However, reducing sodium content in fermented foods may negatively affect flavor perception, which is a critical quality attribute of fermented foods for both the food industry and consumers. This review summarizes the role of salt in the human body and foods and its role in the flavor perception of fermented foods. Current sodium reduction strategies used in the food industry mainly include the direct stealth reduction of NaCl, substituting NaCl with other chloride salts, and structure modification of NaCl. The odor-induced saltiness enhancement, application of starter cultures, flavor enhancers, and non-thermal processing technology are potential strategies for flavor compensation of sodium-reduced fermented foods. However, reducing sodium in fermented food is challenging due to its specific role in flavor perception (e.g., promoting saltiness and volatile compound release from food matrices, inhibiting bitterness, and changing microflora structure). Therefore, multiple challenges must be addressed in order to improve the flavor of low-sodium fermented foods. Future studies should thus focus on the combination of several strategies to compensate for the deficiencies in flavor resulting from sodium reduction.

Staphylococcus spp. and Lactobacillus sakei Starters with High Level of Inoculation and an Extended Fermentation Step Improve Safety of Fermented Sausages

Paio do Alentejo (PA) is one of the most popular dry-fermented sausages in Portugal. The aim of the present work was to evaluate the effect of a high concentration of starter cultures with an extended fermentation step on the safety and quality of PA. Physicochemical parameters, microbiological parameters, biogenic amines, colour, texture profile, and sensory attributes were assessed. Five starters were selected based on our previous works. Staphylococcus equorum S2M7, Staphylococcus xylosus CECT7057, Lactobacillus sakei CV3C2, Lactobacillus sakei CECT7056, and a yeast strain (2RB4) were co-inoculated in meat batters at a concentration of 108 cfu/g for bacteria and 106 cfu/g for yeast strain, and 0.25% dextrose was added. Inoculated starters significantly reduced pH, Listeria monocytogenes counts, and total content in biogenic amines. The studied starter cultures did not compromise the sensory characteristics of PA, and thus, their use can be considered to protect these sausages and contribute to their safety.

The Effect of Catabolic Transformations of Proteins and Fats on the Quality and Nutritional Value of Raw Ripened Products from Zlotnicka Spotted and Zlotnicka White Meat

The aim of the study was to compare the advancement of the ripening as well as catabolic changes in proteins and fats of Zlotnicka Spotted (ZS) and Zlotnicka White (ZW) meat and their impact on the quality and nutritional value of ready-to-eat products. The meat of the breeds ZS and ZW differed not only in the basic chemical composition but also in the susceptibility to catabolic transformations of proteins and lipids, which translated into a separate technological and nutritional quality as well as the profile of volatile odor compounds. Loins due to their compact histological structure, low pH (5.4) and decreased water activity (0.92–0.93) were characterized by a lower number of coagulase-negative cocci (3.3 log cfu/g) compared to hams. The products of both breeds differed in the content of selected neutral glucogenic amino acids with a pI in the range of 5.6–6.1 mainly. The content of biogenic amines was therefore completely dependent on the metabolic potential of acidifying bacteria. Larger number of lactic acid bacilli (7.5–7.7 log cfu/g) and lactic acid cocci (7.9–8.3 log cfu/g), as well as a higher content of saturated (55.2–53.7%) and polyunsaturated fatty acids (6.4–7.0%) shaped the final pH of hams (5.3). Presence of aldehydes, ketones and alcohols indicated existing fat oxidation despite the small values of the TBA index of hams (1.1 mg/kg) and loins (0.4–0.6 mg/kg). The volatile compounds that differentiated products of ZS and ZW formed by the oxidation and microbial activity, were, primarily: octanal, 1-hydroxypropan- 2-one, 3-methylpentan-2-one, propane-1,2-diol, 2,5-dimethylfuran and 3-hydroxybutan- 2-one, butane-2,3-dione, butane-1,2-diol, respectively.

Effect of Salt Content Reduction on Food Processing Technology

Higher salt intake is associated with the risk of cardiovascular and kidney diseases, hypertension and gastric cancer. Salt intake reduction represents an effective way to improve people’s health, either by the right choice of food or by a reduction of added salt. Salt substitutes are often used and also herb homogenates are treated by high pressure technology. Salt reduction significantly influences the shelf life, texture, pH, taste, and aroma of cheese. The composition of emulsifying salts or starter cultures must be modified to enact changes in microbial diversity, protease activity and the ripening process. The texture becomes softer and aroma atypical. In bakery products, a salt reduction of only 20–30% is acceptable. Water absorption, dough development, length and intensity of kneading and stability of dough are changed. Gluten development and its viscoelastic properties are affected. The salt reduction promotes yeast growth and CO₂ production. Specific volume and crust colour intensity decreased, and the crumb porosity changed. In meat products, salt provides flavour, texture, and shelf life, and water activity increases. In this case, myofibrillar proteins’ solubility, water binding activity and colour intensity changes were found. The composition of curing nitrite salt mixtures and starter cultures must be modified.

Meaty aroma notes from free amino acids and thiamine in nitrite-reduced, dry-fermented, yeast-inoculated sausages

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.

Indigenous Microbiota to Leverage Traditional Dry Sausage Production

The main issue addressed in this review is the need for innovation in the artisanal production of dry fermented sausages-leveraging rather than discarding tradition, together with some practical strategies available to achieve it. Throughout the text, emphasis is placed on the autochthonous microbiota responsible for the identity and unique sensory characteristics of these products. The available strategies to introduce innovation in this manufacturing process rely on metabolic flexibility of microbial strains. In this sense, this review evaluates the application of several tools aimed at improving the quality and safety of artisanal dry fermented sausages focusing on the microbial community role. The most studied alternatives to enhance dry sausage production comprise the use of autochthonous starter cultures-including functional and/or probiotic strains, the production of bacteriocins, and the generation of bioactive peptides, which have been thoroughly covered herein. The purpose of this work is to review recent research about novel different strategies available for food technologists to improve safety and quality in the manufacture of dry fermented sausages. Additional support strategies-quality product registers and innovation through tradition-have been suggested as complementary actions towards a successful introduction of indigenous microbial communities into traditional dry sausage production.

The Maillard Reaction as Source of Meat Flavor Compounds in Dry Cured Meat Model Systems under Mild Temperature Conditions

Flavor is amongst the major personal satisfaction indicators for meat products. The aroma of dry cured meat products is generated under specific conditions such as long ripening periods and mild temperatures. In these conditions, the contribution of Maillard reactions to the generation of the dry cured flavor is unknown. The main purpose of this study was to examine mild curing conditions such as temperature, pH and a_w for the generation of volatile compounds responsible for the cured meat aroma in model systems simulating dry fermented sausages. The different conditions were tested in model systems resembling dry fermented sausages at different stages of production. Three conditions of model system, labeled initial (I), 1st drying (1D) and 2nd drying (2D) and containing different concentrations of amino acid and curing additives, as well as different pH and a_w values, were incubated at different temperatures. Changes in the profile of the volatile compounds were investigated by solid phase microextraction and gas chromatography mass spectrometry (SPME-GS-MS) as well as the amino acid content. Seventeen volatile compounds were identified and quantified in the model systems. A significant production of branched chain volatile compounds, sulfur, furans, pyrazines and heterocyclic volatile compounds were detected in the model systems. At the drying stages, temperature was the main factor affecting volatile production, followed by amino acid concentration and a_w. This research demonstrates that at the mild curing conditions used to produce dry cured meat product volatile compounds are generated via the Maillard reaction from free amino acids. Moreover, in these conditions a_w plays an important role promoting formation of flavor compounds.

Autochthonous Yeast from Pork and Game Meat Fermented Sausages for Application in Meat Protection and Aroma Developing

Simple Summary

Yeasts are microorganisms presented naturally in meat products microbiota, which carry out an essential role in the maturation process of fermented sausages. The maturation of this type of product could be better controlled by the addition of a starter culture or a mix of strains that could standardize the process in diverse factories. Moreover, it would be favorable to find cultures that, not only conduct the curing process, but also present an added value such as the meat product protection (antioxidant capability and biocontrol activity). Yeasts also have an important role in the meat product aroma development. Therefore, it would be interesting to select a pleasant-aroma forming strain in order to elaborate a future starter culture for fermented sausage maturation.

Abstract

The wild yeast community was studied in fermented sausages from pork and game meat (deer and wild boar) during the maturation process from different curing rooms. Although the biotechnological importance of yeasts in the maturation process of pork sausages is known, there is a lack of information for sausage maturation involving game meat. A total of 123 yeasts were isolated and, by amplifying and sequencing of the ITS region, were classified in 14 species. Debaryomyces hansenii, Kazachstania servazzii, and Wickerhamomyces anomalus were isolated in both pork and game samples. The PCR-RAPD technique differentiated between 26 and 18 strains from pork and game meat sausages, respectively. The physicochemical parameters and their relationship with the yeast community were also studied. The antioxidant and anti-lipid peroxidation capability were analyzed and the 70% and 50% of the tested strains showed these abilities, respectively. Moreover, the biocontrol capability against mycotoxigenic molds was found in 19 strains, but better results were observed in game meat yeasts. On the other hand, almost 30% of strains produce a pleasant olfactory aroma, and volatile compounds associated with the yeast pathway metabolic during the maturation process have been characterized such as esters, aldehydes, fusel alcohols, etc. This study has allowed a better understanding of the biodiversity of this type of food, as well as selecting potential yeast strains for their future use as starters.

Effects of Preservative Agents on Quality Attributes of Dry-Cured Fermented Sausages

Enterococcus faecium SE920, Debaryomyces hansenii FHSCC 253H, Penicillium chrysogenum CECT 20922, producer of the antifungal protein PgAFP, and this protein itself have previously been proposed to control toxigenic molds in dry-cured meat products. However, their effects on the usual microbial population, and the sensory characteristics of these foods, have not yet been evaluated. The aim of this study was to assess the viability of the inoculation of these protective cultures, and their impact on the quality of dry-cured fermented sausages. These microorganisms were co-inoculated with a native desirable population (Penicillium nalgiovense, P. chrysogenum, D. hansenii, and Staphylococcus vitulinus) in a dry-cured fermented sausage (salchichón)-based medium in the presence and absence of PgAFP. Macroscopically, the biocontrol candidates did not produce relevant changes in the growth of the native population, enabling their coexistence. However, PgAFP causes the alteration of the hyphae structure in desirable molds. Thus, PgAFP was discarded for use on the surface of raw dry-cured fermented sausages (salchichón) in the pilot plant. The used biocontrol agents did not negatively affect the physico-chemical parameters of the dry-cured fermented sausages (salchichón) after ripening, which showed the typical volatile profile and odor. Thus, the application of E. faecium SE920, D. hansenii FHSCC 253H, and P. chrysogenum CECT 20922 as protective cultures against toxigenic molds during the ripening of dry-cured fermented sausages does not modify their typical sensorial quality.

Autochthonous Starter Cultures Are Able to Reduce Biogenic Amines in a Traditional Portuguese Smoked Fermented Sausage

Traditional smoked fermented sausages are highly appreciated in Portugal and are mostly manufactured according to traditional procedures. The aim of the present work was to evaluate the effect of autochthonous starter cultures on the safety and quality of a smoked fermented sausage, Painho da Beira Baixa (PBB), preserving its sensory quality. Physicochemical parameters, namely pH and water activity (a_W), microbiological parameters, biogenic amines, colour, texture profile and sensory attributes were assessed. Different starters were selected based on our previous work. Staphylococcus equorum S2M7, Staphylococcus xylosus CECT7057, Lactobacillus sakei CV3C2, Lactobacillus sakei CECT7056 and a yeast strain (2RB4) were co-inoculated in meat batters at defined concentrations. Starters had a significant effect on the reduction of pH. Enterobacteria and Listeria monocytogenes were not detected in inoculated end-product sausages. Moreover, sausages inoculated with S. equorum S2M7/L. sakei CV3C2/yeast 2RB4 showed a significant reduction in the total content of biogenic amines. No significant differences between treatments were observed for colour and texture parameters, except for adhesiveness. The studied starters did not compromise the sensory characteristics of PBB. To our knowledge, this is the first comprehensive study on the quality and safety of this type of smoked fermented sausage from the central region of Portugal.

Impact of a 25% Salt Reduction on the Microbial Load, Texture, and Sensory Attributes of a Traditional Dry-Cured Sausage

Catalão is a Portuguese dry-cured traditional sausage, highly appreciated for its distinctive sensory properties. The aim of this study was to evaluate the impact of a 25% salt reduction on Catalão manufactured with either purebred Alentejano (Al) or crossbred Iberian × Duroc (IDr) pork meat, on its physicochemical and microbiological stability, texture parameters, and sensory attributes. No significant effect of salt reduction or genotype was observed for pH, aW, and microbiological parameters. PUFA content was significantly higher for Al Catalão, particularly due to the content in linoleic and linolenic fatty acids. IDr 3% NaCl samples had the highest mean n6/n3 PUFA ratio, and the highest mean values for the atherogenicity and thrombogenicity indices, showing that both genotype and salt content influence these nutritional indices. Texture profile of Catalão was significantly influenced by salt content and genotype. Al samples were less adhesive, cohesive, and easier to chew. Low-salt Catalão was harder, more adhesive, and less cohesive, with lower resilience and higher chewiness values. Regarding sensory attributes, salt content influenced the product aroma, with reduced-salt sausages being evaluated as significantly less aromatic. Overall, a 25% salt reduction did not have a significant impact on the quality, stability, and sensory evaluation of Catalão.

The life and times of yeasts in traditional food fermentations

Yeasts are eukaryotic microorganisms which have a long history in the biotechnology of food production, as they have been used since centuries in bread-making or in the production of alcoholic beverages such as wines or beers. Relative to this importance, a lot of research has been devoted to the study of yeasts involved in making these important products. The role of yeasts in other fermentations in association with other microorganisms - mainly lactic acid bacteria - has been relatively less studied, and often it is not clear if yeasts occurring in such fermentations are contaminants with no role in the fermentation, spoilage microorganisms or whether they actually serve a technological or functional purpose. Some knowledge is available for yeasts used as starter cultures in fermented raw sausages or in the production of acid curd cheeses. This review aimed to summarize the current knowledge on the taxonomy, the presence and potential functional or technological roles of yeasts in traditional fermented plant, dairy, fish and meat fermentations.

Debaryomyces hansenii Metabolism of Sulfur Amino Acids As Precursors of Volatile Sulfur Compounds of Interest in Meat Products

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.

Lipolysis and aroma generation as mechanisms involved in masking boar taint in sodium reduced fermented sausages inoculated with Debaryomyces hansenii yeast

BACKGROUND

The use of boar back fat for processing of fermented sausages may cause the presence of abnormal odours. In dry-cured products, ripening time is essential to develop the sensory characteristics. Yeast has been proposed as an alternative to mask boar taint odour through its metabolic activity but it is necessary to elucidate which mechanisms are involved. The aim is to study the effect of Debaryomyces hansenii inoculation on the lipolysis process and generation of aroma compounds in fermented sausages manufactured with boar back fat at two different ripening times.

RESULTS

D. hansenii inoculated sausages had a higher degree of lipolysis as demonstrated by higher content of free fatty acids, ester compounds and branched aldehydes which contribute the fruity odour. The increase in lipolysis produced by D. hansenii inoculation was not followed by an increase in oxidation during processing possibly due to the metabolic activity of yeast. The effect of back fat type was scarcely appreciated whereas ripening time had a stronger effect on sausage. Boar sausages were characterised by a lower polyunsaturated fatty acid profile and lesser lipolysis than gilt sausages.

CONCLUSION

Yeast inoculation with D. hansenii and long ripening time were appropriate strategies to limit the perception of boar taint in dry fermented sausages. © 2017 Society of Chemical Industry.

Effects of Debaryomyces hansenii treatment on intestinal microorganisms in mice with antibiotics-induced diarrhea

To investigate the influence of Debaryomyces hansenii treatment on intestinal microorganisms in mice with antibiotics-induced diarrhea, mouse model of antibiotics-induced diarrhea was created by gavaging mice with mixed antibiotics (23.33 mL/kg/days) composed of gentamycin sulfate and cefradine for 5 days. Mice with the symptom of diarrhea were then treated with D. hansenii by intragastric administration. The control group mice were given with sterile water. After 4 day treatment, total DNA of intestinal microflora of treated and control mice was extracted, and their quantities were measured by sequencing the V4 region of 16S rDNA. The results showed that when compared to the control (sterile water), treatment with D. hansenii increased the operational taxonomic units (OTUs) of intestinal bacteria. The Chao index in diarrhea treated group was higher than diarrhea control group and was similar to healthy control group, while all differences had no significance (P > 0.05). D. hansenii treatment increased the Shannon index but not significantly (P > 0.05). Moreover, there was not significant impact on density and diversity of intestinal bacterial population at phylum and genus levels (P > 0.05). Interestingly, D. hansenii treatment recovered the population density of certain bacterium species, such as Bacteroidaceae (in family level) (P < 0.05). Our results indicate that D. hansenii has potency of adjusting the density and diversity of intestinal bacteria and recovering the population density of Bacteroidaceae in family level.

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.

Yeast inoculation as a strategy to improve the physico-chemical and sensory properties of reduced salt fermented sausages produced with entire male fat

Yeast inoculation of dry fermented sausages manufactured with entire male fat was evaluated as a strategy to improve sausage quality. Four different formulations with entire male/gilt back fat and inoculated/non-inoculated with Debaryomyces hansenii were manufactured. The use of entire male back fat produced the highest weight losses, hardness and chewiness in dry sausages. Consumers clearly distinguished samples according to drying time and D. hansenii inoculation while the use of entire/gilt back fat was not highly perceived. The presence of androstenone and skatole was close to their sensory thresholds. Androstenone was not degraded during the process but skatole was affected by yeast inoculation. D. hansenii growth on the surface regulated water release during ripening, reduced hardness and chewiness in entire male sausages and resulted with similar texture to gilt sausages. Yeast inoculation inhibited lipid oxidation providing fruity odours and less oxidized fatty sausages in the sensory analysis. The effectiveness of yeast to mask boar taint was demonstrated by sensory analysis.

Effect of the use of entire male fat in the production of reduced salt fermented sausages

The effect of the use of entire male fat and salt reduction in dry fermented sausages was evaluated. Four different sausage formulations were manufactured with back fat from gilt or entire male and two different salt contents. The physicochemical parameters, sensory characteristics, texture, lipid composition, volatile compounds and boar taint compounds were analysed. The use of entire male fat produced the highest weight losses producing high hardness and chewiness while salt reduction produced a decrease in hardness. Entire male sausages had the lowest oxidation values due to the low content of C18:2n6 while salt reduction did not affect the oxidation process. Boar taint odour was due to the presence of androstenone and skatole but entire male fat sausages had different generations of volatile compounds. The presence of androstenone was perceived by consumers as abnormal odours but also other sausage characteristics such as texture (high hardness) and oxidation were detected due to the different chemical compositions of entire males versus gilts.

Effect of added autochthonous yeasts on the volatile compounds of dry-cured hams

Three yeast strains belonging to Debaryomyces and Hyphopichia spp., isolated from dry-cured hams and previously tested for biocontrol activity against toxigenic Penicillium nordicum, were investigated for ability in colonising ham surface. Hams were twice yeast-inoculated onto the unskinned muscle surface during ripening and processed up to full maturation in two manufacturing plants. The yeast strains and the manufacturing plants differed (P < 0.05) in surface populations, volatile compounds and sensory descriptors of matured hams. Sensory scores for each of the yeast-inoculated groups were higher or similar to the non-inoculated ones (controls). Debaryomyces strains were regarded as those most fit to colonise the ham surface under the ecological conditions of dry-curing rooms, hence to qualify as biocontrol agents against the growth of undesired mould and preserve the typical sensory properties of dry-cured hams.