LIQUID–SOLID EXTRACTION OF SOLUBLE SOLIDS AND TOTAL PHENOLIC COMPOUNDS OF CAROB BEAN (Ceratonia siliqua L.)

Total mass transfer coefficients of soluble solids (SS) and total phenolic compounds (TPC) were determined during carob extraction. The Arrhenius equation was applied to determine the efficiency of process temperature, as an alternative approach to Fick's second law. Carob pod, cut into small pieces (internal diameter: 5–7 mm), was contacted with water in batch system to extract SS by continuous circulation of water at different temperatures (20, 50 and 85C). The process was also performed at 85C using an industrial‐scale extractor. Activation energies for both SS and TPC diffusions were calculated as 5.84 and 0.072 × 10^?3 kJ/mol, respectively. As expected, higher extract concentrations were achieved with higher temperatures. In contrast, high extraction temperature, even at 85C, did not cause hydroxymethylfurfural (HMF) formation. As the increase in temperature does not affect formation of HMF during carob pod extraction, higher operational temperatures such as 80–90C may be applied to obtain higher solute concentrations.     

KINETIC MODELING OF ANAEROBIC THERMAL DEGRADATION OF ASCORBIC ACID IN ROSE HIP (ROSA CANINA L) PULP

Ascorbic acid loss in thermally treated rose hip pulp was modeled mathematically. Isothermal experiments in the temperature range of 70–95C were utilized to determine the kinetics of ascorbic acid loss in the pulp during heating under anaerobic circumstances. Changes in ascorbic acid decomposition followed a first‐order reaction. Temperature dependence of the rate constant during thermal processing of rose hip pulp obeyed the Arrhenius relationship with an activation energy of 47.5 kJ/mole.     

SEASONAL CHANGES IN PROXIMATE COMPOSITION OF ANCHOVY AND STORAGE STABILITY OF ANCHOVY OIL

Changes in proximate composition of anchovy were investigated during the catching season from October to March. In addition, stability of anchovy oil depending on storage temperature and time were studied. During the recent study, water, fat, protein and ash content of anchovy varied between 65.9–74.0%, 9.0–15.3%, 12.8–16.4% and 1.7–2.2%, respectively. The anchovy oil stored at 4C was found to be unacceptable for consumption at the end of the 90th day of storage according to peroxide, acid, unsaponifiable matter and thiobarbituric acid values. An identical sample stored at − 18C was acceptable for 120 days of storage, but eventually became unacceptable after that.

PRACTICAL APLICATIONS

Anchovy has a great economic importance for the Turkish fishery industry. Approximately 42% of the annual catch of anchovy is used in fish meal and oil production in Turkey ( SIS 2002 ). Therefore, the proximate composition of anchovy and seasonal changes have fundamental importance for consumers, manufacturers and wholesalers, because it is important for consumers to know what they eat, for manufacturers to figure out how they manage long storage stability for their products, and for wholesalers to buy equivalent of their payment. An important issue that has attracted attention of the manufacturers is the storage life of fish oil. Therefore, the results presented in this study are expected to be useful for the fish oil industry in Turkey or even in other countries processing anchovy into fish oil.     

EFFECT OF ACID ADAPTATION AND DIFFERENT SALT CONCENTRATIONS ON SURVIVAL OF LISTERIA MONOCYTOGENES IN TURKISH WHITE CHEESE

ABSTRACT

Survival of acid‐adapted and nonacid adapted Listeria monocytogenes in Turkish white cheese with different salt concentrations (3.8 and 6.7% NaCl) was investigated. Cheese blocks were inoculated with L. monocytogenes and stored at 4C for 15 days. Samples were taken on different days and analyzed for the numbers of the pathogen, and the samples were challenged with simulated gastric fluid (SGF) for determining acid tolerance. There was no significant differences between the numbers of acid‐adapted and nonadapted L. monocytogenes cells regardless of the salt concentration on sampling days (P > 0.05). Challenge in SGF revealed that there was no significant difference between acid‐adapted and nonadapted bacteria in cheese with 3.8% NaCl throughout the storage period, while significant (P < 0.05) differences between those cells in cheese with 6.7% NaCl were found after day 5. These results suggest that acid‐adapted L. monocytogenes exposed to high salt concentration such as 6.7% may have an advantage in SGF.

PRACTICAL APPLICATIONS

Evaluation of potential stress responses of pathogens in food is important to understand the behavior of pathogens that can survive under stresses. As an environmental contaminant, Listeria monocytogenes may acquire adaptation to low acid conditions in cheese plants. Our results suggested that although there was no significant difference between acid‐adapted and nonadapted cells both in industrial (3.8% salt) and traditional (6.7% salt) white cheese, salt concentration significantly affected the survival of acid‐adapted cells in simulated gastric fluid (pH 2.3). These findings may indicate that L. monocytogenes, which is adapted to acid before contaminating high salt cheeses, may survive in stomach and cause infection. It can be said that increased salt concentration in cheese may not provide a barrier against acid‐adapted L. monocytogenes.

     

The effect of heat treatment and starter culture on colour intensity and sensory properties of Kulek cheese

The effect of the heat treatment on colour intensity and sensory properties of Kulek cheese made from raw milk with (RS) or without starter culture (R) and heated milk with starter culture (HS) was investigated during ripening. Colour L, a and b values of Kulek cheeses were determined for both interior and surface. The values for cheese R were 82.4 and 74.5 for L, ?5.2 and ?5.5 for a, 31.0 and 34.7 for b interior and surface respectively. The equivalents for RS cheese were 82.8 and 75.7 for L, ?4.8 and ?5.0 for a, 31.0 and 34.0 for b. The values for HS cheese were 88.9 and 88.4 for L and ?3.3 and ?3.3 for a, 22.8 and 24.2 for b. L values (lightness) were the highest in cheeses made from heated milk while b and negative a values were the highest in cheeses made from raw milk. Aroma scores of raw and heat‐treated milk cheeses made with starter were not significantly different. The panelists scored cheeses made from raw milk without starter as the best in body and texture.     

MICROBIOLOGICAL, PHYSICO-CHEMICAL AND TOXICOLOGICAL QUALITY OF TRADITIONAL TURKISH CHEESE DESSERTS

ABSTRACT

A total of 100 fresh‐cheese‐based desserts (Hosmerim and Cheese helva) from nine different production areas in Marmara Region of Turkey were studied. There were no statistically significant differences in microbiological composition between Hosmerim and Cheese helva. Mean values of APC, Staphylococcus aureus, molds, yeasts, osmophilic yeasts for Hosmerim were 5.7 × 10⁴, 8.0 × 10², 1.8 × 10³, 2.8 × 10³, 1.6 × 10³ cfu/g, respectively, while coliform bacteria, Escherichia coli and Bacillus cereus were <10 cfu/g. Results for Cheese helva were slightly higher. Salmonella spp. and staphylococcal enterotoxin were not detected in 25 g of any sample. Cheese helva, however, had a significantly lower pH and significantly higher contents of protein, fat and carbohydrates, and thus, also a higher content of dry matter. Within each product category, a large variation was observed for both microbiological counts as well as for the chemical composition. This indicates a lack of standardization in the manufacturing process and prompts for the establishment of appropriate process control measures.

PRACTICAL APPLICATIONS

The aim of this study was to determine the chemical and hygienic quality traits of traditional cheese desserts, namely Cheese helva and Hosmerim. For this purpose, 50 Cheese helva and 50 Hosmerim samples obtained from different regions in Turkey were analyzed on account of their microbiological, physico‐chemical and toxicological properties. The presence of some pathogens in the samples and the variable chemical composition indicate that the production process should be defined in “Codes of Good Manufacturing Practice” and the product characteristics should be codified in order to achieve a product with a defined level of microbiological safety.