Evolution of proteolytic and physico-chemical characteristics of Norwegian dry-cured ham during its processing

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.The work was supported by the Research Council of Norway (project 225262/E40 – DryMeat)Peer reviewe

Superchilling of food: A review

a b s t r a c t Food preservation is very important for the safety and the reliability of the product. Superchilling as used for preserving foods, has been defined as a process by which the temperature of a food product is lowered to 1-2°C below the initial freezing point. Fresh and high quality food products are in great demand worldwide. Temperature is a major factor determining the shelf life and quality of food products. Fish and meat are perishable food commodities, where better and more advanced preservation technology is needed. Deterioration of these foods mainly occurs as a result of chemical, enzymatic and bacteriological activities leading to loss of quality and subsequent spoilage. Storing food at superchilling temperature has three distinct advantages: maintaining food freshness, retaining high food quality and suppressing growth of harmful microbes. It can reduce the use of freezing/thawing for production and thereby increase yield, reduce energy, labour and transport costs. The study on the growth mechanism of ice crystals, modelling and computer simulation of foods during superchilling and superchilling storage is needed

Performance analysis of high temperature heat pumps and thermal energy storages for a dairy

This paper analyses the performance of the integrated energy system of an existing dairy in Bergen, Norway. The investigated dairy has an innovative solution for the thermal process supply by using only heat pumps and thermal energy storage to cover all temperature levels of the existing heating and cooling demand. The aim of the study was to determine the energy consumption and system performance for one winter week and one summer week and compare these results against each other. To evaluate the performance, a comprehensive energy analysis was carried out based on the available process data. The results show for a comparatively energy-intensive week in February that the integrated energy system covers the existing demand and can compensate for demand peaks, with a waste heat recovery rate of over 95% for the process. The chillers and heat pumps achieved high COPs in the range of 4.2 to 5.9, while the overall system achieved a total COP of 4.1. A comparative week in June was then investigated and compared with the results of the operating week in February. Due to higher building cooling demands and lower building heating demands, the demand for dry cooling was significantly increased in the summer, whereas the need for electric heating and district heating was reduced. The achieved COPs in the range of 4.2 to 5.7 were similar in the summer week, meaning that the energy system functions well in different climatic conditions. Based on the results of this study, the performance of the system under different conditions was evaluated and the impact on power consumption and potential use for other climatic regions was discussed.Performance analysis of high temperature heat pumps and thermal energy storages for a dairyacceptedVersio

Development of the natural working fluid‐based refrigeration system for domestic scale freeze‐dryer

In this work, the analysis of the refrigeration system designed for the FrostX 10 freeze‐dryer is presented. The main goal of this study was to experimentally investigate the reference R452a freeze‐dryer and prepare recommendations for a machine based on the R290 refrigeration unit. In order to guarantee the temperature requirements and efficient operation of that unit, the analysis of suitable natural refrigerants was performed. Consequently, propane (R290) was selected. In addition, a number of modifications were introduced for the prototype system. System analysis showed that the replacement of the refrigerant in the existing system improves the system energy efficiency by approximately 18%. During the experimental campaign of the basic refrigeration unit, an unstable operation of the evaporator was found. The concept of a new cooling system for a prototype device was presented. The configuration and type of heat exchanger to maximise the performance of the ice trap of the freeze‐dryer were proposed.Development of the natural working fluid‐based refrigeration system for domestic scale freeze‐dryeracceptedVersio

Low temperature drying and thermo-physical Properties of Brown seaweeds (Saccharina latissima)

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State diagrams in low temperature and atmospheric freeze drying of organic fruid products

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A steady and quasi-steady state analysis on the CO2 hybrid ground-coupled heat pumping system

This article contains the steady and quasi-steady state analysis on a CO2 hybrid ground-coupled heat pumping system for warm climates. The hybrid system uses a combination of ambient air and ground boreholes as a heat sink for the cooling mode, while only the ground boreholes are used as a heat source in the heating mode. The steady state analysis suggests that the optimal control strategy of gas cooler pressure for a CO2 hybrid transcritical cycle is based on the optimal cooling COP value and the ratio of heat rejected to ambient air. This optimal control strategy is important for decreasing the annual ground thermal imbalance performance of ground boreholes. In addition, the quasi-steady state model of a CO2 hybrid ground-coupled heat pumping system is constructed for the hourly simulation with different boundary conditions. Simulation results show the details of the system operating characteristics both for heating and cooling mode and the COP values with different operating and design conditions are presented.acceptedVersio

The influence of long-term storage, temperature and type of packaging materials on the quality characteristics of frozen farmed Atlantic Salmon (Salmo Salar)

The variations of biochemical, structural, sensory and microbiological characteristics of salmon were examined during the long-term frozen storage at –25 °C, –45 °C and –60 °C. The effects of four different types of packaging materials were studied as well. Lipid oxidation was measured by peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). After 1 year of storage at –25 °C, the concentration of PV in red and white fish muscles increased from 1.26 to 1.82, and from 1.08 to 1.76, respectively. Formation of TBARS was higher in the red muscles than in the white, and reached a value of 14.04 (mg malondialdehyde (MDA) kg-1 of fish) after 1 year of storage at –25 °C. Decreasing the temperature to –45 °C inhibited PV and TBARS formation, but the use of the best packaging materials gave equally good results at –25 °C. The concentrations of oxidation products were quite low for the storage conditions examined, which was reflected by the sensory analyses. The sensory analyses showed that salmon stored for 1 year at –25 °C maintained a level of quality comparable with fresh salmon. The colour alteration was affected by the storage time. The storage at –60 °C reduced drip loss (2.0% from total mass) when compared with those of the higher storage temperatures, but other quality improvements were not significant.submittedVersio

Production of fish protein hydrolysates step by step: technological aspects, equipment used, major energy costs and methods of their minimizing

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

Low Temperature Drying and Thermo-Physical Properties of Brown Seaweeds (Saccharina Latissima)

The drying kinetics of brown seaweed Sacharina Latissima with and without blanching were investigated in temperature range between 10.0 and 38.0 °C. The drying process is more rapid for raw seaweeds. The effective moisture diffusivity coefficient (with respect to shrinkage) was found in the range between 0.5 and 5.0 10-10 m-2/s. Drying temperature influence on lightness and hue color parameter of the seaweeds. The salt content in raw seaweeds influence on the shape of the sorption isotherm at high relative humidifies. The differential scanning calorimetry of raw seaweed samples revealed glass transition at ultra-low temperature range, while it was not found for blanched seaweeds. State diagram for drying and freezing of raw seaweeds was made