Thermal inactivation of Listeria monocytogenes from alheiras,traditional Portuguese sausage during cooking

D values were calculated at 55, 60 and 65 °C for five Listeria monocytogenes isolates using alheira (traditional Portuguese sausage) food matrix as heating menstrum. z values were also calculated and combined with internal alheiras temperature profiles during cooking in multiple ways, allowed estimations of percentages of L. monocytogenes survival.Survival percentages estimations showed that except for roasting, the remaining evaluated cooking methods might not be sufficient to inactivate this foodborne pathogen in alheiras at the minimum temperature profiles. However, it is important to note that all evaluated cooking methods were able to inactivate L. monocytogenes in alheiras at their maximum internal temperature profiles.     

Comparison of the effects of sesame and Thymbra spicata oil during the manufacturing of Turkish dry-fermented sausage

Effects of sesame, Thymbra spicata oil and BHT (butylated hydroxy toluene) on the quality and safety (pH, biogenic amine, TBARS values, colour and sensory attributes) of Turkish dry-fermented sausage were investigated during the ripening periods. A sharp decrease (P < 0.05) in pH values were observed from 5.84 to about 4.40 during the first 2 days of ripening. The TBARS value and putrescine concentration in recipes were found in the following order: control (S1) > BHT (S2) > sesame oil (S4) > Thymbra spicata oil (S3). Histamine and tyramine concentrations were highest (P < 0.05) in the control recipe, while lowest (P < 0.05) in Thymbra spicata and sesame oil added recipes. The most acceptable recipes were found to be the sesame oil added recipes with respect to their highest overall sensory quality scores. The order of acceptability was found to be S4 = S3 = S2 > S1. The pH, L, b, and YI-values were not significantly changed (P > 0.05) by the addition of Thymbra spicata oil, sesame oil, and BHT. These results indicated that the most effective antioxidant was found to be Thymbra spicata oil. This study pointed out that natural antioxidants could be easily utilized in sausages to enhance quality and get safe products.     

Presence of Listeria monocytogenes in Turkish style fermented sausage (sucuk)

Turkish style fermented sausage (sucuk) is a well-known and very popular meat product produced in Turkey. The growth of Listeria monocytogenes in fermented sausage and other meat products may cause serious health problems for consumers. The aim of this study is to assess the presence of L. monocytogenes in sucuk sold in Istanbul. During the period of February 2004–January 2005, a total of 300 sucuk samples were obtained from various markets located in Istanbul and the presence of L. monocytogenes was analyzed according to “Food and Drug Administration” (FDA) method. The results were found to be positive for Listeria spp. and L. monocytogenes as 63 (21%) and 35 (11.6%) respectively.     

Microbial ecology of a small-scale facility producing traditional dry sausage

The microbial ecology of a small-scale facility producing traditional dry sausage (without addition of starter cultures) was investigated at 17 control points (12 processing surfaces and equipments samples, 5 raw materials and products samples) and at different periods: winter and spring.Technological flora (lactic acid bacteria, staphylococci/Kocuria and yeast/moulds) populations were low in processing surfaces and equipments (below 10² c.f.u/cm²), but reached a level of about 10⁶–10⁷ c.f.u/g for lactic acid bacteria and staphylococci/Kocuria and about 10⁴ c.f.u/g for yeasts/moulds in the final product. Counts of enterococci were low in most of processing surfaces and equipments and increased in the batter and the sausage-1 week; but declined after 8 weeks of ripening.Differences in temperatures of the processing facility recorded in winter and in spring influenced the hygienic quality of raw materials. Pseudomonas and Coliforms populations enumerated from raw materials in spring were about 3 log₁₀ c.f.u/g superior compared to enumeration results recorded in winter. While Pseudomonas population declined remarkably in the final product, Coliforms population remained higher. Staphylococcus aureus was undetected in spring; however in winter, its population was about 2.5 log₁₀ c.f.u/g in the final product after 9 weeks ripening. One isolate originating from the stuffing machine was identified as Listeria monocytogenes. Finally, 9 presumptive Salmonella were identified as belonging to Hafnia alvei, Providencia alcalifaciens, Proteus vulgaris, P. penneri and Morganella morganii species.These results emphasize the necessity of improving the general hygienic conditions and also technological process of sausage production in this processing facility.     

Effect of chitosan–caraway coating on lipid oxidation of traditional dry fermented sausage

Dry fermented sausage (Petrovská klobása) was coated with chitosan–caraway film. Effect of coating on fatty acid profile, lipid oxidation and sensory property of odor and taste were investigated during five months storage.At the end of storage period, sum of unsaturated and polyunsaturated fatty acids was significantly higher (p < 0.05) in coated than in control sausage.Contents of propanal and pentanal were significantly higher in the control sausage, while the rest of aldehydes content (hexanal, heptanal and octanal) did not differ between control and coated sausage.In both coated and control sausage, TBARS values content increased after two months storage and then remained unchanged until the end of storage period. Between examinated groups of sausages no significant difference was observed (p > 0.05).After two months of storage, sensory property of odor and taste did not differ between examinated groups of sausages, but at the end of storage period this value was significantly higher for coated sausage.Chitosan–caraway coated sausage showed lower intensity of lipid oxidative changes and better sensory properties for odor and taste at the end of five months storage in comparison to control.     

Microbial profile of buffalo sausage during processing and storage

A study was made on the microbial levels of buffalo sausage during preparation and storage at 4 ± 1 °C. Microbial counts in raw minced meat were, total plate count (TPC) (log cfu/g) 5.41 ± 0.25; coliforms (MPN/g) 23.2; Staphylococcus aureus (log cfu/g) 1.57 ± 0.11; yeasts and molds (log cfu/g) 2.29 ± 0.07 and lactic acid bacteria (LAB) (log cfu/g) 0.60 ± 0.20. Sausage emulsion showed similar trend in microbial counts with minimal microbial contamination during the preparation of emulsion. Cooked buffalo sausage gave the following microbial counts: TPC (log cfu/g) 3.75 ± 0.31; coliforms (MPN/g) 0.2; LAB (log cfu/g) 0.07 ± 0.01; yeast and molds (log cfu/g) 0.72 ± 0.07. S. aureus, Clostridium perfringens and Bacillus cereus were not detected in cooked sausages. These results indicate that steam cooking for 45 min followed in the study was effective in reducing the microbial counts substantially. The investigation revealed that shelf life of cooked buffalo sausage was 31 days in either vacuum or CO₂ at 4 ± 1 °C. The results indicated that spoilage of vacuum packed cooked buffalo sausage was likely due to LAB while microflora other than LAB may be responsible for spoilage of CO₂ packed cooked buffalo sausage. The study suggests that measures such as low initial microbial counts, hygienic precautions during preparation of sausage, steam cooking for 45 min, vacuum or CO₂ packing and storage at 4 ± 1 °C would control the microbial growth and provide wholesomeness and safety to the buffalo sausage.     

Effect of the use of selected starter cultures on some quality,safety and sensorial properties of Dacia sausage,a traditional Romanian dry-sausage variety

The effect of selected starter cultures (Lactobacillus sakei CECT5764 + Staphylococcus equorum SA25 or L. sakei CECT5764 + S. equorum SA25 + Lactobacillus acidophilus CECT903) on some quality, safety and sensorial characteristics of Dacia sausage, a Romanian traditional variety, was investigated. Physico-chemical parameters, microbial counts and biogenic amines during manufacture as well as the sensorial characteristics of the final products were determined both in control and in inoculated sausages.The use of starter cultures significantly (P <0.05) increased he counts of LAB and Micrococcaceae + Staphylococcaceae, and provoked an earlier drop of the pH values and the fall, even the disappearance, of the Enterobacteriaceae. The inoculated batches showed significantly (P < 0.05) lower contents of tyramine, putrescine and cadaverine and of total biogenic amines, and they received higher scores for overall acceptability when they were sensory analyzed.Results obtained in this work indicated that starter culture consisting of L. sakei CECT5764 + S. equorum SA25 + L. acidophilus CECT903 was the best culture for this type of sausage.     

Effect of usage Urtica dioica L. on microbiological properties of sucuk, a Turkish dry-fermented sausage

The effect of dried-ground Urtica dioica L. on microbiological characteristics of Turkish dry-fermented sausage (sucuk) were investigated. Dried-ground Urtica dioica L. was added to sucuk batters by the rate of 0%, 1%, 3% and 5%, and microbiological analysis were made on the 0, 3, 7, 10 and 14 days of ripening period.

According to the results, both the level of Urtica dioica L. and ripening time had a significant effects on the total aerobic mesophylic bacteria, lactic acid bacteria, Micrococcus/Staphylococcus, yeast-mould and Enterobacteriaceae counts (p<0.01). It was determined that the interactions ripening time × the levels of Urtica dioica L. had a significant effects on the counts of total aerobic mesophylic bacteria, lactic acid bacteria, Micrococcus/Staphylococcus, yeast-mould and Enterobacteriaceae (p<0.01). Enterobacteriaceae count were also found to be under the detectable level (<100 cfu/g) in sucuks (in day 14 of ripening) containing 3% and 5% Urtica dioica L.     

Changes in flavour characteristics and bacterial diversity during the traditional fermentation of Chinese rice wines from Shaoxing region

As a traditional alcoholic beverage, Chinese rice wine is quite popular for its unique flavor and high nutritional value. In this study, we investigated the changes of flavor compounds in varying stages of fermentation by HS-SPME-GC-MS and HPLC. In addition, 16s rDNA-PCR was utilized to analyze the changes of bacterial communities during fermentation of Chinese rice wine from the Shaoxing region. It was noted that the content of flavor compounds including esters, higher alcohols, amino acids and organic acids was different in varying stages of fermentation. In general, the flavor compounds of Chinese rice wine were mainly produced after pre-fermentation. The results also showed that the bacterial community structures and diversity of Chinese rice wine varied significantly during different fermentation stages, and more than 10 genera of bacteria was detected in Chinese rice wine fermentation broth. Among these specific bacteria identified in the study, Lactobacillus (the predominant genus) and Bacillus might take an active part in flavor development in Chinese rice wine. This implied that these bacteria might play significant contributions on the flavor of Chinese rice wine.     

Survey of aflatoxin B1 in helva,a traditional Turkish food,by TLC

A total of 102 helva samples consisting of 34 plain helva, 34 helva containing cacao, and 34 helva containing pistachio nuts purchased from helva-factories and supermarkets in Adana of Turkey were analysed for aflatoxin B₁ (AFB₁) by thin-layer chromatography. The detection limit of AFB₁ was 1 μg kg⁻¹. Recovery experiments were carried out with spiked samples in the range 2–10 μg kg⁻¹ of AFB₁. No AFB₁ was found in any plain helva and helva containing cacao samples. On the other hand, of 34 helva containing pistachio nuts AFB₁ was determined in eight samples. AFB₁ was found in excess of Turkish legal limit of 5 μg kg⁻¹ in 4 of 102 helva samples. This paper reports the data of the first survey for the presence of AFB₁ in helva in Turkey.     

Determination of microbiological contamination sources during Turkish white cheese production

This study has been conducted to determine the microbiological contamination sources during production of white cheese in a local dairy plant, Bursa, Turkey. Twenty nine different control points or sample types (raw milk, pasteurized milk, milk in cheese vat, curd, moulded cheese before salting, moulded cheese after salting, cheese at cold holding and vacuum packaged cheese; samples from starter culture, rennet, calcium chloride solution, brine, cheese vat, cheese cloth, polyethylene separator sheet, milk stirrer, curd cutting knife, side pressure plate, upper pressure plate, moulded cheese cutting knife, cheese tray, packaging material used during production; workers’ hands, cold room and production room air, floor, wall, and potable water) have been examined for the enumeration of total aerobic mesophilic bacteria, staphylococci, coagulase positive staphylococci, Enterobacteriaceae, enterococci, coliforms, Escherichia coli, psychrophilic bacteria, and yeast and molds.We determined: starter culture as the possible contamination source of coagulase positive staphylococci, enterococci and psychrophilic bacteria; brine and upper pressure plate as the contamination source for staphylococci; floor and packaging material as the contamination source of psychrophilic bacteria; cheese vat, cheese cloth and curd cutting knife as the contamination source of total aerobic mesophilic bacteria; cold room and production room air as the contamination sources for yeast and molds.     

Effect of fermentation temperature and must processing on process productivity and product quality in mescal fermentation

We examined the quality and production yield of mescal obtained by fermentation of traditional (including bagasse) and filtered musts at three temperatures (18, 25 and 32 °C). Fermentation temperature did not affect the concentration of methanol, higher alcohols, or dry extracts, and in all cases the product met the standards of the Mexican Official Norm for these compounds. On the other hand, the acidity of the product fell within specifications only for fermentations performed at 18 °C (either must) or 32 °C (filtered must only). Processing at the higher temperature also resulted in increased productivity, demonstrating that fermentation of filtered musts at 32 °C is a useful means of improving both the quality and throughput of mescal production.     

Survival of Enterobacteriaceae during processing of Chorizo de cebolla,a Spanish fermented sausage

Chorizo de cebolla is a popular semi-dry fermented sausage from Galicia (NW of Spain). The survival of Enterobacteriaceae was investigated in three batches of C. de cebolla (one of them hand made and the other two manufactured industrially). The maximum count of Enterobacteriaceae was obtained in each lot after 2 days of the raw sausage mix being stuffed and from then on it started to decrease until it disappeared in the fourth week of ripening in one of the batches manufactured industrially and after 6 weeks in the other. In the artisanal sausages the counts practically decreased exponentially until the third week of ripening, increasing in the following week before again decreasing until the end of ripening, though they never disappeared. Escherichia coli, Serratia odorifera and Enterobacter intermedius were the only species isolated during the curing process of the hand made sausages, E. coli being the dominant species. In the industrial ones a higher number of species were isolated, with the predominance of E. coli and Hafnia alvei.     

Study of physicochemical parameters and spontaneous fermentation during traditional production of munkoyo, an indigenous beverage produced in Democratic Republic of Congo

The evolution of physicochemical parameters and spontaneous fermentation were investigated during traditional production of munkoyo. During munkoyo preparation, starch hydrolysis by amylolytic enzymes contained in munkoyo roots was performed at temperatures above 43 °C. After 90 h, pH decreased from 6.4-6.2 to 3.7-3.6; lactic acid concentration and acidity increased respectively from 4.4-15.0 mmol l⁻¹ to 42.0-44.0 mmol l⁻¹ and 0.05% to 0.45-0.6%; alcohol content did not exceed 394 mmol l⁻¹. When the temperature dropped from 43-42 °C to 29-25 °C, in the first 15 h of fermentation, the rate of pH decrease was significant, from 6.4-6.2 to 4.1-4.0. The acidification of munkoyo was due to lactic acid, largely in the form of the d (−) lactate isomer. At temperatures around 20 °C, secondary products also contributed to the acidification of the beverage. Lactic fermentation, observed from 43 °C in the wort, was promoted by thermophilic lactic acid bacteria. Lactobacillus delbrueckii lactis was identified as the representative lactic acid bacteria. Alcohol production in munkoyo, beginning only after 15 h of fermentation, is due mainly to Saccharomyces cerevisiae.     

Characterisation of the Paio do Alentejo, a traditional Portuguese Iberian sausage, in respect to its safety

Two industrial plants, one with smoking and another without it, where no starter cultures are used, were selected in the Alentejo Portuguese region to study the characterization of “Paio do Alentejo”, a traditional Iberian dry-cured sausage. Variation of the main physico-chemical parameters (pH, a_w, chlorides, water content, total protein, fat, total ash, TVBN, L^*, a^*, b^*), fatty acids (lauric, miristic, palmitic, palmitoleic, margaric, margaroleic, estearic, oleic, linoleic, linolenic, gadoleic, heneicosenoic) and microbiological counts (total aerobic, psichrotrophic, moulds, yeasts, Lactobacillus spp., lactic acid bacteria, Micrococcaceae, Enterobacteriaceae, and Enterococci) were determined in the ingredients and throughout the processes studied to know their safety level and the possibilities to improve their control.The technological procedure (formulation, drying, smoking) that favours microbial control, cause a decrease in water content, a_w and L^*, and an increase in TVBN, fat, protein and total ash. In general terms, unsaturated fatty acids decreased and saturated fatty acids increased. Microbial growth was characterized by the predominance of Lactobacillus spp. (reaching levels of 10⁶–10⁸ cfu/g), that influences the drop of pH, followed by Micrococcaeae and the absence of microbial risks groups at the final stages of production. Portuguese Iberian dry-cured sausages have not been previously characterized as to their chemical and microbiological status in relation with safety and food control. After this study, some HACCP recommendations could be made to the producers. Future use of starters could improve their safety and control.     

Shelf-life and safety characteristics of Italian Toscana traditional fresh sausage (Salsiccia) combining two commercial ready-to-use additives and spices

The main objective of this paper was to evaluate the efficacy, in terms of safety, shelf life extension and keeping quality of different commercial ingredients, including nitrite/nitrate and spices, of fresh Italian Toscana traditional sausages. In particular, the role of spices, in the possible reduction or replacement of nitrate and nitrite, was investigated. The data evidenced the significant role of the spices on the growth reduction of deliberately inoculated Listeria monocytogenes,. The Principal Component Analyses of the microbial metabolite and sausage flavours suggested that the microbial activity was affected more by spices than by nitrite and nitrate extent.     

Kinetics of ochratoxin A destruction during coffee roasting

In the present study, Coffea arabica was artificially contaminated with spores of toxigenic Aspergillus westerdijkiae. The contaminated coffee was roasted in a vertical spouted bed roaster at four different temperatures (180 °C, 200 °C, 220 °C and 240 °C) and three different time periods (5, 8 and 12 min), in order to obtain more accurate results for the development of the kinetic model for ochratoxin A (OTA). Chlorogenic acids (CGA) content during coffee roasting was also evaluated to investigate the effect of the heat employed to destroy OTA in these health promoting compounds. Coffee treated with spouted bed roasting significantly reduced the OTA level from 8% to 98%. The spouted bed roasting proved to be a very efficient procedure for OTA reduction in coffee, and its reduction depended directly on the degree of roasting. OTA degradation during coffee roasting followed first order reaction kinetics. Using the apparent activation energy of OTA degradation and the temperature-dependent reaction rate, there was a compliance with the Arrhenius equation. This model was capable of predicting the thermal induced degradation of OTA and may become an important predicting tool in the coffee industry. The present study was also able to propose roasting conditions appropriate to destroy OTA and maintain most of the CGA at the same time.     

Modeling of heat transfer in tanks during wine-making fermentation

Temperature is one of the main factors that affect the fermentation kinetics during wine-making. We developed a thermal model to evaluate the power required to control this temperature. The model includes the changes in physico-chemical properties of the must during fermentation and the refrigeration losses to ambient from the outer surface of the tank. We used the model to run simulations and to estimate the power required to cool an industrial tank. The results were discussed considering the impact of variables such as the air speed and the air temperature. We finally validated the thermal model at the pilot scale.     

The incidence and distribution of ochratoxin A in Daqu,a Chinese traditional fermentation starter

Daqu, a traditional starter culture mainly used to produce Chinese liquor and vinegar, is spontaneously fermented by diverse bacteria, yeasts and filamentous fungi under thermophilic condition. Therefore, mycotoxins may exist in Daqu, resulting in the contamination of end-foods. Ochratoxin A (OTA), a mycotoxin produced by certain species of Aspergillus and Penicillium, is not known whether existing in Daqu. However, specific method to detect OTA as well as OTA occurrence in Daqu has not been reported so far. With this in mind, a new method was developed to detect OTA in Daqu by the combination of ultrasound-assisted solid-liquid extraction (USLE), solid phase extraction (SPE) cleanup and UPLC-MS/MS. The USLE conditions of OTA from Daqu were optimized using Plackett-Burman (PB) design coupled with Box-Behnken (BB) design. Under the optimized conditions, no matrix effects were found, and the external standard method can be used to determine OTA in Daqu. The recoveries for spiked samples were 87–106% with the relative standard deviations (RSD) < 15%. The limits of detection and quantification were respectively 0.33 and 0.41 ppb. This approach was then applied to analyze 133 Daqu samples from different geographical regions in China, including 26 low temperature-, 33 medium temperature- and 74 high temperature-type Daqu. The results showed that OTA was detected in 66 samples with a maximum concentration of 28.87 ppb in low temperature Daqu, and the OTA incidence was on increase in the order of high temperature-, medium temperature- and low temperature-type Daqu. This implied that fermentation temperature is the key factor influencing OTA occurrence in Daqu. Moreover, there may be some fungi possessing the biosynthesis ability of OTA under high temperature environment (more than 45 °C).