Microbiota of sliced cooked ham packaged in modified atmosphere throughout the shelf life: Microbiota of sliced cooked ham in MAP.

Fourteen lots of cooked ham in modified atmosphere packaging (CH) were analyzed within a few days from packaging (S) and at the end of the shelf-life (E), after storage at 7 °C to simulate thermal abuse. Five more lots, rejected from the market because spoiled (R), were included in the study. Quality of the products was generally compromised during the shelf life, with only 4 lots remaining unaltered. Analysis of 16S rRNA gene amplicons resulted in 801 OTUs. S samples presented a higher diversity than E and R ones. At the beginning of the shelf life, Proteobacteria and Firmicutes dominated the microbiota, with Acinetobacter, Brochothrix, Carnobacterium, Lactobacillus, Prevotella, Pseudomonas, Psychrobacter, Weissella, Vibrio rumoiensis occurring frequently and/or abundantly. E and R samples were dominated by Firmicutes mostly ascribed to Lactobacillales. It is noteworthy the appearance of abundant Leuconostoc, negligible in S samples, in some E and R samples, while in other LAB were outnumbered by V. rumoiensis or Brochothrix thermosphacta. The microbiota of spoiled and R samples could not be clustered on the basis of specific defects (discoloration, presence of slime, sourness, and swollen packages) or supplemented additives. LAB population of S samples, averaging 2.9 log10(cfu/g), increased to 7.7 log10(cfu/g) in the E and R samples. Dominant cultivable LAB belonged to the species Lactobacillus sakei and Leuconostoc carnosum. The same biotypes ascribed to different species where often found in the corresponding S and R samples, and sometime in different batches provided from the same producer, suggesting a recurrent contamination from the plant of production. Consistently with growth of LAB, initial pH (6.26) dropped to 5.74 in E samples. Volatiles organic compound (VOCs) analysis revealed that ethanol was the major metabolite produced during the shelf life. The profile of volatile compounds got enriched with other molecules (e.g. 2-butanone, ethyl acetate, acetic acid, acetoin, butanoic acid, ethyl ester, butanoic acid, and 2,3-butanediol) mainly ascribed to microbial metabolism.

Reduction of salt in pork sausages by the addition of carrot fibre or potato starch and high pressure treatment.

The combined effect of high pressure processing (HPP) (400, 600 and 800 MPa) and carrot fibre (CF) and potato starch (PS) on low salt (1.2%) pork sausages was investigated and compared with high (1.8%) salt sausages. Sausages had a marked increase in whitening with increasing content of fibre or starch, pressure level, and process temperature. The degree of redness was mainly affected by pressure level and heat treatment. An important finding regarding salt reduction was that the use of starch or fibre had more impact on textural properties than the level of salt since Young's modulus and strain at fracture were mainly affected by formulation and HPP. Water binding capacity of low salt sausages was improved to the same level as high salt sausages with HPP and addition of CF or PS particularly by the addition of PS which produced sausages with better sensory properties than CF. The sensory analysis showed that this approach is promising for producing low salt sausages.

Synergistic cooperation of high pressure and carrot dietary fibre on texture and colour of pork sausages.

In order to investigate the synergistic cooperation between high pressure treatment (HP) and carrot dietary fibre, two formulations of pork sausages containing different percentage of carrot dietary fibre were pressurized at 500 and 600 MPa, for 1 second, 3, 6, and 9 min at 40, 50, and 60 °C. HP treatments significantly increase Young's Modulus and affect Hencky strain values. We conclude that HP processing and carrot dietary fibre markedly improved emulsion strength resulting in firm sausages. Colour changes were investigated and significant increase in L* value and decrease in a* value were found, indicating that HP, temperature, and dietary fibre can affect physico-chemical properties of the meat matrix altering the intrinsic ability to absorb or reflect light. The sensory evaluation showed that HP treatment synergistically cooperate with carrot dietary fibre improving sensorial attributes like homogeneity, creaminess, fattiness, and firmness as detected by Napping in combination with Ultra-Flash Profile.

Water properties and structure of pork sausages as affected by high-pressure processing and addition of carrot fibre.

The effects of high-pressure processing (HPP) and addition of carrot fibre on pork sausages have been studied using NMR T2 relaxometry and measurements of water-binding capacity (WBC) by centrifugation. Significant effects of temperature (raw, 40, 50, or 60 °C), holding time (1s, 3, 6, or 9 min), and addition of carrot fibre on the distribution and mobility of water were found. However, the effect of carrot fibre could not be explained by structural changes in the sausages when examined by confocal laser scanning microscopy (CLSM). Correlations between T2 relaxation measurements and WBC determined by centrifugation revealed that T2 relaxation times were able to explain more than 90% of the variation in WBC for both non-pressure and pressure-treated sausages. However, only 49% of the variation was explained for pressure-treated sausages with carrot fibre, indicating that combining addition of fibre and high pressure treatment causes non-coherent changes in T2 NMR relaxation times.