Ronit Mandal¹ and Anubhav Pratap-Singh^{1
1 Food, Nutrition and Health, University of British Columbia, Vancouver BC, V6T1Z4, Canada}

Abstract
Pulsed UV light (PL) treatment is a light-based non-thermal process for food decontamination. For designing a PL process for liquids, sample clarity is an important factor governing process efficacy. Thus, it would be interesting to study the treatment of opaque liquid foods like milk. Milk (0%) and distilled water were inoculated with Escherichia coli ATCC 29055, Listeria innocua 33090 and Clostridium sporogenes 7955 and treated in continuous mode by UV254 dose of 22.22-322.22 J/L in annular reactor and 36.36-1148.63 J/L in coiled reactor. Milk (0% and 3.25% fat) were treated under same PL condition and tested for color, vitamin B2 and C, protein and lipid oxidation. Inactivation was higher in coiled reactor, where milk (0%) showed >3, ~ 3, and up to 3 log10 CFU reduction of E. coli, L. innocua and C. sporogenes, respectively. Sample clarity effect was evident as, for water, almost a 3-fold inactivation was achieved in all cases compared to milk. The color parameter b* decreased with treatment intensities. Vitamin B2 decreased significantly with treatment. Vitamin C reduced by ~35 % for both types of milk. However, there was no significant lipid and protein oxidation.

Practical relevance
Pulsed UV light process is still in infancy. Optimizing the treatment conditions for treatment of milk will help in gaining regulatory approval and therefore wide commercialization by food industry alike other non-thermal processes like High-pressure processing.

Miguel Aguilera Toro¹, Valentin Rauh², Yinghua Xiao², Lisbeth Truelstrup Hansen³, Nina Aagard Poulsen¹, Lars Wiking¹ and Lotte Bach Larsen^{1
1 Aarhus University, Foods Science Department, Denmark
2 Arla Foods, Denmark
3 Technical University of Denmark, Food Microbiology and Hygiene Research Group, Denmark}

Abstract
One of the main problems in UHT milk is its spoilage by exogenous enzymes. Enzymes produced by Pseudomonas (proteases and lipases) are considered the lead cause, due to their production at low temperatures and the resistance against high-temperature treatments.

In order to gain knowledge about the intricateness of the process, enzyme-producing strains have been cultured on a minimal medium with the presence of UHT milk to induce enzyme secretion. The enzymes were later extracted from the culture medium and inoculated into UHT semi-skimmed milk. These samples were exposed to a shelf-life storage experiment where their pH, protein content, proteolytic activity, sediment/gel formation and protein profile were studied.

Results from this experiment showcased the high heterogeneity that exists between bacterial species. The enzymes from Pseudomonas panacis consistently showed the highest proteolytic activity and fastest sedimentation formation (1-2 weeks). An initial increase, and quickly decrease afterwards, of the pH curve was observed on those strains that showed increasing proteolytic activity. The next step would be to look at environmental samples and their genetic organization.

Practical relevance
The knowledge generated in this project will help to understand better the spoilage of UHT milk by bacteria. This knowledge will allow the dairy industry to be more efficient when handling, processing, storing and distributing UHT milk. Additionally, the optimization of the production of UHT milk will reduce the volume of wasted product and the overall environmental impact.     

Ozgenur Coskun¹, Lars Wiking¹, Saeed Rahimi Yazdi² and Milena Corredig^{1
1 Aarhus University, Department of Food Science, Denmark
2 Arla Innovation Center, Arla foods, Denmark}

Abstract
With microfiltration (MF) it is possible to change the ratio of ions, lactose and soluble proteins in milk concentrates. In this study, micellar casein concentrates (MCC) were obtained with MF at 10°C, with the help of extensive diafiltration (DF) against water. Samples were brought to 2x concentration, then subjected to extensive DF, keeping the volume fraction constant. The concentration was then continued to a 4x final concentration. Total and soluble protein content quantified by Dumas. The soluble phases and permeates were analyzed by RP-HPLC. Overall, β-casein transmitted along with whey proteins in all stages of MF with a total protein transmission calculated as 62% and 34%, for whey proteins and β-casein, respectively. All the main caseins, κ-, β-, α_s1- and α_s2-, were found, in the serum phase. The ratio of the individual to total casein increased with DF. Interestingly, there was no statistical difference between LDF and HDF ratios. Furthermore, the colloidal calcium concentration decreased from 1816 to 1676 mg/L after extensive DF. These molecular changes occurring during the process affected the functional properties of the MCCs.

Practical relevance
Milk protein concentrates are classified not by how they are produced, but by their total protein content. However, this work brings evidence that knowing the molecular details change depend on the processing history, can lead to a higher quality of MCCs and an increase in processing and utilization efficiency by targeting their end use.    

Anne Katrine Laursen¹, Tijs Albert Maria Rovers², Richard Ipsen¹ and Lilia Ahrné^{2
1 Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
2 Arla Innovation Centre, Arla Foods, Agro Food Park 19, DK-8200, Aarhus-N, Denmark}

Abstract
Consumers are searching for possibilities to reduce their lifestyle carbon-footprint. An existing dairy-based meat alternative is the indigenous Indian heat- and acid-induced cheese type paneer. In order to investigate utilization of cow milk in the production of attractive meat alternatives cow and buffalo milk paneer were compared in terms of composition, microstructure and texture. Cow and buffalo milk standardized to a fat content of 3, 4.5 and 6% for paneer production. The milk was heated to 90°C and hold for 0, 6 or 12 min, before acidification at 85°C and pressing. Demonstrated through confocal laser scanning microscopy (CLSM) cow milk paneer showed a more open protein structure compared to buffalo. This resulted in a softer, less cohesive and resilient paneer compared to buffalo. The difference in protein content and thus calcium content had a major influence on the microstructure and texture, as a higher content of total calcium in the paneer resulted in a denser and harder gel. The hardness of both cow and buffalo milk paneer was affected more by the fat content, and thus lower protein content, than the length of the heat treatment.

Practical relevance
In terms of industrial application, this work suggest that altering the fat content and controlling calcium mobility of cow milk offers the possibility to modify paneer texture to produce attractive meat alternatives.

Emilie Nyborg Nielsen¹, Leif H. Skibsted¹, Saeed Rahimi Yazdi², Arthur Merkel³ and Lilia Ahrné^{1
1 Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg, Denmark
2 Arla Foods Amba, Agro Food Park 19, 8200 Aarhus N, Denmark
3 MemBrain s.r.o. (Membrane Innovation Centre), Pod Vinicí 87, 471 27 Stráž pod Ralskem, Czech Republic}

Abstract
Acid whey is a side-stream from the production of skyr, Greek yoghurt, quark and cottage cheese. It contains high concentrations of valuable minerals, which are essential in the human diet such as calcium. Electrodialysis has recently shown to be an efficient way to isolate charged components from acid whey, however, its composition highly affects the demineralization degree (Nielsen et al., 2021). Acid whey contains calcium-binding components such as citrate, lactate, gluconate and sugars that have different affinities to calcium and consequently influence the removal of calcium during electrodialysis. This study investigates the removal of calcium ions in model solutions containing lactose, glucose, glucose/galactose mixture, lactate, gluconate or citrate by electrodialysis in order to identify the importance of bounded and free calcium on the efficiency of demineralization.  The effect of pH and concentration are also evaluated for selected calcium binding components.

Nielsen, E. N., Merkel, A., Yazdi, S. R. & Ahrné, L. (2021). The effect of acid whey composition on the removal of calcium and lactate during electrodialysis. International Dairy Journal, 117, 8 p., 104985.

Practical relevance
Knowledge about calcium binding components effects on removal of calcium ions during electrodialysis of acid whey is important to select pretreatments of the whey and optimizing the demineralization rate during electrodialysis.    

Ran Feng¹, Sylvain Barjon¹, Franciscus Winfried J van der Berg¹, Søren Kristian Lillevang² and Lilia Ahrné^{1
1 University of Copenhagen, Denmark
2 Arla Foods, Denmark}

Abstract
To manufacture mozzarella cheese with customized functionality, the relationships between processing parameters and cheese functionality need to be identified. In this study, cooking residence time (CRT) and stretching residence time (SRT) of cheese curd in the cooker-stretcher were determined to differentiate the effect of the cooking and stretching processes on cheese properties. In the stretcher used, CRT was significantly longer  than SRT, varying respectively between (62-90%) and (38-10%) depending on cheese temperature and screw speed. The residence times were correlated with cheese composition, micro- and macro-structural characteristics (microstructure, fat globule size, anisotropy and rheology) and functional properties (meltability, oiling-off, browning and stretchability). Linear correlations were found between CRT and cheese composition, anisotropy and storage modulus. In general, SRT had a less significant effect on cheese properties and functionality, which is due to the low specific mechanical energy of 0.15-0.46kJ/kg. It was concluded that CRT and SRT are promising factors to understand and control the cheese characteristics during manufacture.

Practical relevance
Understanding the effects of water temperature and screw speed, and their interactive effects, on the residence times in the cooker-stretcher. And the consequences for mozzarella cheese composition and functional properties provide relevant knowledge to produce mozzarella with customized functionality.