The effect of different cooking procedures on microbiological and chemical quality characteristics of Tekirdağ meatballs

In this research, the effects of different cooking processes (grilling, oven, and microwave cooking) on microbial flora and chemical composition of the raw and cooked meatballs as consumed in Tekirda? were investigated. Microbial flora of the raw meatballs was as follows: total bacteria, 6.02 x 10(6) cfu/g; psychrophilic bacteria, 1.3 x 10(5) cfu/g; yeast and mould, 2.4 x 10(5) cfu/g; coliforms, 1.1 x 10(5) cfu/g; Escherichia coli, 1.0 x 10(2) cfu/g; total staphylococcae, 3.3 x 10(2) cfu/g; Staphylococcus aureus, 85 cfu/g. While Salmonella was found in only one sample, none of the samples contained Clostridium perfringens. The cooking processes clearly decreased the microbial flora (2-3 log cycles in grilling (71 degrees C) and oven-cooked (79 degrees C), 3-4 log cycles in microwave (97 degrees C) heating) of the meatballs. However, because of the crust formation and high moisture losses from the meatball surface in microwave heating, some sensorial defects were observed in the final product. Also, fat and moisture losses were higher in microwave cooking compared to the other cooking processes. In conclusion, it is advised to use slightly higher temperatures than used in the grilling or conventinal cooking procedures to increase microbial quality of the meatballs studied in this research.     

Changes of microbiological quality in meatballs after heat treatment

The effects of different cooking processes (grilling, oven and microwave cooking) on the microbial flora of the raw meatballs inoculated with E. coli O157:H7 at the level 2×10⁴ cfu/ml were investigated. The meatballs were stored at 4 °C. The flora of the raw meatballs is described in this paper. While Salmonella was found in each sample, none of the samples contained C. perfringens or E. coli O157:H7. The processes of grill cooking or microwave cooking decreased the microbial flora by 2–3 log cycles. E. coli O157:H7 was completely destroyed by all cooking methods. E. coli O157:H7 count of the raw meatball samples increased for 1.5 log cycles at the end of storage compared to beginning.     

EFFECT OF PROCESSING ON BACTERIAL POPULATION OF CUTTLE FISH AND CRAB AND DETERMINATION OF BACTERIAL SPOILAGE AND RANCIDITY DEVELOPING ON FROZEN STORAGE

Processing techniques like cooking and freezing exhibited significant (P < 0.001) reduction in the bacterial load of cuttlefish, Sepia pharaonis, and marine crab, Portunus pelagicus. Raw cuttle fish had 2.4 × 10⁷ cfu/g which on cooking reduced to 9.7 × 10⁶ cfu/g. Freezing reduced the bacterial load further as cooked frozen product had only 9.9 × 10⁴ cfu/g. Similarly, raw crab had 2.6 × 10⁷ cfu/g which on cooking reduced to 6.5 × 10⁶ cfu/g. A further reduction in bacterial load was seen after freezing as cooked frozen crab exhibited only 7.3 × 10⁴ cfu/g. Escherichia coli and Staphylococcus aureus were present in the limit of acceptability for fish and fish products. Salmonella typhimurium and Vibrio cholerae were absent even in raw stage. Biochemical analysis performed on stored frozen products of cuttle fish and crab exhibited a significant (P ≤ 0.05) increase in bacterial spoilage and rancidity with increasing days of storage. Total volatile base nitrogen, trimethylamine, thiobarbituric acid and free fatty acid contents in frozen products of cuttle fish and crab increased significantly with 120 days of frozen storage.     

Efficacy of Combined Sous Vide‐Microwave Cooking for Foodborne Pathogen Inactivation in Ready‐to‐Eat Chicory Stems

There is a variety of different food processing methods, which can be used to prepare ready‐to‐eat foods. However, the need to preserve the freshness and nutritional qualities leads to the application of mild technologies which may be insufficient to inactivate microbial pathogens. In this work, fresh chicory stems were packed under a vacuum in films, which were transparent to microwaves. These were then exposed to microwaves for different periods of time. The application of sous vide microwave cooking (SV‐MW, 900 W, 2450 MHz), controlled naturally occurring mesophilic aerobic bacteria, yeasts and molds for up to 30 d when vacuum‐packed vegetables were stored at 4 °C. In addition, the process lethality of the SV‐MW 90 s cooking was experimentally validated. This treatment led to 6.07 ± 0.7 and 4.92 ± 0.65 log cfu/g reduction of Escherichia coli and Listeria monocytogenes inoculated over the chicory stems (100 g), respectively. With an initial load of 9 log cfu/g for both pathogens, less than 10 cfu/g of surviving cells were found after 90 s cooking. This shows that short‐time microwave cooking can be used to effectively pasteurize vacuum‐packed chicory stems, achieving >5 log cfu/g reduction of E. coli and L. monocytogenes.     

Effect of Cooking Rates in Electric or Microwave Oven on Cooking Losses and Retention of Thiamin in Broilers

A study was conducted to determine the effect of two microwave oven and two electric oven cooking rates on retention of thiamin and cooking losses with broiler chickens. Thiamin was determined by a microbiological turbidimetric assay of raw and cooked meats. Broilers cooked in the microwave oven retained more thiamin than broilers cooked in the electric oven. There was no difference in thiamin retention between broilers cooked in the microwave oven at 800 and 1600 watts. Broilers cooked in the electric oven at 204°C retained more thiamin than broilers cooked at 121°C. Broilers cooked in a 1600 watt microwave oven had the greatest weight loss. No difference in weight loss occurred between broilers cooked in an 800 watt, 121°C or 204°C oven.     

Effects of cooking methods on the proximate,mineral and fatty acid composition of European eel (Anguilla anguilla)

The influence of microwave cooking and traditional cooking methods such as baking, grilling and frying on the nutritional composition of eels (Anguilla anguilla) was studied. All methods reduced moisture and increased the protein and fat content. Although the potassium and sodium content of fish cooked by different methods decreased significantly (P = 0.000), the calcium and magnesium content increased. The zinc content of the fish was not affected by cooking. The manganese and iron content significantly increased only in fried fish. The copper content was increased by grilling and microwave cooking. The proportion of saturated fatty acids and monounsaturated fatty acids in cooked fish decreased. Omega‐3 polyunsaturated fatty acids were increased by all cooking methods. The grilling and microwave‐cooking methods were the most suitable considering the n3/n6 ratio and eicosapentaenoic acid levels. The increase in the docosahexaenoic acid level of fried fish enhanced its nutritional value.     

Fate of Listeria monocytogenes and Aeromonas hydrophila on Catfish Fillets Cooked in a Microwave Oven

Channel catfish fillets were inoculated with SJ lo⁶ cell/cm² each of Listeria monocytogenes and Aeromonas hydrophila and cooked in a microwave oven to internal temperatures of 55, 60, and 70°C. The fillets were either left uncovered or covered with polyvinylidene chloride films during cooking. A. hydrophila populations were reduced to nondetectable levels on covered fillets cooked to 70 °C. At 60 °C, L. monocyrogenes populatoins were reduced by = 4 logs for covered and by 2 logs for uncovered fillets. Covering fillets increased lethality at each temperature; however, some pathogens could survive at < 60 °C.     

Influence of Rapid Cooking Methods on the Survival of Trichinella spiralis in Pork Chops from Experimentally Infected Pigs

Pork chops (1.3, 2.5 or 3.8 cm thick) cooked to an internal temperature of 17 or 77°C by conventional oven, convection oven or flat grill contained no motile trichinae, whereas chops cooked to 66°C sometimes contained motile trichinae. Chops cooked by either charbroil or deep fat fry and pretreated in a microwave oven sometimes had motile trichinae even after cooking to an end point of 77°C. Chops, which had been frozen for 18 hr at -23°C and were thawed by microwave to 0°C then deep fat fried to an end point temperature, sometimes had infectious trichinae as confirmed by tests with rats and mice. Additional research is underway to verify the thermal death times and temperatures for T. spiralis larvae.     

Lipid characteristics in cooked, chill-reheated fillets of Indo-Pacific king mackerel (Scomberomorous guttatus)

Slices of Scomberomorous guttatus cooked by four different methods (microwave cooking, grilling, steaming and shallow fat frying) were kept chilled at 5 °C for 2 days, reheated by microwave and then evaluated for the changes in the lipid characteristics. The total lipid content for raw sample was 6.0 g/100 g which consist of 49.4 g/100 g saturated (SFA), 6.9 g/100 g monounsaturated (MUFA) and 43.8 g/100 g polyunsaturated fatty acids (PUFA). Upon cooking, the total lipids changed to about 7 (microwave), 11 (grilling), 5 (steaming) and 10 g/100 g (shallow fat frying). These changes are significant, with the exception of steam cooking. Cooking did not significantly affect the percentage of NPL, PL, SFA, MUFA and PUFA in the samples. Frying resulted in the change of the SFA/PUFA ratio more than other cooking methods. A significant (P < 0.05) decrease in the content of EPA was only found in the fried samples. A significant (P < 0.05) decrease in the content of DHA in all cooked samples were also obtained. The n-6/n-3 ratio did not change significantly in all cooked and reheated samples, except for shallow fat fried. Reheating did not significantly affect the NPL and PL contents of the fillets, except for microwave cooked samples. Cooking increases the FFA, PV and TBA of samples; reheating enhances the increase.     

Effect of cooking procedures on tylosin residues in chicken meatball

Most information about drug residues is related to their concentrations in raw products. The objective of this study was to assess the effects of various microwave and boiling treatments on the stability of different concentrations of tylosin in chicken meatballs. The chicken meatball samples (75 g) were prepared and fortified by 3 concentrations of tylosin (100, 200 and 300 μg kg^?1) and were cooked by boiling (100 °C for 10, 20, 30 min) and microwave procedure (power 450 W for 1, 1.5 and 2 min). The tylosin content was measured in raw and cooked samples through the use of high performance liquid chromatography. The microwave and the boiling process significantly reduced the tylosin. In both procedures, there were negative correlations between the length of cooking time and the reduction percentage of tylosin. In addition, tylosin reduction percentage in chicken meatball cooked by boiling depended on its concentration in uncooked samples. There was a relationship between tylosin reduction percentage and the increase in the internal temperature and weight loss during the cooking process. The results of this study indicate that tylosin residues in the food are decreased during the cooking process. Thus, given that a food product is cooked to be consumed, the surveillance of data obtained from tylosin measurement in the raw tissues samples could not be considered as consumers’ exposure to tylosin via dietary intake.     

Listeria monocytogenes Inactivation in Turkey Rolls and Battered Chicken Nuggets Subjected to Simulated Commercial Cooking

Cured and uncured turkey rolls inoculted with 10⁷Listeria monocytogenes CFU/g were vacuum packaged and cooked to internal temperatures of 68°C and 74°C, respectively, in a steam-injected chamber. Samples were stored up to 15 wk at 4°C. Battered chicken nuggets were also inoculated internally with about 10⁷L. monocytogenes CFU/ g. Nuggets enclosed in bags were cooked under moist heating conditions in a convection oven to an internal temperature of 71°C. Nuggets were flushed with 30% CO₂, 70% N₂ atmosphere and sealed. Chicken nuggets were stored at 4°C up to 30 days. No Listeria monocytogenes were recovered from the cooked products suggesting that similar commercial processes are adequate to reduce populations of L. monocytogenes below detection limits.     

Effects of different cooking methods on the mineral contents of wild and farmed sea bream (Sparus aurata)

The effects of different cooking methods (steaming, boiling, oven cooking, grilling, frying in olive oil, frying in soybean oil, frying in corn oil and frying in sunflower oil) on mineral contents (Ca, Mg, K, Na, Fe, Zn, Cu and Mn) of wild and farmed sea bream (Sparus aurata) were determined. The moisture rate decreased significantly (P < 0.05) after boiling, grilling, oven cooking and frying but remains stable after steaming. The fat content increased with different frying treatments. The Ca, Mg, Na, K and Zn contents of wild and farmed sea bream cooked by almost all methods significantly decreased (P < 0.05). The Cu content in grilled wild and farmed sea bream increased significantly (P < 0.05). Losses of mineral content in fried sea bream were higher than those of fish cooked by other methods. On comparing the raw and cooked fish, the results indicated that cooking had considerable effect on the mineral contents.     

Effect of Steam-Assisted Hybrid Cooking on Textural Quality Characteristics,Cooking Loss,and Free Moisture Content of Beef

Semitendinosus muscles were cooked in a steam-assisted hybrid oven and also convection ovens at three different oven temperatures (180, 210, and 240°C) until three different end point temperatures [65°C (medium-rare), 72°C (medium), 80°C (medium-well)] were reached. Textural properties of cooked beef were investigated by the Warner Bratzler shear test and texture profile analysis. Cooking loss and free moisture content of muscle tissue was determined for each cooking condition. In addition, sensory analysis was carried out in order to compare with the instrumental results and correlations between instrumental texture parameters and sensory results. Steam-assisted hybrid oven cooking of beef resulted in a tougher texture, higher cooking loss, and lower free moisture content than convection cooking. High correlation coefficients (r² > 0.70) were observed between instrumental texture measurements and sensory results for all ovens, especially in terms of tenderness. The free moisture content and adhesiveness values were also correlated well with juiciness (r² > 0.70) for all oven types.     

Innovative Cooking Techniques for Improving the Overall Quality of a Kailan-Hybrid Broccoli

The microbial, physical, sensory and nutritional quality of boiled (vacuum and conventional), steamed, pressure cooked, sous vide, microwaved (sous vide and conventional), deep-fried (vacuum and conventional) and grilled kailan-hybrid broccoli (Bimi®) after cooking was studied. Sous vide microwaving greatly decreased microbial counts, achieving very low psychrophilic and enterobacteria counts (1.1 and 0.2 log CFU g^?1, respectively). Vacuum boiling and sous vide reduced the stem broccoli firmness by approximately 54–58 %, reaching a pleasant and moderate softening. Sous vide, grilling and steaming induced the lowest stem colour changes. Generally, all cooking treatments showed a good overall sensory quality. The total phenolic content (1,148 mg CAE kg^?1 fw) usually increased after cooking, with microwave and grilled treatments registering the highest increases up to 2-fold. Commonly, the total antioxidant capacity (296.6 mg AAE kg^?1 fw) increased after cooking by sous vide, microwaving and frying treatments registering the highest increments, by approximately 3.6-fold. Generally, the cooking process reduced the initial vitamin C content, with vacuum and conventional boiling showing the lowest and highest losses with 27 and 62 %, respectively, while vacuum deep frying preserved the initial value (1,737 mg kg^?1 fw). As a main conclusion, the studied grilling and vacuum-based cooking treatments resulted in better microbial quality, colour, stem firmness and sensory quality than the remaining ones. This maintained or even improved the total antioxidant content of the new kailan-hybrid broccoli studied.     

Effect of warm,chlorinated water on the microbial flora of shredded iceberg lettuce

An optimization technique was used to determine suitable times of exposure and temperatures for maximum destruction of microorganisms in shredded iceberg lettuce dipped in warm, chlorinated (100 μg/ml) water in a model system. Shredded lettuce washed for 3 min at 47°C and packaged in high oxygen transmission rate (6000–8000 cc m² 24 h) bags maintained an acceptable appearance after 7 days in storage at 1±1°C. Initial microbial loads were reduced by approximately 3 log cfu g⁻¹ in lettuce washed in chlorinated water at 47°C, and 1 log cfu g⁻¹ at 4°C. Pilot plant scale studies confirmed observations in the model system. The microbial flora of shredded lettuce packaged in the raw state and after a 3 min wash in 100 g ml⁻¹ chlorine at 4 or 47°C was dominated by psychrotrophic bacteria, particularly species of Pseudomonas, throughout the storage period. Numbers of these microorganisms were significantly lower than in raw lettuce or lettuce washed at 4°C until the 15th day in storage. Gas composition inside the bags was not affected by the washes.     

Destruction of Trichinella spiralis During Cooking

Center cut chops (longissimus dorsi), 2.5 cm in thickness, from 31 pigs experimentally infected with Trichinella spiralis larvae and containing 37 ± 5 larvae per gram were cooked to a final internal temperature of 66, 71, 77 or 82° C by one of eight methods to determine their efficacy in killing encysted larvae. The results indicate that with the time and temperatures used in this study, some rapid methods of cooking pork chops that involved the use of a microwave oven did not completely destroy T. spiralis larvae at 77 or 82° C. The data also showed that cooking pork chops to an internal temperature of 77° C in the conventional oven, convection oven, flat grill, charbroiler or deep fat gryer did inactivate encysted T. spiralis larvae in pork chops.     

EFFECTS OF MICROWAVE COOKING ON FISH QUALITY

Changes in tenderness, unit proteolytic activity, protein denaturation and fatty acid content of trout (Onchorhyncus mykiss) cooked in microwave oven for different time-power combinations were studied and the relationship between protein denaturation and textural changes was investigated. Trout was cooked in the microwave oven at 20, 40 and 60% powers for 10, 20, 30, 40 s. As a control uncooked fish was used. Proteolysis was controlled by using microwave energy. Texture degradation due to proteolytic enzymes was reduced as microwave power increased. As cooking time and/or power of the microwave oven increased, proteolytic activity decreased which was a sign of the increase in enzyme inactivation. A correlation was found between the variation of texture and proteolytic activity (r = 0.973). It was observed that proteolytic enzymes were effective especially on myosin. Most of the fatty acids were not destroyed during microwave cooking. The optimum cooking conditions in microwave oven were determined as 60% power for 20 s of cooking time.     

Destruction of Pathogenic Bacteria in Turkeys Roasted in Microwave Ovens

Whole turkeys inoculated with Salmonella typhimurium, Staphylococcus aureus, or Clostridium perfringens were cooked in a microwave oven (2450 MHz) to an end-point temperature of 76.6°C. The cooking procedure did not completely eliminate any of the three pathogenic bcteria from the turkeys. The extent of survival of C perfringens on the cooked unstuffed turkeys was proportional to the number of spores in the initial inoculum. Similar results were observed when turkeys stuffed with inoculated stuffing were cooked in microwave ovens. Cooking in brown-in-bags increased the destruction of C. perfringens and S. typhimuriun in unstuffed turkeys even though the end-point temperature was only 68.3°C.     

Thermal inactivation of Salmonella on chicken wings cooked in domestic convection and air fryer ovens

Chicken wings are among the most popular poultry products for home and foodservice consumption. Poultry products must be handled and cooked safely to decrease the risk of foodborne salmonellosis for consumers. This study aims to validate the use of domestic appliances (convection and air fryer ovens) for the thermal inactivation of Salmonella on chicken wings. Wings (n = 3, 46.5 ± 4.3 g) were inoculated with a five-strain cocktail of Salmonella (ca. 8 log₁₀ CFU/wing) and cooked in a convection oven (179.4°C) or an air fryer (176, 190, or 204°C) for 2, 5, 10, 15, 20, 22, or 25 min. Thermocouples recorded temperature profiles of wings and appliances. Salmonella counts were determined on XLD agar for rinsates (100 ml/sample), and rinsates were enriched to recover bacteria below the limit of quantification. The recommended internal cooking temperature (73.8°C) was achieved after a range of 7.5 to 8.5 min in both appliances. Salmonella counts were reduced by 6.5 log₁₀ CFU/wing when this temperature was achieved. Cumulative lethality (F-value) calculations predicted a 9-log reduction after 7.0 to 8.1 min of cooking. However, sample enrichments tested positive for Salmonella for all cooking times below 22 min. Ultimately, cooking at the temperature–time combinations recommended by manufacturers and online recipes helped achieve complete microbial elimination in both appliances. This study contributes to the validation of home cooking methods to ensure consumer safety.     

PRESERVATION OF FISH SPREAD WITH ENTEROCINS 1071A AND 1071B, TWO ANTIMICROBIAL PEPTIDES PRODUCED BY ENTEROCOCCUS FAECALIS BFE 1071

Enterocins 1071A and 1071B, produced by Enterococcus faecalis BFE 1071, kept the total aerobic cell numbers in fish spread between 8 × 10⁴ and 2 × 10⁵ cfu/g for the first 6 days of storage. The total aerobic cell numbers in a batch preserved with a combination of sodium benzoate (0.045%, w/w) and potassium sorbate (0.059%, w/w) remained between 8 × 10⁴ and 2 × 10⁵ cfu/g during the first 18 days of storage. In a batch containing no preservatives, cell numbers gradually increased from 1 × 10⁵ to 1 × 10⁸ cfu/g over 21 days. The spoilage organisms were identified as Staphylococcus epidermidis and atypical Proteus vulgaris. The pH of all batches remained constant over the 21‐day storage period, with minimal variations recorded in textural and organoleptic qualities. The number of microbial cells recorded in fish spread preserved with enterocins 1071A and 1071B was 8 × 10⁶ after 21 days of cold storage (4C), whereas microbial cell numbers of 1 × 10⁸ were recorded in fish spread that had not been preserved.