<div> <p>Thermal processing is a critical step in shelf-stable food manufacturing to the ensure safety of the food products. To accurately model and establish the thermal processes, temperature-dependent thermal properties are needed. Existing methods for measuring the temperature-dependent thermal diffusivity (α), thermal conductivity (k) and volumetric heat capacity (C) are time consuming, tend to have high errors, and cannot provide results in a single experiment, especially at temperatures above 100°C. A novel bench scale device, named Thermal Properties Cell (TPCell), was custom made to rapidly estimate the temperature-dependent thermal parameters of food products. </p> <p> </p> <p>The TPCell used thin film heaters as the heating elements. The first study focused on estimating the thermal properties of a thin film heater. Using mathematical modeling and sequential parameter estimation, the effective thermal diffusivity of the thin film heater was found at different temperatures. The estimated thermal properties of the thin film heater were used for the second study.</p> <p> </p> <p>The objective of the second study was to design optimal complementary experiments using TPCell. Complementary experiments are a combination of experiments that enable estimation of multiple thermal parameters from the experimental temperature data, based on sensitivity analysis. Sensitivity coefficients indicate the extent of change in a measured variable due to a change in value of an input parameter. Designs of experiments were simulated and their impact on sensitivity and optimality criteria was analyzed. Results from the simulated profiles were validated using sweet potato puree. </p> <p> </p> <p>Learnings from this work can be directly applied for the optimization of all types of food thermal processes, including retort and aseptic processing. Optimally designed processes increase preservation of the heat labile nutrients, color, flavor, and taste compounds, thereby enhancing the quality of food products.</p> </div> <br>

Identifying and detecting health hazards in food products, especially contaminants and toxic substances such as allergens, food toxins and agricultural residues from pesticides, remains a challenge. Increasing demand for food products and growing health consciousness necessitate rapid and accurate measurements which can be easily conducted on-site without long measurement times and high costs. Due to their ease of use, accuracy sample preparation and rapidity, biosensors have started to outcompete time-consuming lab-scale analytical devices. However, as the use of biosensors increase, a concern of the amount of plastics and synthetic polymers used in the fabrication of these biosensors rises. In this dissertation, new ways to create biodegradable and eco-friendly plant-based SERS biosensor platforms from corn protein, zein, are presented. Its higher hydrophobicity and film forming capability make zein a very suitable biopolymer for fabricating biosensors. In the first part of this dissertation, chemical crosslinking was tested to improve the surface hydrophobicity, surface roughness (using AFM), mechanical properties, kinetics of gelation and film formation of zein films, and as a result zein-film based SERS platforms with fewer defects could be fabricated. In the second part, the detection sensitivity of the zein film-based SERS platforms was increased with metallic nanoparticle decoration (gold, silver or silver-shelled-gold). The addition of all three types of nanoparticles significantly increased the SERS enhancement factors of the platforms, with silver-shelled-gold nanoparticles giving the highest enhancement factor of 10⁵. In the last part of this thesis, a novel approach was tested, where electrospun zein nanofibers decorated with metallic nanoparticles were used as a SERS biosensor platform. Due to their higher surface area-to-volume ratios, electrospun zein nanofibers gave a higher SERS enhancement factor (10⁶). This enhancement factor enabled the detection of acrylamide, a food carcinogen, with a 10⁴ times lower detection limit than nanophotonic based nanoimprinted zein, acrylamide sensor platform. Overall, this dissertation successfully shows the fabrication of biodegradable and eco-friendly SERS sensor platforms that have comparable detection sensitivities to those of non-biodegradable ones.

<p>Fouling is a critical issue in commercial food manufacturing. Fouling can cause biofilm formation and pose a threat to the safety of food products. Early detection of fouling can lead to informed decision making about the product’s safety and quality, and effective system cleaning to avoid biofilm formation. In this study, a Non-Intrusive Continuous Sensor (NICS) was designed to estimate the thermal conductivity of the product as they flow through the system at high temperatures as an indicator of fouling. Thermal properties of food products are important for product and process design and to ensure food safety. Online monitoring of thermal properties during production and development stages at higher processing temperatures, ~140°C like current aseptic processes, is not possible due to limitations in sensing technology and safety concerns due to high temperature and pressure conditions. Such an in-line and noninvasive sensor can provide information about fouling layer formation, food safety issues, and quality degradation of the products. A computational fluid dynamics model was developed to simulate the flow within the sensor and provide predicted data output. Glycerol, water, 4% potato starch solution, reconstituted non-fat dry milk (NFDM), and heavy whipping cream (HWC) were selected as products with the latter two for fouling layer thickness studies. The product and fouling layer thermal conductivities were estimated at high temperatures (~140°C). Scaled sensitivity coefficients and optimal experimental design were taken into consideration to improve the accuracy of parameter estimates. Glycerol, water, 4% potato starch, NFDM, and HWC were estimated to have thermal conductivities of 0.292 ± 0.006, 0.638 ± 0.013, 0.487 ± 0.009, 0.598 ± 0.010, and 0.359 ± 0.008 W/(m·K), respectively. The thermal conductivity of the fouling layer decreased as the processing time increased. At the end of one hour process time, thermal conductivity achieved an average minimum of 0.365 ± 0.079 W/(m·K) and 0.097 ± 0.037 W/(m·K) for NFDM and HWC fouling, respectively. The sensor’s novelty lies in the short duration of the experiments, the non-intrusive aspect of its measurements, and its implementation for commercial manufacturing.</p>

Introduction ‘Conference’ pear is a climactic autumn pear with unpredictable storage capacity. By studying the storage capacity of the pears, insights can be obtained which can reduce food waste. Aim The aim of this thesis is to study the storability of conference pears in refrigerated temperature against room temperature after longterm storage in modified atmosphere. The study compares conventionally and organically grown pears. Material and methods Organic and conventional Conference pears were studied in refrigerated and room temperature during a three week period. Every other day 5 pears were taken from each test group (organic in cool and room temperature, conventional in cool and room temperature). The pears went through a series of tests which measured weight, color, firmness, brix and pH. As a sensory study, a consensus test was made where pears were assessed by a panel according to predetermined attributes in seven-grade scales. Results The result shows that Conference pears stored at room temperature lost more weight than Conference pears stored in cool during the test period. The pH value dropped for all pear groups while Brix levels decreased for pears stored in cool, but increased for pears stored in room temperature. All pears developed a darker color throughout the test period, both internally and externally. Conventionally grown pears retained it’s green color best in cool storage compared to organically grown peras, but developed a yellow tone instead. All organic pears were perceived to develop a grainier texture and a more brownish color than conventional pears. Conclusion The shelf-life of Conference pears became shorter in room temperature compared to the refrigerated temperature after long-term storage in modified atmosphere. With the exception of the pears starting values, the ripening behavior of organic and conventional pears are similar except that the conventional pears developed a more yellow color over time and the organic pears developed a more brown color instead.

<p>In dairy processing, dairy ingredients need to be thermally treated to ensure product quality and safety for an extended shelf life. During thermal processes, milk protein denatures and interacts with other dairy ingredients to form a layer of deposit on heated surfaces, known as fouling which can deteriorate process efficiency and product safety. Milk is a complex mixture of proteins, fats, carbohydrates, minerals and vitamins. The heat-sensitive B-lactoglobulin (B-lg) is known to be a key component in fouling formation (constituting 50% of type A fouling deposits) during milk pasteurization, as B-lg unfolds when heated and exposes the reactive sulfhydryl groups that can interact with other proteins and ingredients to form deposits. Although casein (80% of milk proteins) is known to interact with denatured B-lg, no fouling studies have been performed with particular focus on the effect of casein on whey protein fouling.</p><p>Carbohydrates are an ingredient widely added in various dairy products as sweetener, stabilizer, texturizer, and fat replacer. Simple sugars have a protective effect on whey protein denaturation, but their effect on dairy fouling is not known. Polysaccharides can interact with milk proteins through electrostatic and hydrophobic interactions, as well as hydrogen bonding. The addition of polysaccharide (carrageenan) has been reported to cause opposite effects on protein deposition, however, no conclusive mechanism has been proposed to elucidate how protein-polysaccharide interaction at pasteurization temperatures affects the fouling behavior of dairy products.</p><p>In this dissertation, different model dairy solutions and real dairy products were used to study the effect of composition, including protein distribution and additions of simple sugars and polysaccharides, on dairy fouling. Fouling deposits were formed and analyzed using a bench-top spinning disc apparatus operating under well-controlled temperatures and shear stresses characterized by computational fluid dynamics simulations. By studying the fouling behavior of camel milk and comparing with bovine milk, milk without B-lg was found to still foul and form deposits containing casein, α-lactalbumin, serum albumin with a reduced thermal resistance due to a more porous structure. Results also showed that the addition of 10 wt% sugar reduced whey protein fouling by more than 30% and affected the structure and adhesion strength of deposits. Furthermore, the presence of carrageenan in dairy solutions can promote the denaturation of B-lg when heated and form a more compact deposit, resulting in more severe fouling. Overall, this dissertation provides a fundamental understanding of the fouling characteristics of complex dairy products. The knowledge gained is expected to help the dairy industry select suitable ingredients to mitigate or prevent the fouling problem.</p>

<p> Fouling is one of the main problems in the food processing industry. The formation of fouling generates complications that could significantly impact the cost of production due to a reduction in heat transfer capacity or sanitation problems. Fouling formation inside enclosed systems can also lead to the growth of biofilms, causing food safety hazards. The fouling layers are firmly attached to the food contact surface of the equipment in ultra-high temperature (UHT) systems where a food product gets sterilized. Clean in place (CIP) is the most common process for cleaning and removal of fouling as it reduces cleaning time, chemicals, and water consumption compared to a regular cleaning out of place process. While cleaning and solids removal, microbubbles (MB) have shown improvement by enhancing the interaction of the components in the cleaning process with the source of contamination. Therefore, a novel pilot-scale microbubble-based CIP (MBCIP) technology was used for cleaning of fouled surfaces and compared to the traditional CIP process in terms of efficiency and reduction in water usage. The fouling layers attached to the food contact surface of the equipment in UHT was the main area examined. The research evaluated the fouling created at 110ºC in sections of stainless-steel pipes heated in a convection oven and at 121 ºC during regular processing in a UHT with coil heat exchangers system. Reconstituted Non-fat Dry Milk Powder (NFDM) was used as the primary source of protein to evaluate the cleaning efficiency. CIP factors were combined with temperatures at 21.11 ºC, 43.33 ºC, and 76.66 ºC, together with water, alkali, and acid, respectively. The optimal conditions for MBCIP were established and applied to a pilot-scale UHT system representative of a commercial-scale UHT system. The sequence of the CIP was water, alkali, water, acid, and water. The results showed that the acid solution at 76.66 ºC with microbubbles had a significantly higher protein removal compared to the rest of the evaluated conditions, removing 72% of the initial protein content compared to alkali and water which were 10 and <2.55%, respectively during 60 minute of CIP. During the full CIP with the combination of water, alkali, and acid, the effect of alkali was significantly higher than in the rest of the steps performed individually. With the addition of MB overall, CIP removed a considerable amount of protein (>21.5%) in a UHT system compared to the traditional CIP method within the 60 minutes period. CIP chemicals were the main factor contributing to the protein removal, and the gas content was the second most crucial factor in determining the removal. The addition of MB will have a meaningful impact when interacting with cleaning chemicals for industrial CIP. MB also occupies a very small amount of space inside the pipelines representing <0.05% of the volume fraction of the fluid inside the pipes, nevertheless, it can potentially reduce water consumption and provides a sustainable cleaning method for the food industry </p>

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Undersökningens målsättning var att utveckla en sås baserad på torkat baobabfruktkött. Baobab är ett träd som främst växer i Afrika och både fruktköttet, kärnorna, bladen och barken kan användas som livsmedel eller örtmedicin. Frukten har ett högt näringsinnehåll av både makronutrienter och mikronutrienter. Torkat fruktkött utvunnit från baobabfrukten användes för att skapa en stabil emulsion som smaksattes för att passa som sås till en vegansk havre/algburgare. För att undersöka vilka smaksättningar som konsumenterna gillar utfördes ett gillandetest i en matbutik. Dessutom användes en semi-tränad panel för att utföra ett beskrivande test med havre/algburgare och baobabsås. Havre/algburgarens smakprofil hade utvecklats från tidigare projekt av Aventure AB. Det beskrivande testet undersökte hur baobabsåsens smak, pH-värde och viskositet påverkar havre/algburgarens smakprofil. Undersökningarna visar att konsumenterna föredrar en sås baserad på en emulsion med lägre viskositet och att de inte gillade en neutral baobabsås. Konsumentundersökningen visade även att när baobabsåsen sväljs resulterar det i en sämre munkänslan som kan bero på de olösliga partiklarna i baobabfruktköttet. De olika smaksättningarna av emulsionerna påverkade havre/algburgarens sensoriska profil olika, den sudanska smaksättningen maskerade smaken och doften av alg medan den neutrala emulsionen ökar intensiteten av brända doften och den brända smaken i havre/algburgaren. / The study will provide a sauce based on dehydrated baobabpulp. Baobab is a tree mostly grown in Africa of which the pulp, kernels, leaves and bark can be used for food applications or as herbal medication. The fruit has a high nutritional value of both macronutrients and micronutrients. During the study, dried pulp extracted from the baobab fruit was used as an emulsifier and flavoring of a sauce adapted for a vegan oats/kelpburger. In order to investigate which flavor the consumers prefer and to determine the taste of the end product, an acceptance test is carried out in a grocery store. A semi-trained panel was used to perform a descriptive test with oats/kelpburger and baobab emulsion. The sensory profile of the oat/kelpburger were developed from a previous project av Aventure AB. The descriptive test examined how the baobabsauce taste, pH and viscosity of affect the sensory profile of oats/kelpburger. The studies show that consumers prefer a sauce based on an emulsion with a lower viscosity and do not like a neutral baobabsauce. Upon swallowing, the level of liking of texture decreases and this may be due to insoluble particles in the baobabpulp. The different flavorings of the emulsions affected the oat/kelpburger's sensory profile differently, the Sudanese emulsion masked the taste and aroma of kelp while the neutral emulsion increased the intensity of the burnt taste and aroma of the oat/kelpburger.

Färdiglagade måltider för specifika målgrupper ställer höga krav på både utseende av maten och förpackningsalternativ så råvaror tillagas så bästa och mest näringsrika vis.  Detta arbete studerar skillnaden i smak och textur mellan två olika konserveringsmetoder av en färdiglagad musselsoppa genom att förpacka i en mikrovågsförpackning och en ångförpackning.  Enkäter för att undersöka skillnad i utseende på soppan gällande musslor med och utan skal genomförs även och där också en jämförelse av kulturell påverkan i våra matval, hur noga man är med hygien när det kommer till mat och deltagarnas generella matintresse för att göra en jämförelse av svenska och franska deltagare.  Syftet är att genomföra en sensorisk optimering av en musselsoppa som utvecklats för äldre konsumenter. / There are high demands on readymade meals when it comes to both the look of the food and the way the meal is packaged to ensure the produce is cooked in the best and most nutritious way. This rapport is about seeing if there is a difference in taste and texture between two different conservation methods for a premade mussel soup. A survey to see if the soup is more appealing if served with the mussels in their shell or deshelled was made and also an comparison of a cultural input on the food choices, how important the hygiene is when it comes to food and the participants overall food interest to get an overall comparison of Swedish and French participants the aim is to complete a sensory optimization of a mussel soup which was developed for old aldults.