Nowadays, there is a growing interest on how to utilize fish materials remaining from the main production and considered as unappropriated for a direct human consumption. There are numbers of possible solutions to recover valuable nutrients from that matter and one of the most efficient is the production of fish protein hydrolysate. This article is devoted to overview existing information about the production of dried fish protein hydrolysates with a focus on dehydration process during production and equipment used for moisture removal. Drying step of the production is considered as the most energy demanding and, therefore, described in detail. Questions considering energy demands of the drying are highlighted in the article together with the proposals for the improvement of energy efficiency. This work also describes source of the raw material, the main steps of the technological scheme with the equipment used and valuable information on the intermediate state of fish protein hydrolysate between the process operations. Keywords Drying Á Fish protein hydrolysate Á Fish by-products Á Industrial drying systems Abbreviations P Pressure (Pa) pH Logarithmic measure of hydrogen ion concentration (dimensionless) T Temperature (°C)
various types of dry-cured ham are due to pig breed, feed of pigs, their weight and age, as well as differences in the production process. High-quality dry-cured hams, with a production length longer than 1 year, have distinct organoleptic characteristics: a rich, unique, and recognizable flavor and color in the range from rosy to maroon or brown red marbled with white fat. However, the sensorial, physical-chemical, aromatic, morphological, and textural characteristics of dry-cured ham vary significantly depending on the alterations in the technological process from producer to producer [1][2][3][4][5].The traditional technology for the production of dry-cured ham mainly consists of salting, postsalting (resting), and drying-ripening stages. In Northern Europe (Germany, Scandinavia), smoking is frequently applied. Salting and drying-ripening are the most important steps in the manufacture where the flavor of the final product is mainly formed.The duration of the postsalting and the drying-ripening stages varies depending on the type of dry-cured ham. The drying-ripening step lasts from 2-3 months to 2-3 years for the highest quality dry-cured hams. Increased time of ripening gives a higher degree of enzymatic degradation, contributing to taste and flavor of the final product and as a consequence of higher quality of dry-cured ham [6]. Shorter processing time allows faster production of drycured ham, but the quality characteristics will suffer. The technology for each particular kind of dry-cured ham is adjusted according to the desired priority: quality or high production capacity.During ripening, endogenous enzymes degrade proteins and lipids to amino and fatty acids correspondingly, which are mainly responsible for the flavor of dry-cured ham [7]. Free amino and fatty acids are further degraded and converted by enzymatic and chemical reactions, including oxidation, to volatile compounds. Free amino acids contribute Abstract Dry-cured ham is a traditional meat product highly appreciated by consumers. Production of dry-cured ham is a time-consuming process which varies between different ham types. There are many factors affecting the final characteristics of dry-cured ham. The quality of the raw material and the process conditions mainly influence the rate and the extent of biochemical reactions which are in turn responsible for the formation of specific flavor and texture. This review paper highlights the characteristics of the raw material, the enzymatic and chemical processes taking place during dry-cured ham manufacture and the compounds formed by these reactions. The rates of the enzymatic changes from fresh meat to the stage of final product are also described.
Proteolytic activity and physico-chemical characteristics were studied for Norwegian dry-cured ham at four different times of processing: raw hams, post-salted hams (3 months of processing), hams selected in the middle of the production (12 months of processing) and hams at the end of the processing (24 months). Cathepsin H activity decreased until negligible values after 3 months of processing, whereas cathepsins B and B+L were inactive at 12 months. AAP was the most active aminopeptidase whereas RAP and MAP were active just during the first 12 months of processing. Proteolysis index reached a value of 4.56±1.03 % with non-significant differences between 12 and 24 months of ripening. Peptide identification by LC-MS/MS was done and two peptides (GVEEPPKGHKGNKK and QAISNNKDQGSY) showing a linear response with the time of processing were found. Unfreezable water content and glass transition temperature were investigated using differential scanning calorimetry (DSC) technique with non-significant differences in the temperature of glass transition for 12 and 24 months of processing.
is a technique which uses natural conditions-the sun and air-for product dehydration. Due to the great influence of weather conditions and not less due to safety reasons, nowadays a drying process takes place in ventilated climate chambers in which the product is held at constant temperature in a controlled atmosphere.The process of dry-cured ham manufacture is long and consists generally of salting followed by a long drying period. During the salting stage, the product is affected by the action of salt (NaCl) which penetrates and distributes uniformly during the resting step. Consequently, the part of moisture is removed from the product by the action of osmotic dehydration. It helps to prepare the product for the further drying step by reducing the energy costs by partial water removal.Drying is the main process of dry-cured ham production and consists of water removal from the product by evaporation which is driven by a concentration gradient between the drying air and the being dried product. Drying is the most energy-and time-consuming process and that is why optimization of this step is of special interest [1]. Latent heat of vaporization for water is 2257 kJ kg −1 water at temperature 100 °C and pressure in 1 atm [2]. It means that for the vaporization of one kilogram water, the energy input which should be applied to the product is 0.63 kWh kg −1 . It is an ideal case, and real energy costs can approach 3500-6000 kWh kg −1 . Thus, maintenance of the atmosphere at certain parameters requires sufficient energy expenses; therefore, it is crucial to achieve the maximally efficient drying process with a certain drying rate. At the same time, the quality of the product needs to be kept at a high level in order to be accepted by consumers. Along with environmental parameters, such product properties as salt content of being dried ham and pH value of the raw material are the Abstract Dehydration in foodstuff manufacture is a process when a product loses the weight by reduction in water content. Regarding the production of dry-cured ham, dehydration mainly takes place during the drying stage. However, during the salting and the resting steps, water content of the hams also reduces by 3-4 %, which should be taken into account in order to adjust the necessary rate of the further drying. In addition, such parameters as pH of the raw material and salt content of being dried hams also influence the drying rate and the quality of the final product. The present paper is devoted to highlighting processes and parameters influencing the dehydration of dry-cured ham during the manufacture. Industrial drying systems used for the manufacture of dry-cured ham are described for the comparison of construction and energy consumption. Mathematical models mostly used to predict the drying behavior of dry-cured ham are described.
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