Sodium reduction in muscle foods: Analytical methods for measuring sodium and changes in the food matrix during sodium reduction in muscle foods.

Salt (NaCl) is the world’s most established food additive, because of its excellent preservative effects, its positive effect on technological and sensory properties, and low cost. This combination of factors has resulted in salt being used at higher levels than necessary in many food products, particularly processed foods. However, a high consumption of sodium is also associated with an increased risk of high blood pressure, which has been found to be a significant contributor to the development of cardiovascular diseases and strokes in humans. In addition, a high salt intake has been linked to increased risk of stomach cancer, renal stones, and decreased bone mineral density. For these reasons, the WHO recommends a decrease in sodium consumption, to a total of 5 g NaCl per person per day (2 g Na per day). To reach the WHO target, the food industry therefore has to reduce the sodium content in their products by 30 -50%. A reduction of this magnitude could lead to challenges with regards to processing, physicochemical properties, yield, sensory attributes, texture, and food safety of the products. Partial replacement of the sodium salt by salt replacers and other ingredients will therefore be necessary. Given this, the main objectives of the present thesis are 1) to evaluate different analytical methods for measuring sodium in a food matrix, and to evaluate changes in this food matrix as a function of sodium reduction; and 2) to increase the theoretical understanding of the effect of salt and salt replacers on food sensory and physicochemical properties. The first objective is of importance given the high focus on the necessity of salt reduction in food products, and the increased use of salt replacers such as potassium chloride (KCl) in its stead. This makes it necessary to find new rapid techniques for determining the sodium content in products. For the purposes of this study, the following four methods were evaluated: (1) Impedance spectroscopy, (2) LF-NMR T2 relaxation method (LF-NMR), (3) Computer Vision, and (4) sodium ion-selective electrode. The methods were applied to food matrixes containing different amounts of salt (NaCl), and the salt replacers KCl and magnesium chloride (MgCl2). The model products consisted of minced fish prepared from hake (Merluccius paradoxus/capensis) and haddock (Melanogrammus aeglefinus). These products had different amounts of pure salts and mixtures of salts added beforehand, and were analyzed using the different methods above. Knowledge transfer from research in lab-scale to industry requirements for commercialization has been of utmost importance in i the work with this thesis. Cooked ham of pork and fish pudding were therefore prepared with a more complex composition of ingredients in order to investigate the effect of salt reduction on physicochemical and sensory properties of the final products as well. The work in this thesis has demonstrated that the method (1) impedance spectroscopy could be a potential technique for monitoring aw in low-salt low–fat fish mince, in that it is able to indirectly predict the amounts of salt in the sample. The (2) LF-NMR measurements on both raw and cooked fish mince added low levels of salt (0-3%), showed that this method was sensitive to the resultant changes in protein structure of the products due to the salt addition. The results of this thesis furthermore confirmed that the (3) multimodal machine vision system (Computer Vision) showed changes in lightness as a function of reduced salt content in cooked ham, and that the (4) sodium ion selective electrode is another good method for direct measurement of sodium in low-salt low-fat food products. The extractability of salt soluble proteins (SSP), were found to increase with higher concentration of salt in the products. The results indicated that Na+ can partially be replaced with K+ and Mg2+ without changing the solubility of proteins. However the addition of Mg2+ should only be used in small amounts, due to the negative effect on protein solubility at 0.55 M MgCl2. Freezing and thawing of haddock fillets furthermore decreased the solubility of SSP and influenced the physicochemical properties in cooked fish minces, adding other types of cations than Na+ did not compensate for these changes. This work also confirmed that the solubility of proteins affect the quality in the final product. This was demonstrated by both the Water-holding capacity (WHC) and breaking force increasing with higher levels of SSP in the study on fish pudding, for instance. A linear relation between breaking force and WHC was also found. In the model product made of haddock mince, with added water and different amount of pure salts, salt reduction led to an increase in moisture, reduced WHC, increased cooking loss and a decrease in breaking force. The pH also increased with decreasing salt content. Replacing NaCl with pure KCl had no, or only a small, effect on the pH, moisture, breaking force, WHC and cooking loss in the model products. Replacing NaCl with an equal molar concentration of MgCl2, however, affected several of the physicochemical properties and in particular WHC, cooking loss and pH. In light of this, and in summation, a partial replacement of Na+- ions with K+ - ions is possible without changing the protein solubility and the physiochemical properties in fish products. A reduction of salt from 1.0 down to 0.6%, without any salt replacers, affected the taste experience more than the physicochemical properties in fish pudding. Based on the investigated factors in this study a 40% sodium reduction is possible in fish pudding using high mineral permeate as a salt replacer. The study on cooked ham, however, showed that only a 25% replacement of Na+ - ions with K+- ions was possible without changing the quality in the final product. However, when the sodium was reduced by more than 35% (< 2.1% salt in the product), the salt reduction influenced both the sensory and physicochemical properties negatively

The effect of freeze-chilling on quality changes of cod loins (Gadus morhua) during chilled storage

Fish is highly perishable and has a short shelf-life. Freeze-chilling involves freezing and frozen storage followed by thawing and chilled storage. It offers more sustainable logistic benefits as it enables the products to be held frozen and released into the chill chain as required. Freeze-chilling can offer consumers high quality fish products throughout the year. The study was performed in the industry and included industrial methods for thawing, filleting, packaging, and freezing. The effect of freeze-chilling and chilling on vacuum packed cod loins was evaluated by sensory evaluation, drip loss, and total viable counts (TVC). Loins were stored at 4°C for up to 14 days after thawing. Analyses were performed on day 0, 6, 10 and 14. The results indicated that cod loins worked well as freeze-chilled vacuum-packed loins during short-term chilled storage after thawing. Freeze-chilled samples kept acceptable quality based on the sensory score but had higher drip loss.acceptedVersio

Freeze-chilling of whitefish: Effects of capture, on-board processing, freezing, frozen storage, thawing, and subsequent chilled storage—a review

The current review investigates how whitefish quality is affected by capture at sea, on board handling, freezing, double freezing, frozen storage, thawing, and chilled storage. Packaging of fillets in MAP and vacuum are also covered. The main goal was to evaluate the freeze-chilling concept as a possible method for the fishing industry for all-year-round marketing of fish captured during the relatively short fishing period. The review covers both the effect of each processing step in the supply chain as well as the combined effect of all steps in the chain from sea to consumer, including post-thawing chilled storage, defined as the freeze-chilling method.publishedVersio

Utilization of egg-laying hens (Gallus Gallus domesticus) for production of ingredients for human consumption and animal feed

In Norway, 3 million discarded egg-laying hens are destructed annually, which equals 1500 tons pure hen meat. Due to the slaughter methods used, this raw material is handled as a high-risk waste, while in reality it constitutes a source of valuable components like proteins and lipids.publishedVersio

Freeze-chilling of whitefish: Effects of capture, on-board processing, freezing, frozen storage, thawing, and subsequent chilled storage—a review

The current review investigates how whitefish quality is affected by capture at sea, on board handling, freezing, double freezing, frozen storage, thawing, and chilled storage. Packaging of fillets in MAP and vacuum are also covered. The main goal was to evaluate the freeze-chilling concept as a possible method for the fishing industry for all-year-round marketing of fish captured during the relatively short fishing period. The review covers both the effect of each processing step in the supply chain as well as the combined effect of all steps in the chain from sea to consumer, including post-thawing chilled storage, defined as the freeze-chilling method

Gradual Reduction in Sodium Content in Cooked Ham, with Corresponding Change in Sensorial Properties Measured by Sensory Evaluation and a Multimodal Machine Vision System

The European diet today generally contains too much sodium (Na+). A partial substitution of NaCl by KCl has shown to be a promising method for reducing sodium content. The aim of this work was to investigate the sensorial changes of cooked ham with reduced sodium content. Traditional sensorial evaluation and objective multimodal machine vision were used. The salt content in the hams was decreased from 3.4% to 1.4%, and 25% of the Na+ was replaced by K+. The salt reduction had highest influence on the sensory attributes salty taste, after taste, tenderness, hardness and color hue. The multimodal machine vision system showed changes in lightness, as a function of reduced salt content. Compared to the reference ham (3.4% salt), a replacement of Na+-ions by K+-ions of 25% gave no significant changes in WHC, moisture, pH, expressed moisture, the sensory profile attributes or the surface lightness and shininess. A further reduction of salt down to 1.7–1.4% salt, led to a decrease in WHC and an increase in expressible moisture.publishedVersio

A comparison of methods for analyzing multivariate sensory data in designed experiments - A case study of salt reduction in liver paste

This paper presents a comparison of different methods for analyzing designed experiments. The methods used are based on PCA, PLS and ANOVA, used either separately or in combination. Special emphasis will be on how to obtain information about medium and less important factors in the presence of very dominating ones. It will be shown that this could be done by splitting the dataset in two. Our propositions will be illustrated on a data set obtained for studying the effect of salt reduction in liver paste.submittedVersio

Reduction of salt in haddock mince: Effect of different salts on the solubility of proteins

Due to negative health effects of high sodium intake, it is recommended to reduce the daily salt intake by around 50%. To reduce the sodium content, sodium salts can be exchanged with potassium or magnesium salts. The effect of sodium, potassium, and magnesium chlorides on extractability of proteins from fresh and frozen haddock muscle and minces was studied. Salting with KCl and MgCl2 instead of NaCl changed protein extractability. The highest solubility of the proteins was achieved using Na+. However, at low concentrations, extractability in K+ and Mg2+ is on the same level as Na+, showing that partial substitution of NaCl with KCl or MgCl2 is possible. Freezing affected the structure of tissue and protein properties, resulting in decreased amount of salt soluble proteins.acceptedVersio

Reduction of salt in haddock mince: Effect of different salts on the solubility of proteins

Due to negative health effects of high sodium intake, it is recommended to reduce the daily salt intake by around 50%. To reduce the sodium content, sodium salts can be exchanged with potassium or magnesium salts. The effect of sodium, potassium, and magnesium chlorides on extractability of proteins from fresh and frozen haddock muscle and minces was studied. Salting with KCl and MgCl2 instead of NaCl changed protein extractability. The highest solubility of the proteins was achieved using Na+. However, at low concentrations, extractability in K+ and Mg2+ is on the same level as Na+, showing that partial substitution of NaCl with KCl or MgCl2 is possible. Freezing affected the structure of tissue and protein properties, resulting in decreased amount of salt soluble proteins

Traceability of hides through the supply chain - Norilia Hide Case

This study is a part of iProcess project funded by the Research Council of Norway (NFR 255596). The aim of this study was to evaluate various data capture technologies for traceability of hides in a pilot setting. The RFID enabled hide tags provided best readability while there were challenges with the other technologies. RFID tags were used for tracking between the slaughterhouse and Skjeberg. Hides which had dot peening and laser engravings went through the tanning process and the hides returned still had hair on them which made it difficult to read the markings. The UHF and LF RFID tags could not be located in the hides after the tanning process. In theory, all tags and markings tested in the study should be readable, but the tanning process is the main challenge for the available technology. Traceability from the farm to the raw hide processor (Skjeberg) is possible with the technologies available and RFID tags provide promising results. lf the machine-readable requirement is not essential, laser engraving can be used for traceability also including the tanning process.publishedVersio