M.I. Cambero

Breaking strength of dry fermented sausages and their correlation with texture profile analysis (TPA) and physico-chemical characteristics

In order to assess its usefulness for monitoring textural properties of dry fermented sausages (chorizo, salchichon, salami, fuet and mini-fuet) the determination of breaking strength (BS) was evaluated. Texture profile analysis (TPA) and physico-chemical measurements (pH, aw, dry matter, fat content) were also performed. The BS determined by tensile test and TPA analysis produced complementary information that allowed these meat products to be grouped according to four different textural profiles. These profiles were characterized (p<0.05) by the values of BS, hardness, adhesiveness, cohesiveness and springiness. Multivariate analysis confirmed that BS and TPA parameters were correlated significantly (p<0.00005). On basis of these results, TPA parameters could be used to construct regression models to predict BS and therefore, to obtain a more complete textural property description of the dry fermented sausages. The resulting regression model was BS=-0.777+0.728∗adhesiveness-16881∗cohesiveness+1884.61∗springiness+0.042∗hardness (R(2)=0.634, p<0.00005).

Tensile properties of cooked meat sausages and their correlation with texture profile analysis (TPA) parameters and physico-chemical characteristics

The possibilities of using breaking strength (BS) and energy to fracture (EF) for monitoring textural properties of some cooked meat sausages (chopped, mortadella and galantines) were studied. Texture profile analysis (TPA), folding test and physico-chemical measurements were also performed. Principal component analysis enabled these meat products to be grouped into three textural profiles which showed significant (p<0.05) differences mainly for BS, hardness, adhesiveness and cohesiveness. Multivariate analysis indicated that BS, EF and TPA parameters were correlated (p<0.05) for every individual meat product (chopped, mortadella and galantines) and all products together. On the basis of these results, TPA parameters could be used for constructing regression models to predict BS. The resulting regression model for all cooked meat products was BS=-0.160+6.600∗cohesiveness-1.255∗adhesiveness+0.048∗hardness-506.31∗springiness (R(2)=0.745, p<0.00005). Simple linear regression analysis showed significant coefficients of determination between BS (R(2)=0.586, p<0.0001) versus folding test grade (FG) and EF versus FG (R(2)=0.564, p<0.0001).

Raman spectroscopy study of the structural effect of microbial transglutaminase on meat systems and its relationship with textural characteristics

Raman spectroscopy and texture analysis (TPA) studies were carried out to determine the effect of adding different levels of microbial transglutaminase (MTGase) to meat systems. This addition produced a significant (p<0.05) increase in hardness, springiness and cohesiveness in the meat systems. Raman spectroscopy analysis revealed the occurrence of secondary structural changes in meat proteins due to MTGase. Modifications in the amide I (1650-1680cm(-1)) and amide III (1200-1300cm(-1)) regions indicated a significant (p<0.05) decrease in α-helix content, accompanied by a significant (p<0.05) increase in β-sheets and turns due to the addition of the enzyme to meat systems. Significant (p<0.05) correlations were found between these secondary structural changes in meat proteins and the textural properties (hardness, adhesiveness, springiness and cohesiveness) of meat systems.

Effect of dietary linseed oil and α-tocopherol on pork tenderloin (Psoas major) muscle

The effect of linseed oil and α-tocopheryl acetate on the fatty acid composition and the susceptibility to oxidation of lipid fraction from pork tenderloin (Psoas major) muscle has been studied. Muscles were obtained from animals fed on diets with the same ingredients excepting the oil source [sunflower (C), linseed (L) and linseed and olive (1/1, w/w) (LO)] and α-tocopherol [20 (C, L and LO) or 200 (LOE and LE) mg/kg diet]. The n-6/n-3 ratio in pork tenderloin was markedly modified by dietary linseed oil administration, which was due to the increase in the C18:3n-3 (and total n-3 fatty acids) and the decrease in the C18:2n-6 (and total n-6 fatty acids) contents (P<0.05). The α-tocopherol content of tenderloin from batches LE and LOE was about 2.8 mg/kg of muscle, significantly greater (P<0.05) than about 0.7 mg/kg muscle found in tenderloin from pigs receiving C, L and LO. Dietary supplementation with α-tocopheryl acetate markedly reduced tenderloin lipid oxidation from animals fed diets enriched in n-3 fatty acids (L or LO vs LE or LOE).

Impact of feeding and rearing systems of Iberian pigs on volatile profile and sensory characteristics of dry-cured loin

The effect of growing pigs on free-range (FR) or in confinement with three different diets [acorn (A), acorn and grass (A-G) and formulated diet (FD)] on composition, volatile profile and sensory characteristics of dry-cured loin was studied. The FR, A and A-G diets, in comparison with FD, induce a higher α- and γ-tocopherol concentration, which limits the TBARs values at 24h of air exposure. Sixty volatile compounds were identified in the headspace, including 14 aldehydes, 10 hydrocarbons, eight alcohols, five ketones, four furans, four pyrazines, four sulphur compounds, three acids, three esters, three phenols, one pyridine and one pyrrole. Volatiles from amino acid catabolism stressed the difference among batches FR being the batch with the highest level of these compounds. Products from FD showed the lowest fat content and L(∗) value. FR loins obtained the highest scores for appearance, odour and flavour in the rank order test sensory analysis.

Effect of the addition of pancreatic lipase on the ripening of dry-fermented sausages — Part 1. Microbial, physico-chemical and lipolytic changes

The effect of the addition of nine different amounts (3-500 units) of pancreatic lipase on the microbial and physico-chemical parameters and lipid fractions during the ripening of dry fermented sausages has been studied. No differences between conventional and lipase-added sausages were found for pH, dry matter and water activity. The addition of lipase caused a greater accumulation of products resulting from the triglyceride breakdown, mainly diglycerides and free fatty acids (FFA). The maximum rate of lipolysis was observed during the first week of the ripening process, specially in the fermentation phase. The greater the pancreatic lipase added, the higher lipolysis observed. At the end of the ripening, the levels of total FFA were clearly higher (1·5 to 5-fold) in all lipase-added batches than in the controls. This fact gave rise to the accumulation of a great amount of FFA, which can contribute either by themselves to the flavour of the sausage or can be available as substrates for further transformations which may generate other flavour compounds.

Elimination of Listeria monocytogenes from vacuum-packed dry-cured ham by E-beam radiation.

The inactivation kinetics for Listeria monocytogenes Scott A (CIP 103575, serotype 4b) and Listeria innocua (NTC 11288) after E-beam radiation were studied in vacuum-packed ready-to-eat dry-cured ham to optimize the sanitation treatment of this product. A treatment of 1.12 kGy was calculated to reach the food safety objective according to the U.S. Department of Agriculture criterion. No irradiation treatment is necessary to meet the European Union microbiological criterion for this bacterium. No changes (at doses < or =4 kGy) in the 2-thiobarbituric acid reactive substances values and texture were observed. Dry-cured hams treated with 1 and 2 kGy had negligible sensory modifications (appearance, odor, and flavor). However, the application of 3 and 4 kGy resulted in an increase in the intensity of off-odors and off-flavors. Despite these effects, all irradiated vacuum-packed dry-cured hams treated at < or =4 kGy were deemed acceptable for trading.

Effect of the addition of pancreatic lipase on the ripening of dry-fermented sausages — Part 2. Free fatty acids, short-chain fatty acids, carbonyls and sensory quality

The effect of the addition of nine different amounts (3-500 units) of pancreatic lipase on the composition of free fatty acids (FFA), short-chain fatty acids and carbonyls, as well as the sensory quality, has been studied on dry fermented sausages. The lipase produced a greater release of all fatty acids in relation to the control sausages. The greater the pancreatic lipase content, the higher the release of these fatty acids, the most important ones being myristic, palmitoleic and oleic acids. A lower release of linoleic acid was observed, probably because of its oxidative degradation. At the end of the ripening in all lipase-added batches, a clear increase of the carbonyl content was noticed in relation to conventional sausages. No consistent changes were observed in the short-chain fatty acid fraction. In the sensory evaluation, the highest significant differences (P < 0·01) between control sausages and lipase-added batches were observed when 60 and 90 lipase units were used. According to the chemical and sensory analyses, it can be concluded that the addition of 60 and 90 units to sausages seems to be useful to enhanced the flavour of these products.

Enrichment of dry-cured ham with α-linolenic acid and α-tocopherol by the use of linseed oil and α-tocopheryl acetate in pig diets

The use of α-linolenic acid and α-tocopherol enriched pork on the fatty acids and the sensory characteristics of Spanish dry-cured hams have been studied. Five batches of hams were manufactured using the posterior legs of pigs fed on diets with the same ingredients except for the oil source: sunflower (C), linseed (L) or linseed and olive (1/1, w/w, LO). Two different α-tocopheryl acetate concentrations [20 (C, L and LO) or 220 (LOE and LE)mg/kg diet] were used. Biceps femoris and Semitendinosus/Semimembranosus muscles from hams with low polyunsaturated fatty acid n-6/n-3 ratio (less than 3) were obtained from animals fed on linseed and linseed/olive oil enriched diets. However, hams from animals fed on diets added with linseed and α-tocopheryl acetate (20mg/kg diet) (batch L) were rejected by consumers because of less acceptable sensory characteristics and higher TBARs. The remaining hams had satisfactory sensory and nutritional characteristics.

Microbial transglutaminase for cold-set binding of unsalted/salted pork models and restructured dry ham

The viability of using microbial transglutaminase (MTGase) as a cold-set binder for restructuring and manufacturing deboned dry ham (RDH) was evaluated. The influence of meat pre-treatment, preparation of the MTGase, packing system and set temperature on the binding rate and force was tested using pork models and deboned legs. The best binding parameters were obtained when meat surfaces were evenly distributed with salts (NaCl, KNO(3), NaNO(2)) and then washed with a saline solution (W), afterwards powder (P) or liquid (L) MTGase was applied, and simultaneous salting and vacuum packing (S) set at 7 degrees C were performed. The RDH manufactured following these procedures (WPS and WLS) was stable during drying and could resist the handling and production process. Binding force increased (p<0.05) during 8 weeks of drying. Scanning electron microscopy analysis showed an increase of cross-links during the drying period of RDH related to the increase in binding force.