Alicia Olivares

Sensory acceptability of slow fermented sausages based on fat content and ripening time

Low fat dry fermented sausages were manufactured using controlled ripening conditions and a slow fermented process. The effect of fat content and ripening time on the chemical, colour, texture parameters and sensory acceptability was studied. The fat reduction in slow fermented sausages produced an increase in the pH decline during the first stage of the process that was favoured by the higher water content of the low fat sausages. Fat reduction did not affect the external appearance and there was an absence of defects but lower fat content resulted in lower sausage lightness. The sausage texture in low fat sausages caused an increase in chewiness and at longer ripening times, an increase in hardness. The sensory acceptability of the fermented sausages analyzed by internal preference mapping depended on the different preference patterns of consumers. A group of consumers preferred sausages with high and medium fat content and high ripening time. The second group of consumers preferred sausages with low ripening time regardless of fat content except for the appearance, for which these consumers preferred sausages of high ripening time. Finally, the limit to produce high acceptability low fat fermented sausages was 16% fat content in the raw mixture that is half the usual content of dry fermented sausages.

Effect of fat content on aroma generation during processing of dry fermented sausages.

Dry fermented sausages with different fat contents were produced (10%, 20% and 30%). The effect of fat content and ripening time on sensory characteristics, lipolysis, lipid oxidation and volatile compounds generation was studied. Also, the key aroma components were identified using gas chromatography (GC) and olfactometry. High fat sausages showed the highest lipolysis and lipid oxidation, determined by free fatty acid content and thiobarbituric acid reactive substances (TBARS), respectively. A total of 95 volatile compounds were identified using SPME, GC and mass spectrometry (MS). Fat reduction decreased the generation of lipid derived volatile compounds during processing while those generated from bacterial metabolism increased, although only at the first stages of processing. The consumers preference in aroma and overall quality of high and medium fat sausages was related to the aroma compounds hexanal, 2-nonenal, 2,4-nonadienal, ethyl butanoate and 1-octen-3-ol which contributed green, medicinal, tallowy, fruity and mushroom notes.

Selected Ion Flow Tube-Mass Spectrometry for Absolute Quantification of Aroma Compounds in the Headspace of Dry Fermented Sausages

The meat industry is interested in rapid control of the sensory quality of meat products. Selected ion flow tube mass spectrometry (SIFT-MS) has been applied to the rapid, real-time quantification of 31 volatile aroma compounds present in the headspace (HS) of dry fermented sausages. Three batches of fermented sausages with different fat contents (10, 20, and 30%) were monitored throughout the processing time. SIFT-MS revealed significant changes in the concentration of all the aroma compounds during the processing time. Moreover, among the various batches of the sausages, significant differences were revealed in their HS concentration of butanal, 2-pentenal, hexanal, 2-butanone, 2,3-butanedione, ethanol, ethyl formate, hexanoic acid, and dimethyl disulfide. In addition, highly volatile compounds were detected and quantified using our real-time SIFT-MS technique that are apparently not generally seen by trace gas extraction and GC techniques.

SPME-GC-MS versus Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) analyses for the study of volatile compound generation and oxidation status during dry fermented sausage processing.

The use of selected ion flow tube mass spectrometry (SIFT-MS) and gas chromatography-mass spectrometry together with solid phase microextraction (GC-MS-SPME) has been compared in the analysis of volatile compounds during dry fermented sausage processing. Thus, the headspace (HS) of samples of dry fermented sausages with different fat contents was analyzed during their manufacture using both techniques, and significant and positive correlations were found between SIFT-MS and SPME-GC-MS measurements for the compounds pentanal, hexanal, 2-heptenal, octanal, 2-nonenal, 2-butanone, 2-pentanone, ethanol, acetic acid, and hexanoic acid. The oxidative status of fermented sausages during processing was also evaluated, and a significant correlation was obtained between the HS concentration of lipid autoxidation volatile compounds measured by SIFT-MS and SPME-GC-MS and the level of thiobarbituric acid reactive substances (TBARS) in the sausage. The hexanal measured by SIFT-MS resulted in a higher correlation coefficient (r = 0.936) than that obtained using SPME-GC-MS (r = 0.927). SIFT-MS is shown to be a fast, real time analytical technique for monitoring changes in the profile of volatile compounds in dry fermented sausages during processing and a useful tool to evaluate the oxidative status of meat products.

Rapid detection of lipid oxidation in beef muscle packed under modified atmosphere by measuring volatile organic compounds using SIFT-MS

The objective of this work was to evaluate the use of a direct analysis technique (SIFT-MS) to measure the lipid oxidation process in beef meat packed under high oxygen atmosphere and compare it to conventional techniques such as gas chromatography-mass spectrometry analysis and TBARS values. Meat samples from two suppliers were selected and packaged under the same atmosphere conditions. The fatty acid content, the physicochemical (TBARS and volatile compounds) and sensory parameters were measured. The samples from supplier 2 had a highest content of PUFA and n6 fatty acids that was related with a highest oxidation during storage. SIFT-MS and SPME-GC-MS detected a significant increase for most of the volatiles compounds analyzed during storage especially, in aldehyde compounds. High correlation coefficients between TBARS values and linear aldehydes (C3-C7) measured by both techniques were obtained and this indicates that SIFT-MS can be used to monitor lipid oxidation changes.

Real Time Detection of Aroma Compounds in Meat and Meat Products by SIFT-MS and Comparison to Conventional Techniques (SPME-GC-MS)

Financial support from MINECO (Spain) and Academy of Science of the Czech Republic for the joint project (project number 2010CZ0011) are fully acknowledged. Partial funding from AGL 2009-08787 from MINECO (Spain), PROMETEO 2012-001 (GVA, Spain) and FEDER funds and by Grant Agency of the Czech Republic (projects number 203/09/P172 and 203/09/0256) are also gratefully acknowledged.

Key Aroma Components of a Dry-Cured Sausage with High Fat Content (Sobrassada)

The key aroma components and the lipolysis in a dry cured sausage ‘Sobrassada of Mallorca from black pig’ were studied. Sobrassada was characterized by a fatty acid profile with a high content of monounsaturated fatty acids and by the generation during the curing process of polyunsaturated free fatty acids that were oxidized to generate flavor compounds. Eighty-four different volatile compounds were identified and three of them were for the first time detected in dry sausages (methyl nonanoate, 1-methyl-1H-pyrrole and 2-acetyl pyrrole). Thirty-five different aroma active zones were found. The aroma of sobrassada was not only due to compounds already detected as essential contributors in dry sausages (3-methyl butanoic acid, ethyl 3-methyl butanoate, 2, 3-butanedione and acetic acid) but also to other compounds such as ethyl octanoate, furfural, benzaldehyde, (Z)-2-nonenal, 4-methyl-phenol, delta-hexalactone, heptanoic acid, 2-pentylfuran and 2-acetyl-pyrrole which gave specific aroma notes.

Characterization of volatile compounds responsible for the aroma in naturally fermented sausages by gas chromatography-olfactometry

The objective of this study was to characterize naturally fermented dry sausages produced without the use of microbial starters and to determine which odour-active compounds are responsible for their aroma. The traditional manufacture was responsible for different chemical characteristics and consumers acceptance. The volatile compounds detected in the headspace comprised a complex mixture of volatile compounds derived from bacterial metabolism (mainly esterase activity of Staphyloccoci), spices and lipid auto-oxidation. The odour-active volatile compounds were identified using gas chromatography coupled to olfactometry (GC-O) using the detection frequency method. The aroma profile was characterized by the presence of several compounds such as acetic acid, ethyl butanoate, hexanal, methional, 1-octen-3-ol, benzeneacetaldehyde and 4-methyl-phenol. However, naturally fermented sausages were also characterized by numerous esters, both ethyl and methyl esters, which impart a wide variety of fruity notes.