Shelf life of packaged sliced dry fermented sausage under different temperature

Lipid Hydrolysis, Oxidation, and Fatty Acid Formation Pathway Mapping of Synergistically Fermented Sausage and Characterization of Lipid Mediating Genes

Starter cultures play a significant role in lipid hydrolysis, prevention of lipid oxidation, and synthesis of fatty acid in fermented sausage, enhancing product quality. In this study, five synergistic bacterial strains were used, including Pediococcus pentosaceus (B-3), Latilactobacillus sakei DLS-24 (D-24), Latilactobacillus acidophilus DLS-29 (D-29), Lactiplantibacillus pentosus (B-1), and Lactiplantibacillus plantarum (B-2). Sausage B1B3D24 gave the highest free fatty acid with 39.45 g/100 g at 45-Day. Based on 2-thiobarbituric acid reactive substance, B2B3 contains 112.68 MDA/kg. Lipoxygenase activity displays the lowest in B1B3D24 with 0.095 μmol/min·mg followed by B2B3 with 0.145 μmol/min·mg. B1B3D24 contains 11.35 g/kg of monounsaturated fatty acid with the highest content in eicosenoic acid (C20:1) and palmitoleic acid (C16:1). The fatty acid synthesis pathway in B1B3D24 contains an active positive interaction with PUFA to increase the isotopomers of ω-3 and ω-6 fatty acids. In addition, lipid mediating genes in B1B3D24 show the highest counts in fatty-acid synthase, carbonyl reductase 4, 3-oxoacyl-[acyl-carrier-protein] synthase III, hydroxysteroid 17-beta dehydrogenase 8, and acetyl-CoA carboxylase.

Evaluation of vacuum packaging for extending the shelf life of Sardinian fermented sausage

Salsiccia sarda or Sardinian fermented sausage is a traditional dry-fermented sausage included in the list of traditional food products of Sardinia (Italy). At the request of some producing plants, the possibility of extending the shelf life of the vacuum-packed product up to 120 days was evaluated. Manufacturing of 90 samples, representing 3 different batches of Sardinian fermented sausage was carried out in two producing plants (A and B). In the packaged product and subsequently every 30 days for four months (T₀, T₃₀, T₆₀, T₁₂₀), the following analyses were conducted on all samples: physicochemical characteristics, total aerobic mesophilic count, Enterobacteriaceae count, detection of Listeria monocytogenes, Salmonella spp., mesophilic lactic acid bacteria, and coagulase-positive Staphylococci. Moreover, surfaces in contact and surfaces not in contact with food were sampled in both producing plants. Sensory profile analysis was also performed for every analysis time. At the end of the extended shelf life, pH values were equal to 5.90±0.11 (producing plant A) and 5.61±0.29 (producing plant B). Water activity mean values at T₁₂₀ were 0.894±0.02 (producing plant A) and 0.875±0.01 (producing plant B). L. monocytogenes was detected in 73.3% (33/45) of the samples from producing plant A, with mean levels of 1.12±0.76 log₁₀ CFU/g. In producing plant B, L. monocytogenes was never detected. Enterobacteriaceae were detected in 91.1% (41/45) of samples in producing plant A with mean values of 3.15±1.21 log₁₀ CFU/g, and in 35.5% (16/45) samples in producing plant B samples with mean values of 0.72±0.86 log₁₀ CFU/g. Salmonella and Staphylococcus aureus were never detected. Regarding environmental samples, the sites that were most contaminated by L. monocytogenes were the bagging table (contact surface) and processing room floor drains (non-contact surface) with a prevalence of 50% each (8/16 positive samples for both sampling sites). Sensory analysis results showed that at T₃₀ the overall sensory quality was at its highest;moreover, the visual-tactile aspect, the olfactory characteristics, the gustatory aspects, and the texture showed significant differences in samples throughout the shelf life, with a decreased intensity at 120 days of storage. Overall, the quality and sensory acceptance of the vacuumpacked Sardinian fermented sausage was not affected until 120 days of shelf-life. However, the possible contamination by L. monocytogenes calls attention to the hygienic management of the entire technological process. The environmental sampling was confirmed as a useful verification tool during control.

Modelling desorption isotherm for durable meat products

The desorption isotherms of two durable meat products (sample 1 - durable fermented meat product and sample 2 - unheated durable meat product) by Dynamic Dewpoint Isotherm (DDI) at 20, 25, and 30 °C and Saturated Salt Slurry (SSS) method at 20 °C has been studied. The data acquired from these measurements for 7 models (GAB, DLP, Henderson, Chin, Smith, Oswin, Halsey) were used and statistically evaluated. Based on our collected data, the most suitable model for these types of durable meat products is the DLP model. For the DDI method, DLP model (20–30 °C) reached the R² = 0.999, P value 3.48–4.22 of sample 1 and R² = 0.999, P value 1.51–3.24 of sample 2. For SSS method DLP model (20 °C) reached R² = 0.999, P value 4.23 of sample 1 and R² = 0.998, P value 3.68 of sample 2. The most commonly used GAB model according to statistical treatment was very accurate only for the DDI method, GAB model (20–30 °C) reached R² ≥ 0.994, P value 1.93–7.12 of sample 1 and R² = 0.999, P value 1.76–5.54 of sample 2. In general, for DDI method for both samples have models (DLP, GAB, Halsey, Henderson, and Oswin) a P value of less than 10% for all three measured temperatures. For the SSS method, only the DLP and Henderson models are below 10% for both samples. It has been verified that the DDI method is a suitable and accurate method for measuring desorption isotherms for durable meat products.

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A new Dynamic Dewpoint Isotherm and Saturated Salt Slurry method were compared.

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Technological solution for a new type of durable meat product was designed.

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A new Dynamic Dewpoint Isotherm was more accurate than Saturated Salt Slurry method.

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The new DLP model best fits for durable meat products than commonly used models.

Effect of ultrasonication and vacuum impregnation pretreatments on the quality of beef marinated in onion juice a natural meat tenderizer

This study aimed to determine the effect of ultrasonication (US) and vacuum impregnation (VI) pretreatment techniques applied for the improvement of tenderness on the quality of beef (Longissimus dorsi) traditionally marinated (TM) in onion juice by immersion. TM conditions were 1:5 meat to marinade ratio, final NaCl concentration of 9% (w/v), 4.3 °C and 24 h. US and VI pretreatments significantly (P < 0.05) improved the marinade uptake, but did not alter the lightness (L*) values of beef samples compared to TM. US for 60 min and VI for 40 min pretreatments reduced the hardness of beef by 28.25 and 21.62%, respectively, compared to TM. US and VI pretreatments significantly (P < 0.05) reduced tyramine levels of uncooked and marinated beef samples. Marination in onion juice was found to reduce the lipid oxidation level of beef and increase the general liking score in the sensorial evaluation. Onion juice can be used as a natural marinade for the traditional marination of beef with the help of ultrasonication and vacuum impregnation pretreatments.

Effect of Storage Conditions on Microbiological Characteristics, Biogenic Amines, and Physicochemical Quality of Low-Salt Fermented Fish

ABSTRACT

The present study was conducted to evaluate the effects of long-term storage at various temperatures (4, 25, and 35°C) on flavor and microbiological and physicochemical qualities of traditional Chinese low-salt fermented fish (Suanyu). Food spoilage and pathogenic bacteria (coliforms, Pseudomonas, and Salmonella) were inhibited during the 90 days of storage at all temperatures. Lactic acid bacteria, yeast, and total viable bacteria counts of samples stored at 35°C were reduced sharply, whereas other parameters were stable. Compared with refrigerated storage (4°C), higher storage temperatures (25 and 35°C) accelerated moisture migration, lipid oxidation, and proteolytic degradation. Storage time had a greater effect than storage temperature on the increase of volatile compounds in Suanyu. Refrigerated storage was better than higher storage temperatures (25 and 35°C) for maintaining the odor quality of Suanyu during the storage period. Total biogenic amine concentrations in all samples were ≪200 mg/kg. Suanyu can be consumed safely during 90 days of storage based on the levels of spoilage and pathogenic bacteria and concentrations of biogenic amines, but refrigerated storage effectively slows down the microbial and physicochemical changes, resulting in better organoleptic quality. The results of this study will be useful for processors controlling the safety and quality of fermented fish during transport and storage.

HIGHLIGHTS

Contribution of surface application of chitosan-thyme and chitosan-rosemary essential oils to the volatile composition, microbial profile, and physicochemical and sensory quality of dry-fermented sausages during storage

The effect of chitosan (C), chitosan enriched with thyme (CT) or rosemary (CR) essential oils, and potassium sorbate (PS) against superficial fungal growth was investigated in fermented sausages during 3 months of storage at 4 °C. For control groups, distilled water (DW) and acetic acid (AA) were used. PS, C, CT and CR treatments inhibited fungal growth on casings while they resulted in lower Gram(+) catalase(+) cocci, Enterobacteriaceae, mold and yeast counts in sausages. Lower TBARS values were determined for CT and CR (p < .05). A total of 44 and 64 volatile compounds were identified in sausages and casings, respectively. Sausages coated with C, CT or CR had acceptable sensory attributes at the end of storage; however, DW and AA groups were rejected in the second and third month (p < .05), respectively, due to intense fungal growth which resulted in sensory defects.

Influence of Storage Temperature and Packaging on Bacteria and Yeast Viability in a Plant-Based Fermented Food

Optimization of food storage has become a central issue for food science and biotechnology, especially in the field of functional foods. The aim of this work was to investigate the influence of different storage strategies in a fermented food product (FFP) and further determine whether the regular storage (room temperature (RT) and standard packaging (SP)) could be refined. Eight experimental conditions (four different temperatures × two packaging) were simulated and changes in FFP's microbial ecology (total bacteria, lactic acid bacteria (LAB), and yeasts) and physicochemical characteristics (pH and moisture content (MC)) were determined following 1, 3, 6, and 12 months. All conditions tested showed a decline in microbial content due to the effect of the temperature, 37 °C being the most detrimental condition, while -20 and 4 °C seemed to be better than RT in some parameters. Vacuum packaging (VP) only had a major effect on MC and we found that VP preserved greater MC values than SP at 3, 6, and 12 months. The correlation analysis revealed that total bacteria, LAB, and yeasts were positively associated, and also both pH and MC showed a correlation. According to our results and with the purpose to maintain the load of viable microorganisms, we observed that the best storage conditions should contemplate SP and freezing or cooling temperature during a period no longer than 3 months.

The Impact of Residual O2, Temperature, and Light at Display on Sensory Attributes of Sliced, Packaged Salami

The aim of the study was to examine if small amounts of oxygen (O2) causing discolouration of salami exposed to light in the grocery store also cause adverse changes in the flavour and odour sensory profile. Sensory properties of packaged sliced salami under different temperatures (4, 20°C, and 23°C), two lights sources (LED and fluorescent), and a low level of residual O2 in the headspace were evaluated. The experiment consisted of nine series, which were sensory-assessed after 3 and 6 days of display. A combination of light exposure and residual O2 causing discolouration resulted in substantial off-flavour and off-odour of the displayed salami, both on the upper slice exposed to light and the middle slice in the stack with no direct light exposure. Samples from all other series without O2 and those displayed in various light or stored in darkness showed no changes in quality compared with control samples stored in darkness. Temperature at display did not affect sensory attributes in the series without O2 in the headspace. Sensory results from 3 to 6 days display were similar. To minimize quality defects and food waste, producers and retailers are advised to store packages of sliced salami in darkness until nearly all residual O2 is consumed internally by the product before placing the packages upon light in the counter.

Microbiological and Sensory Characteristics of Mould-Ripened Salami under Different Packaging Conditions

The preservation of mould-ripened salami was investigated during 48 days at 19-20 °C under different packaging conditions: (i) high barrier film filled with air, 100% N₂ or under vacuum, (ii) biaxially oriented polypropylene film, (iii) microperforated polyethylene film and (iv) unpackaged. Sensory, texture profile, physicochemical and microbiological analyses were performed. Fungal quantification revealed two data groups. In group 1 (consisting of salami in microperforated polyethylene film, biaxially oriented polypropylene film and unpackaged) the conidium viability was relatively constant. In group 2 (salami preserved in high barrier film filled with air, 100% N₂ or under vacuum) the conidium viability decreased due to the absence of oxygen and the high carbon dioxide volume fraction. SEM micrographs showed micromorphological changes in fungal structure; microperforated polyethylene film, biaxially oriented polypropylene film and unpackaged conditions preserved the conidial morphology, while high barrier film filled with air, 100% N₂ or vacuum conditions collapsed the hyphae and most of the conidia. Salami packed in microperforated polyethylene film and biaxially oriented polypropylene film showed the most acceptable organoleptic characteristics and lower hardness and chewiness values after packaging.

Shelf-Life of Boiled Salted Duck Meat Stored Under Normal and Modified Atmosphere

The objective of this study was to investigate the physicochemical properties and changes in the microbial counts of boiled salted duck (BSD) meat packed under various conditions. BSD meat was stored under normal atmosphere (C) and two modified atmosphere packaging (MAP) conditions: M1 (N₂ , 100%) and M2 (CO₂ /N₂ , 30%/70%) at 4 °C. Microbiological quality, pH, redness, lipid oxidation, headspace gas composition, and water activity of BSD meat were measured. The results showed that the time to reach the maximum acceptable total viable counts (TVC, 4.9 log CFU/g) was 12, 18, and 21 d in C, M1, and M2 samples, respectively. Significant difference in the redness values was observed in all treatments during storage. The redness value of C group was significantly lower than that in M1 and M2 groups at the end of storage. The thiobarbituric acid-reactive substances (TBARS) values under MAP were 0.24 to 0.26 mg MDA/kg meat at the end of storage, lower (P < 0.05) than that in C group (0.78 mg MDA/kg meat). The water activity in M2 group was the lowest among all 3 groups. The CO₂ concentration in M2 decreased significantly during storage. Our study demonstrates that packaging with 30% CO₂ and 70% N₂ (M2) could extend the shelf-life of BSD meat to 21 d during storage at 4 °C, suggesting that MAP can be a practical approach to extend the shelf-life and maintain the quality of BSD products.

PRACTICAL APPLICATION

This study evaluated the application of MAP for a cooked duck product. Our results showed that MAP can be utilized to extend the shelf-life. This technology may be used for preservation of other cooked meat products.

Determination of critical levels of residual oxygen to minimize discoloration of sliced packaged Norwegian salami under light display

Discoloration of sliced packaged salami is contributing to rejection of the product, food waste and economical loss. A combination of residual O₂ in the headspace of packages and light is causing photooxidation and deterioration of colour. The aim of this study was to establish maximum tolerable concentrations of residual O₂ in packages of salami slices with 100% N₂ under light display at 4 and 20°C. Salami sausages had variable inherent O₂ consumption rate. Storage of salami in 1% O₂ in darkness did not induce discoloration. The upper limits for O₂ for avoiding discoloration under light were variable in the range 0.1-1.0%, depending on temperature and type of salami. Display at 20°C increased the rate of O₂ depletion compared to 4°C. To minimize discoloration, sliced and packaged salami should be stored in darkness at approximately 20°C until the level of residual O₂ is reduced below a critical limit.