Psychrophilic Aerobic Bacteria Research Articles

Microbiological quality assessment of Clarias gariepinus, Bagrus bajad, and Pangasianodon hypophthalmus fillets

In this study, 80 catfish fillets were randomly collected from Egyptian local markets and retailers. The samples included 20 African catfish (Clarias gariepinus), 20 bayad (Bagrus bajad), and 40 pangasius catfish (Pangasianodon hypophthalmus) fillets. Pangasianodon hypophthalmus fillet samples were divided into 20 white basa and 20 red basa fillets. We conducted a microbiological analysis of catfish fillet samples, evaluating mesophilic aerobic bacteria, psychrophilic aerobic bacteria, H2S-producing bacteria, Staphylococcus spp., Enterobacteriaceae, Coliforms, and fecal Coliform counts. Additionally, we identified the existence of Salmonella spp., Vibrio spp., Yersinia spp., Escherichia spp., Aeromonas spp., and Pseudomonas spp. in the catfish fillet samples. In our study, the psychrophilic bacterial counts in Bagrus bajad (5.21 log CFU/g) were found to be higher compared to the counts in Clarias gariepinus (4.31 log CFU/g) and Pangasianodon hypophthalmus (3.89–4.7 log CFU/g). The fecal Coliform in Clarias gariepinus fillets was significantly higher than in other catfish fillets. We isolated Escherichia coli, Escherichia fergusonii, Aeromonas hydrophila, and Pseudomonas luteola from the catfish fillets, while no Salmonella spp., Vibrio spp., or Yersinia spp. were detected. These isolates were identified using 16S rRNA sequencing and phylogenetic analysis. Furthermore, ten Escherichia spp. were serologically identified, revealing that O26 and O78 were the most commonly occurring serotypes. This study highlights the microbiological analysis conducted on catfish fillets and concludes that the fillet samples from these catfish were of superior quality and deemed acceptable for human consumption.

Production techniques and product characteristics of “Kaymak” produced in Türkiye

With its unique creamy structure, delicious consistency, slightly acidic taste and aroma, “kaymak” is a traditional dairy product that is consumed with honey and jam for breakfast, in the production of Turkish delight with cream and cream candy, or in Turkish desserts such as kadayif and baklava because of its many features that increase the ornamentation, flavor and nutritional value. In Türkiye, two types of “kaymak” are produced as “Afyon Kaymağı” and “Lüle Kaymağı”, especially in the Aegean region (Afyonkarahisar and its surroundings) and Central Anatolia, as well as in Ankara, Bursa, Edirne, Erzurum, Istanbul, Izmir, Kilis and Kocaeli provinces. It is also produced from buffalo milk in countries such as the Balkans, Middle East, Central Asia, Iran, Afghanistan and India. It is described by names such as “kajmak”, “kaimak”, “gemagh” or “geymar”. The fact that the “kaymak” produced by the traditional method has a very open production process to microbial contamination, is a product that does not undergo fermentation, has a high water content and is rich in usable nutrients, increases the importance of the risk of contamination after the pasteurization process. It is evaluated that “kaymak” can provide an extremely favorable environment for the development of pathogenic microorganisms that Escherichia coli, E. coli O157:H7, coliform bacteria, Listeria spp., Listeria monocytogenes, Pseudomonas spp., Salmonella spp., Salmonella-Shigella, Staphylococcus, Staphylococcus aureus, total aerobic mesophyll bacteria, total aerobic psychrophilic bacteria, yeast and mould, which cause foodborne infections and food intoxications in humans and this situation may pose a risk for public health.

Düşük Basınç Uygulaması Taze ve Depolanmış Sudak Balığının (Sander lucioperca) Fizikokimyasal ve Mikrobiyolojik Özelliklerini Geliştirdi

IIn this study, low-pressure treatment was applied to pike-perch and the changes in quality criteria during the storage process were examined. L*, a*, and b* values in samples treated with low pressure were significantly different compared to the control. It was observed that the process had an improving effect on the textural properties of the fish. While the aw value decreased to 0.822, the pH value decreased to 6.47. While TBARS values of the samples ranged between 0.014 and 0.031 mg MA / kg, TVB-N values ranged between 7.69 and 24.06 mg / 100 g. Total aerobic mesophilic bacteria, yeast/mold, total coliform group bacteria, and total aerobic psychrophilic bacteria counts of all samples exposed to low-pressure treatment were lower than the control during storage. As a result, the treatment positively affected the quality of pikeperch meat during the storage period.

A New Ready-to-Eat Product Based on Enzymatically Peeled 'Hernandina' Clementine Segments and Citrus Syrup.

Ready-to-eat fresh fruit have an increasing presence in international markets due to their convenience and health benefits. However, these products are highly perishable and efficient technologies to increase their shelf life are needed. In the present research, different citrus fruit species and cultivars from organic farming were assessed to obtain enzymatically peeled citrus segments. The best results in terms of segment quality were observed for 'Hernandina' clementine, which was chosen to make a new ready-to-eat product based on peeled citrus segments that were packaged in glass jars with a light syrup made of citrus juice and organic sugar cane. Different citrus juice mixtures were assayed and the most appreciated syrup, based on the sensory scores given by panellists, was that containing 50-50 (v/v) of 'Fino' lemon and 'Hernandina' clementine juices. In addition, different pasteurization treatments were assessed for their effects on conserving the safety, nutritional quality and sensory properties of the product during cold storage. The results show that pasteurization treatment at 50 °C for 45 min was sufficient to prevent microbial contamination with mesophilic and psychrophilic aerobic bacteria or yeast and mould and to maintain sensory properties until five weeks of storage at 4 °C. In addition, only a 10% reduction in vitamin C concentrations was observed in fresh-segments or syrup until the end of the storage period, showing that a high bioactive compound content and health benefits were conserved in the new ready-to-eat product after pasteurization and prolonged cold storage.

Çaça (Sprattus sprattus, L., 1758) Protein Hidrolizatının Fizikokimyasal Özellikleri ve Alabalık (Oncorhynchus mykiss, Walbaum, 1792) Filetolarında Kaplama Malzemesi Olarak Kullanımı

Trout is the most widely cultivated and traded fish species in Turkey and many European countries, and a total of 471686 tons of production was realized in Turkey’s seas and inland waters in 2021. In addition to its nutritive value, this fish takes a crucial position in the aquaculture sector due to its continuous and intensive production. In this study, innovative bioactive protein hydrolysates (PH) produced from sprat were used as a coating to increase the quality and shelf life of trout fillets stored at +4 ˚C. The yields of traditional hydrolysate (TH) and ultrasound-assisted hydrolysate (UH) were 8.66% and 12.63%, respectively. Protein values of TH and UH were 75.88 and 74.45%, respectively. Three fillet groups were prepared from trout: uncoated control group (C), traditional enzymatic protein hydrolysate coated group (THC), and ultrasound-assisted enzymatic protein hydrolysate coated group (UHC). TVB-N value, which was 12.96 mg/100g in fresh trout, exceeded the consumable limit with 38.52 mg/100g on the 9th day of storage in the C. This value reached 32.92 mg/100g and 33.62 mg/100g on the 12th day for THC and UHC, respectively. At the beginning of storage, 0.21 mg MA/kg TBA reached the consumable limit with 7.72 mg MA/kg in the C on the 9th day, while THC and UHC remained within the limit with 6.67 mg MA/kg and 6.79 mg MA/kg, respectively. Total aerobic mesophilic bacteria (TAMB) and total aerobic psychrophilic bacteria (TAPB) counts on day 0 of storage were 2.13 log cfu/g and 1.66 log cfu/g, respectively. These values were calculated as 6.90, 5.20, 5.04, 6.95, 3.48, and 3.22 log cfu/g for C, THC, and UHC on the 12th day of storage, respectively. The application of ultrasound during the production of protein hydrolysate significantly increased the yield and hydrolysis degree of UH compared to TH. The lipid ratio of UH was also found to be significantly lower than TH. In these respects, the application of ultrasound has provided an advantage. Although both coatings have provided significant protection compared to the C, generally similar results were obtained between the THC and UHC. PH coatings delayed the chemical, physical, and microbial spoilage of trout fillets and extended the storage period. The results showed that PH can be used as a coating on fish fillets stored in cold conditions.

Antimicrobial activity of Spirulina platensis extract on total mesophilic and psychrophilic bacteria of fresh tilapia fillet

Spirulina platensis has a wide range of activities, notably antibacterial property against food pathogens. This study investigates the antibacterial activity of S. platensis extract on Total Mesophilic and Psychrophilic Aerobic Bacteria. The results were compared using statistical analysis and the predicted model values using artificial intelligence-based models such as artificial neural network (ANN) and adaptive neuro fuzzy inference system (ANFIS) Models. The extraction of spirulina was done by using the freeze–thaw method with a concentration of 0.5, 1 and 5% w/v. Before the application of the extract, initial microbial load of fillets was analyzed the and the results were used as control. After application analysis was performed at 1, 24 and 48 h of storage at 4 °C. Based on the statistical analysis result the S. platensis extracts’ antimicrobial activity over TMAB of fresh tilapia fish fillets at 1, 24 and 48 h was using EA from 2.5 log10 CFU/g during the control stage to 1.8, 1.1 and 0.7 log10 CFU/g respectively whereas EB and EC was from 2.1 and 2.2 log10 CFU/g at control to 1.5, 0.8, 0.5 log10 CFU/g and 1.23, 0.6 and 0.32 log10 CFU/g respectively at the specified hour interval. Similarly, the three extracts over TPAB were from 2.8 log10 CFU/g at control time to 2.1, 1.5 and 0.9 in EA, while using EB reduces from 2.8 log10 CFU/g to 1.9, 1.3 and 0.8 log10 CFU/g at 1, 24 and 48 h respectively. Although EC presented the reduction from 1.9 log10 CFU/g to 1.4, 1 and 0.5 log10 CFU/g. This was supported by ANN and ANFIS models prediction.

Microbial and Antibiotic Resistant E. coli Contamination in Retail Eggs Produced by Alternative and Conventional Rearing Methods

The aims of this study were to determine: i) the presence of total mesophilic aerobic bacteria (TMAB), total psychrophilic aerobic bacteria (TPAB) coliform, E. coli, Enterobacteriaceae and Salmonella in retail eggs produced in different poultry rearing systems, ii) Enterobacteriaceae species diversity, and iii) antibiotic resistance profile of E. coli isolates. A total of 350 retail eggs produced by four different rearing systems [organic (n= 100), free-range (n= 100), barn (n= 50) and conventional-cage (n=100)] were collected and characterized microbiologically. Out of the 350 eggs tested, the eggshell surface samples were contaminated, with TMAB, TPAB, coliform, E. coli and Enterobacteriaceae at positive percentages of 100%, 100%, 49.1%, 18.6% and 38%, respectively. The positive percentage of coliform, E. coli and Enterobacteriaceae were statistically significant between rearing systems (P<0.05). However, only mean numbers of TMAB were statistically significant between rearing systems (P<0.05). The contamination percent positive crushed eggshell samples, with TMAB, TPAB, coliform, E. coli and Enterobacteriaceae were 100%, 100%, 50%, 33.7% and 42.5%, respectively. Salmonella was detected from only one Enterobacteriaceae isolate obtained from an organic eggshell pool but not from eggshell surfaces or egg yolks. A total of 35 E. coli isolates were recovered from Enterobacteriaceae isolates. Twelve (34.3%) of them exhibited resistance to least one antibiotic tested. The dominant type of resistance was to ampicillin detected in all 12 E. coli isolates. This study provides valuable baseline data of the occurrence of species diversity of Enterobacteriaceae and antibiotic resistant E. coli in retail eggs produced by alternative or conventional-caged rearing methods which can be used for future risk assessments.

Electrospun eugenol-loaded gelatin nanofibers as bioactive packaging materials to preserve quality characteristics of beef

In this study, electrospinning technique was employed to fabricate eugenol loaded gelatin nanofibers (ELGNs) by using gelatin as an active material to encapsulate eugenol. The results indicated that eugenol could be successfully encapsulated within nanofibers, as verified by SEM, FTIR, and zeta potential analyses. The average zeta potential value of ELGNs was determined to be − 15.08 mV. The average diameter of gelatin nanofibers was enlarged with eugenol encapsulation, increasing to diameter of 125 nm. ELGNs had a smooth and uniform fiber morphology observed by SEM. The ELGNs demonstrated a potent antibacterial activity by significant (P < 0.05) reduction in the number of total mesophilic aerobic bacteria counts by 1.62 log and psychrophilic aerobic bacteria counts by 1.33 log in fresh beef samples treated with ELGNs. Moreover, the bioactive ELGNs maintained textural properties (hardness–4.75 N, gumminess–1.75 N, and chewiness–3.87 N × mm at 9th day of storage) and sensory properties, exhibiting advantages as antimicrobial packaging materials that maintained the quality and freshness of the raw meat, along with the extension of its shelf life to 9 days. Significant (P < 0.05; 0.01) negative and positive correlations were found among the microbiological, textural, and sensory parameters, which explained and confirmed the reason for the effectiveness of the nanofiber treatment. In conclusion, our results suggested that the electrospinning approach in this study could be an effective technique to encapsulate eugenol within gelatin nanofibers and the electrospun ELGN mats could be a novel bio-degradable active packaging material with good antibacterial effects.

The Effect of Some Natural Antioxidants on Quality Properties of Pikeperch (Sander lucioperca) Meat Balls

Bu çalışmada bazı doğal antioksidanların sudak balığı (Sander lucioperca) köftelerinin kalitesine etkileri araştırılmıştır. Bu amaçla balık kıymasına portakal ve limon özütü hem birlikte hem de ayrı ayrı ilave edilerek çeşitli baharat ve katkı maddeleri ile balık köfteleri elde edilmiştir. Çalışmada portakal özütü ilaveli grup (P), limon özütü ilaveli grup (L), portakal ve limonun birlikte ilave edildiği grup (PL) ve hiçbir meyve özütünün ilave edilmediği klasik balık köftesi grubu (K) olmak üzere 4 farklı grup oluşturulmuştur. Balık köfteleri raf ömrü tespiti amacıyla duyusal ve mikrobiyolojik analizleri yapılmış ve 4±1oC’de muhafaza edilmiştir. Mikrobiyolojik analizlerde Toplam Mesofilik Aerobik Bakteri (TMAB), Toplam Psikrofilik Aerobik Bakteri (TPAB) ve Laktik Asit Bakteri (LAB) sayıları depolama süresince gruplara göre farklı değerler sergilemiştir. Çalışma sonuçlarına göre, kullanılan bitki özütleri sudak köftelerini daha iyi korumuştur. Kontrol grubu 15 günde tüketilemeyecek duruma gelirken L ve PL grupları 19. günde, P grubu 21. günde raf ömrünü tamamlamıştır. Duyusal olarak en çok beğenilen grup P grubu olmuştur. En uzun ömürlü ürün de yine P grubu sudak köfteleri olmuştur.

Determination of microbiological quality and histamine levels in rainbow trouts (Oncorhynchus mykiss)

This study aims to determine the microbiological quality and histamine levels of fresh-marketed rainbow trouts (Oncorhynchus mykiss). The total mesophilic aerobic bacteria (TMAB), total psychrophilic aerobic bacteria (TPAB), coliform, fecal coliform, Enterobacteriaceae, Pseudomonas, Staphylococcus-Micrococcus and mold-yeast numbers were detected as 4.24, 4.00, 1.10, 0.17, 1.50, 3.05, 0.28 and 3.82 log10 cfu/g, respectively. Yersinia enterocolitica, Listeria monocytogenes, Escherichia coli O157:H7 and Vibrio spp bacteria were found in 18 (37.5%), 14 (29.1%), 8 (16.6%) and 14 (29.1%) respectively. Twenty-eight out of 51 Listeria isolates (54.9%) were verified through PCR analysis as L. monocytogenes. It was determined that the histamine level in the samples was above the detectable level (&gt;2.5 mg/kg) in 8 of the samples (16.6%)determined using an ELISA method. It was concluded that the detection of foodborne pathogens in fresh-marketed fish samples potentially constitutes a public health hazard.

The impacts of ultrasound-assisted protein hydrolysate coating on the quality parameters and shelf life of smoked bonito fillets stored at 4±1ºC

Innovative bioactive protein hydrolysates (PH), produced from Rainbow trout (Oncorhynchus mykiss W., 1792) by-products, were used as a coating on smoked fillets of bonito (Sarda sarda) for extension of the quality and shelf life during chilled storage for 60 days. Three fillet groups were prepared as control group without coating (CG), normal hydrolysate coated group (NHCG), and ultrasound-assisted hydrolysate coated group (UHCG). Total volatile basic nitrogen (TVB-N) and TBA values exceeded the acceptable limits on the 39th and 33rd days for CG respectively; 60th day for NHCG and UHCG. However TBA of UHCG was significantly lower than NHCG. Total aerobic mesophilic bacteria (TAMB) and total aerobic psychrophilic bacteria (TAPB) loads reached 6.32±0.06 and 7.30±0.12 log cfu/g for CG on the 39th day. TAMB and TAPB values of NHCG and UHCG have remained within the limits of consumable until the end of the storage. PH coatings prolonged the storage of fillets by delaying chemical, physical, and microbial degradation. Results showed that ultrasound-assisted PH could be used as a coating for smoked bonito at refrigerated conditions, delaying oxidation and microbial degradation.

Determination of the Risky Microorganisms in Frozen Ready-to-Eat Seafood Sold in Istanbul Market

Since frozen ready-to-eat seafood has the potential to cause food poisoning, this study focuses on microorganisms that have the potential to be a health hazard found in frozen ready-to-eat seafood, which is sold to highly populous communities. Therefore, the most popular frozen ready-to-eat seafood, fish balls and surimi crab legs, from Istanbul market were studied. Samples were gathered from seven different branches of four major chain market brands, twice in winter (October-March) and twice in summer (April-September). As a result of seasonal conditions summer samples had higher microbial loads compared to winter samples. The average mesophilic and psychrophilic aerobic bacteria counts of fish balls and surimi crab legs were below ≤4 log cfu/g. All samples were safe in terms of Salmonella, Vibrio parahaemolyticus and Vibrio cholerae; and acceptable in terms of Staphylococcus aureus Clostridium perfringens, and Bacillus cereus. The microbiological load of fish balls was higher (p&lt;0.05) than the other samples. It was observed that more than 80% of them are risky in terms of coliform bacteria. It is concluded that attention should be paid especially to minced and spice added products. It is essential to pay more attention to the marketing of ready-to-eat seafood during the summer seasons for the prevention of public health.

Effects of Plant Extracts on the Quality of Sous Vide Meagre (Argyrosomus regius) Fillets

This study aimed to determine the changes in the quality of sous vide meagre (Argyrosomus regius) fillets that have been treated with oregano and rosemary extracts during the cold storage (4±1 °C). Saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids dominant in meagre fish were found to be palmitic acid, oleic acid, and linoleic acid, respectively. pH values fluctuated during storage in sous vide samples. It was determined that total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA) and trimethylamine nitrogen (TMA-N) values did not exceed the limit values during the storage period in the Control SV, Rosemary SV, and Oregano SV groups. The total number of mesophilic aerobic bacteria (TMAB) and total psychrophilic aerobic bacteria (TPAB) on the 42nd day did not exceed the limit values in the Control SV, Rosemary SV, and Oregano SV groups. During the cold storage, lactic acid bacteria, yeast, and mold were not detected in sous-vide cooked groups. It has been determined that rosemary and oregano extracts improve the sensory quality of the product in taste and smell.

Nutritional, physical, microbiological, and sensory properties of marinated Irish sprat

Atlantic Sprat (Sprattus sprattus) is a highly nutritious pelagic fish of great commercial value in Eastern Europe and Scandinavia which in Ireland is largely under-utilised for human consumption.The aims of this study were to develop a marinated product from Irish sprat, to evaluate its physico-chemical characteristics; and to compare sensory qualities of the Irish sprat product (ISP) with established European analogues.Physico-chemical analysis of the marinated product included proximate analysis, pH, sodium chloride, colour, and texture, while microbiological tests were conducted for total viable bacterial count (TVBC), total psychrophilic aerobic bacteria (TPBC), total yeast and mould, and total coliform counts (TCC). Sensory attributes of the Irish sprat product were assessed by panel tasting using hedonic and just-about-right (JAR) scales and compared to Nordic (NSP) and Mediterranean marinated (MAN) products.This study demonstrates that the curing methods used significantly increased ash content and reduced water content of fresh sprat (P < 0.05) thus contributing to product preservation. Specifically, preservation was achieved by reducing the marinated product's pH value and water activity and increasing the salt content thereby inhibiting all microbial growth across all curing stages.Hedonic and JAR data showed positive acceptance from consumers for most ISP sensory characteristics. However, JAR scores were lowered by panellist's perception of excessive acidity and fishiness indicating that broad consumer acceptance of an ISP product will depend on the freshness of the raw material available to processors.

Tokat ve Çevresinde Çiğ Olarak Satışa Sunulan Parça Kırmızı Etlerin Mikrobiyolojik Kalitesi

Dünya Sağlık Örgütü (DSÖ)‘nün tahminlerine göre her yıl 600 milyon insan kontamine gıdaların tüketimi sonucu hastalanmakta ve 420.000 kişi ölmektedir. Birçok gıda, gıda kaynaklı hastalıkların kaynağı olabilmekle birlikte et son yıllarda ön sıralarda yer almaktadır. Et, insan sağlığı üzerinde önemli olan bazı gıda kaynaklı patojenlerin kaynağıdır. Bu çalışmada; Tokat ilinde satılan çiğ sığır eti örneklerinin mikrobiyolojik kalitesinin incelenmesi ve sonuçlarının gıda güvenirliği bağlamında değerlendirilmesi amaçlanmıştır. Bu nedenle, kasaplardan ve marketlerden satın alınan 18 çiğ et örneği toplam mezofilik aerobik bakteri, toplam psikrofil aerobik bakteri, maya-küf, laktik asit bakteri, Bacillus cereus, Staphylococcus aureus, Clostridium perfringens, toplam koliform ve fekal koliform için analiz edilmiştir. Ayrıca; Escherichia coli, E. coli O157:H7, Listeria monocytogenes ve Salmonella spp. varlığı da araştırılmıştır. Örneklerin; en düşük ve en yüksek değerleri toplam mezofilik aerobik bakteri, toplam psikrofil aerobik bakteri, maya-küf, laktik asit bakteri, B. cereus, S. aureus, C. perfringens, toplam koliform ve fekal koliform sırasıyla 1,46×104-1,26×107 kob/g, 1,01×104-2,65×106 kob/g, 3,00×103-1,70×104 kob/g, 2,70×103-3,60×104 kob/g, Ë‚102-7,20×104 kob/g, 2,60×103-2,57×105 kob/g, Ë‚102-9,20×103 kob/g, 3,80×101-2,90×104 EMS/g ve

Development of Shelf Life Prediction Model in Rainbow Trout Stored at Different Temperatures

ABSTRACT The aim of this study was to develop a shelf life prediction model for aerobically stored gutted and whole rainbow trout. Logistic model was used to determine the specific growth rates of total mesophilic aerobic bacteria, total psychrophilic aerobic bacteria, Pseudomonas spp., Enterobacteriaceae, and lactic acid bacteria (LAB) for the samples stored at different temperatures (2°C, 5°C, 10°C, 15°C, 20°C, and 25°C). To describe the effect of temperature on the growth of bacteria, the square root model was used. The validation of the developed shelf life prediction model was carried out using whole (ungutted) rainbow trout at constant temperatures. The bias and accuracy factors of predicted values were within the range of 0.80–1.20, where the model could be valid. The shelf life of whole and gutted aerobically stored rainbow trout can be predicted by the model accurately at any temperature between 2-25°C.

Effects of chitosan edible film coatings on the physicochemical and microbiological qualities of sweet cherry (Prunus avium L.)

In this study, the effects of chitosan edible film coatings on the physicochemical and microbiological qualities of sweet cherry (Prunus avium L.) were investigated. Sweet cherries were coated with 1% chitosan [two of which were produced from shrimp waste originating from the Marmara Sea in Turkey (Chitosan-1, Chitosan-2) and the other two of which were commercially produced (Commercial-1 and Commercial-2)] and stored at 4 °C for 25 days or 20 °C for 15 days. Various physicochemical (weight loss, pH, titratable acidity, total soluble solids, water activity, respiration rate, total carbohydrate content) and microbiological (total mesophilic aerobic bacteria, total psychrophilic aerobic bacteria, total coliform bacteria, yeasts and molds) qualities were measured. After storage, the least weight loss was found to be 8.85% in Chitosan-2 coated sweet cherries at 20 °C and 16.18% in the control group stored at 4 °C. The lowest titratable acidity value was observed in the control group (0.657%) at 4 °C and in the Chitosan-2 coated sweet cherries (0.600%) at 20℃. The water activity value was determined at 0.969-0.974 for all sample groups and storage conditions at the end of each period. The total count of mesophilic aerobic bacteria in the sweet cherry coated with CH-1 and CH-2 was found to be below the detectable amount (<2 logCFU/g) while that for the control group was 2.74 log CFU/g at 4 °C. Coating sweet cherries with CH-1 and CH-2 inhibited yeast and mold growth at 4 °C for 25 days while the highest yeast and mold count was determined as 4.75 log CFU/g in C-2 coated sweet cherries at the end of storage. It has been determined that each tested chitosan coatings have different effects on various quality characteristics at distinct storage temperatures. When microbiological analyses are taken into consideration, it can be concluded that chitosan, especially those produced from shrimp wastes, have high antimicrobial effects and can be used effectively in increasing the shelf life of sweet cherries.

Fabrication of olive leaf extract and hazelnut skin incorporated films to improve the quality of nuggets during refrigerated and deep freeze storage

ABSTRACT 1. Olive leaf extract (OLE) and hazelnut skin (HS), which are known to have good antioxidant activity, were added into chicken nuggets in different ways. In the first method, the nuggets were coated with sodium alginate-calcium chloride-based coatings containing OLE and HS. In the second method, OLE and HS were directly added into the nugget patties. Nuggets that did not contain any additive (C1) and the samples prepared with the coating solution that did not include any additives (C2) were assigned as controls. 2. Nuggets were stored at two different temperatures, either in a refrigerator (4°C) or in a deep freezer (−18°C) for 21 days and 90 days respectively. Moisture content (%), pH, antioxidant status (TBARS), colour and microbial count (total mesophilic and psychrophilic aerobic bacteria) analyses were carried out during storage. 3. At the end of refrigerator storage (day 21), TBARS values for samples in which OLE and HS were directly added were found to be lower than those with OLE and HS coatings (P < 0.05). Total number of mesophilic and psychrophilic bacteria were found to be the lowest in the treatment in which HS was directly incorporated into nugget patty (P < 0.05). 4. For frozen samples, application of a coating containing OLE and HS and direct addition of HS into patties were found to be effective in reducing lipid oxidation. No microbial growth was determined in most of the samples stored in the deep freezer.

Effects of the supplementation of lamb rations with oregano essential oil on the antimicrobial and antioxidant metabolism in meat

Although oregano essential oil has common use in the cosmetics, pharmaceutical, and food sectors, information on its effects on meat quality and shelf life, when incorporated into lamb feed rations, is scarce. In this study, the effects of oregano essential oil (OEO) in feed on the water activity, pH, lipid peroxidation, color parameters, and microbial counts of the Musculus longissimus dorsi (MLD) were investigated. The control group was fed a basal ration and the OEO1 and OEO2 groups were fed a basal ration supplemented with 200 mg/kg and 400 mg/kg OEO, respectively. Akkaraman lambs were fed experimental rations for a period of 56 days and were slaughtered at the end of the fattening period. Lipid peroxidation of the MLD was significantly affected by storage time (ST), group (G) and ST × G, while pH was affected by ST. Lightness was significantly affected by ST, G, and ST × G; redness by ST and G; and yellowness by ST and ST × G. The Micrococcus/Staphylococcus, total mesophilic aerobic bacteria, and total psychrophilic aerobic bacteria counts were significantly affected by ST, G, and ST × G; Pseudomonas spp. counts by ST; and coliform counts by ST and ST × G. The antioxidant and antimicrobial effects of OEO were confirmed.

Effect of brine and dry salting methods on the physicochemical and microbial quality of chub (Squalius cephalus Linnaeus, 1758)

Abstract The present study, looks at the physicochemical and microbiological quality changes that occur due to different salting techniques (20% salt concentration) of chub (Squalius cephalus) and when stored in 4 ± 0.5 °C. Samples of fish from each group was taken on the 15, 30, 45, 60, 90 and 120th day and was analyzed for nutritional component (crude protein, lipid, moisture, crude ash), pH value, salt content and the microbial flora (total mesophilic aerobic bacteria count, total coliform, total psychrophilic aerobic bacteria count, yeast and mould). It was determined that crude protein, lipid, crude ash and salt amounts in the group where dry salting method was applied were higher than the group where brine salting occurred, in addition protein and lipid values decreased as storage period was longer (P < 0.05). It was determined that there is an increase in total aerobic mesophilic, psycrophile bacteria and enumeration of yeast and mould as storage period increased, while coliform bacteria decreased (P < 0.05).