Browsing by master's degree program "Magisterprogrammet i livsmedelsvetenskaper"

In instantization milk powders’ reconstitution properties are improved. Typical instantization processes are agglomeration, in which particle size and porosity are increased, and lecithination, in which powder particle surface is made less hydrophobic. Both instantization methods have some drawbacks: Agglomeration is not sufficient for instantizing high fat milk powders, while lecithination tends to decrease powder’s flowability. The aim of this study was to review suitability of agglomeration in instantizing milk powder (SMP) and whole milk powder (WMP). Powders were agglomerated on fluid bed agglomerator by using different binder liquids. The physical properties, like wettability, flowability and particle size, of the agglomerated powders were characterized and compared to the unprocessed raw materials and reference powders (commercial instantized milk powders). According to the results reconstitution properties were improved more when using other binder liquids than only water. The fastest wetting on agglomerated SMP was achieved with sugar binder liquids. However, sugar also impaired powders’ flowability. On agglomerated WMPs fastest wetting occurred with phospholipid fraction as a binder liquid. Future research could investigate usage of different binder liquids in combination and optimizing agglomeration parameters for each binder liquid.

3-Chloro-1,2-propanediol (3-MCPD), 2-chloro-1,3-propanediol (2-MCPD) and 2,3-epoxy-1-propanol (glycidol) and their fatty acid esters are contaminants formed during processing fat containing foodstuffs at high temperatures. Mainly MCPD and glycidyl esters have been found to be formed in the deodorization process of oils, and in vegetable oils, such as palm oil, they have been measured at high concentrations. In accordance with the restrictions imposed by the European Commission, the levels of glycidyl esters must be especially monitored, as they have been identified as potentially carcinogenic compounds. The aim of the study was to introduce and validate a gas chromatographic analysis method for glycidyl esters and MCPD esters for the Customs Laboratory. The method was validated for two matrices: first for oils and then for powdered infant formulas. In addition, the success of the validation was examined by analyzing various oil samples previously received by the Customs Laboratory. The Customs Laboratory is also involved in the activities of the European Union Reference Laboratory, for which it was intended to participate in the reference measurement organized by the EU Reference Laboratory. The method for the determination of 3-MCPD, 2-MCPD and glycidyl esters in oils and infant formulas was carried out according to the guidelines of the European Union Reference Laboratory for Contaminants (EURL-PC). Determination of MCPD and glycidyl ester concentrations in oils and infant formulas included the following steps: fat extraction by liquid-liquid extraction (for infant formulas), addition of standards, solid-phase extraction, conversion of glycidyl esters to 3-MBPD esters, transesterification, neutralization, salting out, derivatization and analysis with gas chromatography-mass spectrometry system. Concentrations were determined using internal standard method. The method was validated for the following parameters: specificity, selectivity, limit of detection and quantitation, reproducibility, repeatability, trueness, linearity and working range, stability and measurement uncertainty. The analytical method developed for the determination of MCPD and glycidyl esters was successfully validated for oils and powdered infant formulas. The developed method proved to be specific and selective. The limit of determination was found to be 6.3 µg/kg, 1.3 µg/kg and 0.8 µg/kg for the oil matrix 3-MCPD, 2-MCPD and glycidyl esters. The limits of determination for the infant formula were 5.4 µg/kg, 3.0 µg/kg and 1.6 µg/kg for 3-MCPD, 2-MCPD and glycidyl esters. Recoveries for MCPD and glycidyl esters in the oil and powdered infant formulas were 83-105%. R2 for calibration lines were greater than 0.99, and the lines were linear over the entire measurement range of 2-1000 µg/kg. The relative standard deviation of repeatability and reproducibility was less than 20% for both matrices. The expanded measurement uncertainty for the MCPD and glycidyl esters of the oil and powdered infant formula was less than 50%. For all parameters, the requirements set by the Customs Laboratory and the performance requirements of Regulation (EU) 1881/2006 were met. A method validated for two matrices can then be accredited. The customs laboratory may use the developed method in the future to control 3-MCPD, 2-MCPD and glycidyl esters levels of oils and powdered infant formulas. In the future, the method could also be validated for new matrices, such as liquid infant formulas.

Vacuum-packed frozen meat is popular for its longer shelf life and convenience. However, the quality and safety of these products can be compromised if the packaging material does not provide adequate protection from external factors such as oxygen, evaporation, and light. The objective of this thesis was to assess the feasibility of switching packaging materials for frozen vacuum-packed products at the case company to achieve complete recycling of packaging materials. Biochemical and sensory analysis was carried out on two different pork meats (minced shoulder and top side) packed in four commercially available packaging materials, two of which had an oxygen barrier and two had virtually no oxygen barrier. The top side samples were injected with salt and phosphate brine. All samples were stored in the freezer at -18°C for a storage period of 0-3 months. The analyses were carried out one day after both thawing and cold storage (+4°C). The top side had a storage period of two-weeks and minced meat one-week in the cold room after the thawing. Samples were analysed for TBARS, Thiols, colour, pH, and weight loss. The thiol and TBARS values, pH, a* values and weight loss were measured at different frozen storage times immediately after thawing, and after the cold storage. The results showed that frozen storage time resulted in a reduction in thiol concentrations and an increase in levels in all samples. The cold storage of samples at zero month did not influence thiol concentration, but after frozen storage samples showed a decrease in thiol concentrations. Samples packed in M1 and M2 packaging materials had less thiol content and less TBARS (P < 0.05). There were no differences in the pH of the samples packed in different packaging materials (P > 0.05). The red colour in samples packed in M1 and M2 materials were higher than in samples packed in M3 and M4 materials, but this was only in the case with minced shoulder samples and not with the top side samples. In samples packed in M1 and M3 samples the weight decreased considerably more than in samples packed in M2 and M4 samples (P < 0.05). Change in packaging material for frozen vacuum-packed frozen meat products is not advised to M3 and M4 materials. Forth considering is the choice between M1 and M2, where differed in weight loss during the frozen storage in favour of M2.

Tämän tutkielman tavoitteena oli tuottaa Propionibacterium freduenreichii -bakteerin ja Rhizopus -homesienen yhteisfermentaatiolla B12-vitamiinia härkäpavusta valmistettuun tempeen. Samalla tutkittiin, mitä aminohappoja ja orgaanisia happoja tempeissä vapautui fermentaation aikana ja vaikuttivatko ne B12-vitamiinin tuottoon. B12-vitamiinia sisältävien kasviperäisten elintarvikkeiden tuottamisen tutkiminen on tärkeää, sillä se helpottaisi vegaanista ruokavaliota noudattavien mahdollisuuksia saada B12-vitamiinia ravinnostaan. Hypoteesina oli, että B12-vitamiinia saataisiin härkäpaputempeihin, mutta oletettavasti sen pitoisuuteen valmiissa tempeissä vaikuttaisi käytetty propionibakteerikanta. Ensin kasvatettiin fermentointiin käytetyt propionibakteerikannat ja valmistettiin tempenäytteet härkäpavusta. Valmiista tempeistä määritettiin pH, kosteuspitoisuus, B12-vitamiini, vapaat aminohapot, orgaaniset hapot ja ammoniakki sekä propionibakteerien ja enterobakteerien määrät. Neljästä propionibakteerikannasta kaksi tuottivat tempeen huomattavia määriä B12-vitamiinia (1 µg/g kuivapainoa kohti). Fermentaation aikana vapaiden aminohappojen pitoisuus lisääntyi kaikilla kannoilla valmistetuissa tempeissä selvästi. Eri aminohappoja vapautui kuitenkin eri kannoilla hyvin eri määriä. Maitohappo kului näytteistä fermentoinnin aikana. Pelkällä Rhizopus -homesienellä valmistetussa näytteessä maitohapon määrä taas lisääntyi. Tämä oli tiedettävästi ensimmäinen kerta, kun tutkittiin härkäpaputempen valmistusta Rhizopus -homesienen ja propionibakteerin yhteisfermentaatiolla B12-vitamiinin tuottamiseksi. Tutkimus antoi lupaavia tuloksia B12-vitamiinipitoisen tempen valmistuksesta, sillä härkäpaputempejen vitamiinipitoisuudet olivat huomattavasti suurempia kuin mitä aikaisemmissa tutkimuksissa soija- ja lupiinitempeillä homesienen ja propionibakteerin yhteisfermentaatiossa saadut vitamiinipitoisuudet.

Hexanal is a highly volatile liquid that can prolong the shelf life of fruits and vegetables (Paliyath and Subramanian 2008). Previously, Lehtonen et al. (2020) introduced a freeze-dried active packaging material which was continuously releasing hexanal through the naturally occurring lipid oxidation reactions of sunflower oil. In this study, nine different sunflower oil-based matrices were characterized at different stages of their preparation process. They contained crystallization modifiers (acylglycerols, phytosterols, or their blend), coating materials (gum Arabic and maltodextrin), and were produced by spray-drying of an emulsion. The crystallization modifiers in the matrix may enable the control over the start of the reaction for hexanal release. The emulsions with crystallization modifiers were significantly unstable, their viscosity increased with an increasing proportion of gum Arabic, and they contained crystalline regions from the first day of preparation. All tested emulsions formed a white powder after spray drying and the powder particle sizes were characterized. The differential scanning calorimetry (DSC) did not reveal any melting point of the lipid phase in majority of the powder samples. However, the DSC results showed that the melting temperatures of corresponding oleogels with acylglycerols and acylglycerol/phytosterol blend were 64 and 56.6 °C, respectively. In this thesis, emulsions containing acylglycerols and/or phytosterols were characterized and shown to be suitable for the encapsulation by the spray drying technique. Further studies focusing on the hexanal release from the matrix need to be performed since no hexanal release was detected from the powder samples.

The objective of the research was to compare collagen characteristics, general meat quality parameters and carcass characteristics of three different muscles from freely pasturing Mangalitza Red breed and highly bred domestic/commercial pig breed. Collagen content and collagen solubility was analyzed by hydrolyzing the three different muscle samples. Meat quality parameters were analyzed previously by Natural Resources Center (Luke). The pH of Mangalitza LD muscle varied from 5.41 to 5.64, SM muscle from 5.53 to 5.75 and IS muscle from 5.74 to 5.87, IS having higher pH than the two other muscles (P < 0.05). The pH of commercial pig LD muscle varied from 5.47 to 5.75, SM muscle from 5.52 to 5.77, and IS muscle from pH 5.96 to 6.51, IS having higher pH than the two other muscles (P < 0.05). Breed had effect on pH of muscle IS (P < 0.05), but no effect on muscles LD or SM (P > 0.05). The color of muscles of Mangalitza was darker than commercial pig’s in all the three muscles (P< 0.05). In Mangalitza, LD was lighter than SM and IS, but in commercial pigs, LD and SM were lighter than IS (P < 0.05) Collagen content of all three muscles of Mangalitza differed from each other (P < 0.05) and the collagen content of LD and SM were lower (P < 0.05) than of commercial pig’s collagen content. In commercial pig, collagen content of LD and SM muscles were lower than in IS muscle (P < 0.05). Collagen solubility of all three muscles of Mangalitza differed from each other (P < 0.05) and the collagen solubility of SM and IS were lower (P < 0.05) than of commercial pig’s collagen solubility. In commercial pig, collagen solubility of LD and SM muscles were lower than in IS muscle (P < 0.05). In contrast to collagen content, collagen solubility of LD muscles did not differ between the breeds (P > 0.05). The amount and solubility of collagen did not deviate from normal; it can be concluded that this study did not provide any new information other than the collagen content and solubility of Mangalitza Red breeds muscles of LD and SM.

Cronobacter spp. are opportunistic human pathogens. They can cause infections in infants and illness in older children and adults. There is also a high case fatality rate. Cronobacter spp. are found in dried foods, such as powdered infant formulas and Cronobacter spp. have caused serious cases of infection in worldwide. Therefore, Cronobacter spp. should not be present in powdered infant formulas that reach consumers. Cronobacter do not survive heat treatment. It is therefore likely that Cronobacter will migrate to the product from the environment or from heat-sensitive nutrients added after pasteurization. The data for the study was collected from the production control systems of the powder plants. Data was used for the period 2018-2020. Two powder plants, Plant A and Plant B were compared. Cronobacter results of environmental were compared with different climate variables using regression analysis, for example. Statistical analysis was performed with Minitab software. It was investigated whether the positive Cronobacter results were related to the microbiological results in the products. One subject of the review was whether seasonal variability was present in Cronobacter environmental samples. It was also examined whether explanatory factors were found for the Cronobacter results of individual targets. Based on the results of the study, there was no clear relationship between positive environmental sample results and weather conditions. Seasonal variation is also unrelated to environmental sample results. There was no statistical association between positive Cronobacter environmental results and microbiological results of the products. When examining the sampling targets, most of the positive results were found in the floor sampling targets. Based on the results, it would be a good idea to consider whether it is necessary to make changes in the hygiene areas or tighten the hygiene requirements. The use of additional shoe covers should be on option, for example. The prevention of Cronobacter in the environment is particularly important. Possible contamination of the products poses not only health risks but also financial damage. Rejection of production batches due to Cronobacter contamination can be economically significant.

Gas chromatography (GC) is one of the most widely used method for analysis of lipids and it is commonly combined to a flame ionization detection (FID), since GC-FID is an excellent combination for quantitative analysis of wide range of lipids. Before GC analysis can be performed, lipids must be extracted from the sample and derivatized. Some common extraction methods include Soxhlet and Soxtec extraction, Folch extraction and extraction with the help of acid hydrolysis. To be able to analyse the extracted fatty acids by GC, they must be in a volatile form. This can be achieved by forming fatty acid derivatives by, for example, methylation. The commissioner wishes to have a way to analyse the fatty acid composition of pork by GC in their laboratory. The aim of the study was to take in use an easy, safe-to-use and simple method for determination of fatty acid composition of pork by gas chromatography, using the instruments and equipment already found from the laboratory. The research had three different parts. First, heptane-isopropanol extraction, Bligh & Dyer extraction and Caviezel extraction were compared. Then the chosen extraction method was validated. Finally, two different pork samples were compared to test the method’s ability to differentiate them. Caviezel extraction was chosen as the best extraction method, and it was validated by parameters repeatability and robustness. The method was able to differentiate samples that had similar, but slightly different fatty acid compositions. However, method still requires some fine tuning since the GC column seemed to be highly sensitive to any disturbances.

This master thesis aimed to develop a calibration model of the whipping cream for FTIR spectrophotometer MilkoScanTM FT3 and identify the effects of disruptive factors on whipping cream measurement. In the previous calibration model of whipping cream, there could be improvements in the level of the results, especially for lactose. The experimental part of this research included the development of a calibration model, calibration of lactose, total solids assay, and calculation of measurement uncertainty. The calibration model was developed utilizing the statistical methods PCA and PLS in the FossCalibrator program. Lactose calibration was carried out with the LactoSens method, utilizing whipping cream and α-D-lactose, and the results from the reference laboratory were used as reference. The accuracy and functionality of the calibration of total solids wanted to verify, which was why the experimental part included the total solid assay. Total solids were determined by a gravimetric method, and the results were compared with those of the reference laboratory. The measurement uncertainty of the calibration model was calculated with the results of the whipping cream sample reproducibility, repeatability, and accuracy. The new calibration model of whipping cream was verified utilizing validation samples, and the check results were at the expected level. The result of lactose calibration was considerably more accurate than the previous model. The total solids result from the gravimetric method varied slightly with the FT3 results, which, however, did not affect practically. The measurement uncertainty was relatively good, but the calculation will be improved as the number of reference results increases. The main subject of this research was achieved, i.e., the development of the calibration model was successful. The research on the disruptive factors was less than initially intended.

Cowpea (Vigna unguiculata) is one of the most important legumes in the world due to its high nutritional content. Its nutritional value is, however, hindered by different anti-nutrients, such as phytic acid (PA), which can lower the bioavailability of minerals and proteins. PA is a nutritionally significant compound found in many plant materials, such as cereals and legumes. PA is myo-inositol-1,2,3,4,5,6-hexakis dihydrogen phosphate (IP6) by chemical nomenclature. Measurement of PA is challenging, due to its high charges and its low content, amongst other factors. The primary aim in the thesis was to create an accurate, selective, and sensitive UPLC-QTof-ESI-MS method for quantification of PA from legumes, cereals, and other plant materials. The secondary objective was to determine PA content in raw, fermented and phytase-treated white cowpea flour and investigate the effectiveness of the processing methods on PA hydrolysis. PA content in white cowpea has been previously determined with methods lacking the capability to directly measure only PA content, without also adding in the concentration of smaller inositol phosphates (InsP) or other phosphorus containing compounds. Therefore, the presumption was that the measured PA concentration should be lower when using the selective UPLC-QTof-ESI-MS method. Besides white cowpea flour, the concentration of PA in red cowpea, wheat bran, sorghum, wheat fraction and rapeseed protein concentrate flours was also measured to investigate if the method works for other plant matrices as well. The sample preparation method consisted of two-hour extraction in 0.5 M HCl, a neutralization step, lyophilization, reconstitution with 5% MeOH and addition of adenosine 5′-monophosphate monohydrate (AMP) as internal standard. The samples were then analyzed with UPLC-QTof-ESI-MS, with electrospray ionization on negative ion mode (ESI-). The PA quantification method had excellent precision, selectivity, repeatability, and linearity (R2 = 0.991). Accuracy was good and the recovery of 100% resulted in a high level of trueness. The LoD was determined as 3.22 µg/mL but could be possibly lowered. The PA content in white cowpea flour was 5.91 mg/g dry weight. As was presumed, this result was lower than previously reported in literature. The method was also relatively suitable for the other plant samples. However, wheat fraction, rapeseed protein concentrate, and sorghum flours gave unexpected results. In the fermented sample the PA content was 3.30 mg/g and in the enzyme-treated 0.09 mg/g (or 12.4 µg/mL). However, the fermentation and enzymatic treatments did not reduce the PA concentration under the threshold of <3.3 µg/mL, where iron cation chelation still strongly takes place. The processing method could be improved by increasing the phytase dosage or increasing the reaction times to achieve higher hydrolysis of PA.