Browsing by discipline "Food Chemistry"

Folate is a water-soluble vitamin that belongs to the vitamin B group. The most important function of folate is to participate in C1 metabolism, and folate deficiency can lead to megaloblastic anaemia, neural-tube defects or coronary diseases. In Finland the folate fortification of food products is not mandatory and the intake of folate is still too low. Based on previous studies, blue lupin (Lupinus angustifolius) seems to be a good source of folate, especially the Haags Blaue variety, which has shown to be suitable for cultivation under Finnish environmental conditions. The aim of this research was to study if the folate concentration of blue lupin could be increased with germination and fermentation. In addition, the purpose was to examine how these bioprocessing methods would affect vitamer distribution of folates. Three germination experiments were performed, two with seeds that were soaked overnight in water and one with seeds that were soaked in lactic acid solution. The duration was four or five days and the samples were collected daily. The fermentation experiment was performed with kernel flour from non-germinated seeds and kernel flour from seeds that were germinated for two days. The synthesis of folate was studied using two microbes: Streptococcus thermophilus and Saccharomyces cerevisiae. The fermentation with S. cerevisiae yeast was made both with and without glucose addition. Samples were taken at 0 and 24 h. Total folate concentrations of samples were analysed with a microbiological method and the vitamers were analysed with an ultra-high-performance liquid chromatography method (UPLC). The folate concentration of seeds increased 2-fold by germination. The proportion of 5-methyltetrahydrofolate increased significantly during germination, from 60 % in nongerminated kernel flour to 77–88 % in germinated dehulled seeds. S. thermophilus did not produce folates in lupin flours. The folate content of non-germinated flour was increased 1.8-fold by yeast fermentation between 0 and 24 h, and yeast needed the glucose addition. However, glucose addition did not have an impact on folate concentrations of kernel flour from germinated seeds. Germination significantly increased the folate content of lupin seeds, and the greatest proportion of folates were stable vitamers. Stability of vitamers is important for the folates of food products thus germination of lupin seeds appears to be an interesting processing method. On the basis of the fermentation experiment, S. cerevisiae is a promising folate producing microbe when using lupin flour as a matrix. The fermentation experiment should still be repeated and performed using sterilised flour so that the actual production of folate by S. cerevisiae could be studied.

The aim of this Master’s Thesis was to develop a method for determining iodine from food. The method was developed and validated for the Finnish Food Safety Authority Evira. The literature review focused on the chemistry of iodine and its occurrence in nature and food as well as its physiological importance to humans. Different methods used in iodine analyses were also discussed with emphasis placed on ICP-MS. Sample matrices used in the experimental study were milks with different fat contents, egg, cheese and fish. Two different milk powders (BCR®-150 and BCR®-063R) and fish muscle (ERM BB®-422) were used as certified reference materials. Milk and cheese samples were dissolved in 0.5 % ammonium hydroxide, left overnight and shaked for two hours before the analysis. Cheese and fish samples were prepared using microwave digestion with ammonium hydroxide as the reagent. After both sample preparation methods the samples were in 0.5 % ammonium hydroxide which was also used as the rinsing solution of the ICP-MS-instrument. Tellurium was used as an internal standard. Validation parameters determined were method specificity, selectivity, repeatability, reproducibility, accuracy, measuring range, linearity, LOD and LOQ. Measurement uncertainty of the method was also estimated. The method was proven to be specific and selective to measure iodine. The accuracy of the method for egg and milk samples was 90.3% and the recovery of added iodine in these samples was 98.7%. For the fish and cheese sample method these results were 86.9% and 102.3%. Both sample preparation methods gave repeatable and reproducible results. LOQ for the milk and egg sample method was 0.02 mg kg-1 and for the fish and cheese method 0.06 mg kg-1. The expanded measurement uncertainty for all matrices was 10–29%. The validation proved the method to be fit for purpose and reliable. The method will be used for measuring the iodine content of actual food samples.

The literature review focused on the chemistry, uses, occurrence and toxicology of pesticide residues. Emphasis was placed on residue analytics and GC-MS/MS-methods. The aim of this study was to develop a reliable and reproducible GC-MS/MS-multi residue method for the determination of pesticide residues in poultry feed. First, two available sample preparation methods were compared. The methods chosen for comparison were QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) based on dispersive solid phase extraction (dSPE) and a liquid-liquid extraction method. In the former, the residues were extracted with water-acetonitrile mixture and the content of the dSPE tube containing MgSO4 was added to the extract to induce the liquid-liquid partitioning of the residues. The extract was then cleaned with primary and secondary amine (PSA) and octadecylsilane (C18) absorbents, filtered and analysed by GC-MS/MS. Based on the comparison, the QuEChERS method was chosen for the validation experiments. The QuEChERS method was proven to be a quick and simple method that provided better trueness than the other compared method. The repeatability was sufficient for 54 residue compounds. However, the recovery was between 70-120 % for 28 analytes and mainly less than 70 % for the remaining compounds. The limit of quantification was 0.01 mg/kg for 48 analytes. The developed multi residue method can be used for reliable and reproducible determination of 24 pesticide residues in poultry feed whereas the assessment of the method for the remaining compounds will be continued. After a more comprehensive evaluation, the method can be applied for other feed matrices in future multi residue studies.

Puuteollisuus hyödyntää puusta korkean arvon lopputuotteina lähinnä selluloosaa. Ligniinin ja hemiselluloosien käyttökohteita vasta kehitetään. Niiden eristäminen onnistuu ympäristöystävällisesti kuumavesiuutolla ilman liuottimia, jolloin hemiselluloosaan jää sitoutuneeksi myös ligniiniä. Koivun hemiselluloosista tärkein on glukuronoksylaani (GX). Sen mahdollisia jalostustuotteita voisi olla mm. emulgointiaineena toimiminen, jota voitaisiin käyttää elintarvie-, lääke- ja kosmetiikkateollisuudessa tuotteiden hyllyiän pidentämiseksi. Tutkimuksen tavoitteena oli tutkia GX:lla stabiloidun öljy vedessä -emulsion pysyvyyttä ja analysoida emulsion pisaroiden rajapintaa. Pysyvyyttä arvioitiin määrittämällä pisarakokojakauma ja peroksidiluku kolmen kuukauden aikana. Alkuperäisestä materiaalista, emulsion jatkuvasta faasista ja rajapinnoilta määritettiin monosakkaridijakauma GC-FID-laitteistolla ja fenoliset yhdisteet UHPLC-UV/FID-aitteistolla. Fenolisista yhdisteistä tunnistettiin tärkeimmät massaspektrometrisesti. Tämän lisäksi yritettiin fraktioida anioninvaihtokromato-grafisesti galakturonihappoa (GalA) sisältävät fraktiot. GX:n stabiloima emulsio oli pysyvä sekä kemiallisesti että fysikaalisesti. Kolmen kuukauden aikana sen peroksidiluku ei kasvanut merkittävästi, mutta pisarakoko kasvoi. Faasit eivät kuitenkaan erottuneet toisistansa. GX:n tärkeimmiksi fenolisiksi yhdisteiksi tunnistettiin vanilliini ja syringaldehydi. Molempia löytyi jatkuvasta faasista ja rajapinnoilta. Suurin osa GX:n fenolisista yhdisteistä oli sitoutunut polysakkaridiketjuun esterisidoksilla ja glykosidisidoksilla. GX sopisi hyvin elintarvikkeiden stabilointiaineeksi, koska se ehkäisee hapettumista ja emulsiorakenteen hajoamista. GX:n pisaroiden rajapinnalla on sekä esterisidoksia että glykosidisidoksia. Esterisidokset mahdollistavat tiiviin rakenteen ja polysakkaridiketjujen pelkistävässä päässä olevat glykosidisidokset paksun, mutta harvan rakenteen. Myös GalA:n suuri määrä rajapinnalla viittaa siihen, että pektiini saattaa osallistua stabilointiin.

Global food production contributes to 25-30% of total greenhouse gas emissions and the environmental effects of the food system are estimated to even rise 50-90 % by year 2050. A shift to plant-based diets and the use of meat alternatives can address the growing health and environmental problems related to animal-based food consumption. However, off-flavors may limit the utilization of plant-based proteins in food applications by creating challenges concerning sensory quality and consumer acceptance. The aim of this study was to test if LAB fermentation can improve consumer perception of an oat and legume-based product. Furthermore, this study explores consumer perceptions of plant-based protein products, factors related to their consumption and whether flavor of these products might be a barrier to use. The consumer study included a sensory evaluation (N=135) and a web survey (N=1442). In the sensory study consumers evaluated the pleasantness of a fermented plant-based protein product and a non-fermented reference sample in addition to attributes related to odor and taste. Consumer views and attitudes towards plant-based protein products were studied in the web survey. The effects of fermentation on the sensory properties of the plant-based protein product were very small, yet statistically significant. Consumers found the fermented sample to be more pleasant overall and in smell. The odor of the fermented sample was also found less earthy, but the taste slightly more bitter compared to the reference sample. The results suggest that fermentation could be used as a method to reduce earthy flavors of plant-based protein products and thus increase consumer acceptance. Based on the results to the survey, taste, health, environmental impact, ethical reasons, price, domestic origin and easiness to prepare were the most important factors in food choices of the respondents. Characteristics of the participants show that consumers with frequent consumption of plant proteins were overrepresented in the sample so the findings cannot be extended to general population. Overall, the sensory properties of plant-based protein products were perceived as quite pleasant among the respondents and as many as 83 % (N = 1197) agreed that these products taste good. This study presents that flavor and particularly odor of plant-based protein products might act as a barrier to use especially to consumers that are not familiar with these products.

The literature review focused on quinoa saponins, on their extraction, isolation and chromatographic analysis. The aim of this study was to develop a quantitative and qualitative analysis method for saponins in quinoa. Gas chromatograph (GC) was used for separation. Saponin aglycones were indentified by mass spectrometry (MS) and quantified by flame ionization detector (FID). Sample pretreatment included extraction of fat soluble compounds and saponins by accelerated solvent extraction (Dionex ASE). Saponin aglycones liberated by acid hydrolysis followed by liquid-liquid extraction. Aglycones were derivatised to silylethers and analysed with GC-MS/FID. Finally this method was used to analyse saponins in washed and pearled quinoa seeds. Method evaluation included repeatability test (4 separate days, total n = 14). Average, standard deviation, relative standard deviation and Horrat(r) - value were calculated for the results. Method realability was evaluated by recovery test. Known amount of saponin was added to flour samples (n = 3). Additions responded 6, 4 µg, 12, 8 µg and 32 µg hederagenin aglycone. Four saponin aglycones, oleanolic acid (ole), hederagenin (hed), serjanic acid (ser) and phytolaccagenic acid (phy), were successfully identified in all samples by method prescribed. Method was repeatabale for ole and ser quantition but not for hed and phy. Satisfactory recovery, 80 %, was achieved on 32 µg addition level. Recoveries for 6, 4 µg and 12, 3 µg addition levels were 76 and 66 %. Results could be explained by aglycones pH dependent solubility combined to inaccurate pH adjustment after hydrolysis. In the future neutralization step should be revaluated. Washing reduced saponins 20–58 % and pearling reduced 58 % saponins in quinoa seeds. However pearling caused loss of protein from 12, 3 % to 5, 8 %.

Food adulteration is a constantly growing problem in the quality and safety control of food products. In Finland, the Finnish Customs Laboratory is responsible for the control of imported plant based foods. Among other things, challenging economic situation and gaining economic profit can tempt some people to make adultered products. In a worse case adulteration can cause a serious health risk to the consumer. It’s also misleading when the package doesn’t contain truthful information. Particularly berry jams and purées are easy to adulterate since it’s easy to replace the more expensive ingredient partly with cheaper material, which might be impossible to notice by the sensory characteristics. Strawberry (Fragaria x ananassa) is the most popular and produced berry in Finland. Because fresh strawberry has a short growing season and shelf life, a variety of jams, juices and frozen products are made at home and industrially. Large quantities of strawberry products are also imported into Finland, so there may be some fake products among them. Strawberry contains hundreds of volatile and non-volatile compounds, which are resulted of the plant maturation and metabolism. Some of these compounds are unique to each plant species and also known as marker compounds. The primary objective of this study was to examine the suitability of the selected research techniques for identifying adultered jams by analyzing aroma and phenolic profiles of jams and to develop a preliminary qualitative control method for Customs Laboratory. Techniques used were solid-phase microextraction combined with gas chromatography and mass spectrometry (SPME-GC-MS) to analyse volatile aroma compounds and ultra-high performance liquid chromatography combined with mass spectrometry (UHPLC-MS) for determination of phenolic compounds of self made strawberry jam. Phenolic compounds were extracted by ultrasound assisted extraction prior to UHPLC-MS analysis. Fruits and vegetables used in the jam fraud may be for example apple, pear and pumpkin, so the possible marker compounds were analysed also from jams made of these plants. Self-made fake jams were made by mixing strawberry jam (cultivar Polka) with apple (cv. Ida Red), pear (cv. Conference) and pumpkin (cv. Butternut) jams in proportions of 5–50 % to examine the detection of adulteration. Also some commercial products were analysed to evaluate the suitability of the methods to commercial samples. Results were analyzed and studied by repeatability tests of methods and principal component analysis (PCA). Relative standard deviation (RSD) of the SPME-GC-MS method was considerably higher than RSD of the UHPLC-MS method (51 % compared to 10 %) which tells about weak repeatability of the SPME-GC-MS method. Interesting discovery was the observation of phloridzin from the strawberry samples, since phloridzin has been used as a marker compound of apple although similar observation has been reported earlier. To our knowledge this is the first time phloretin xyloglucoside was also observed from strawberry samples. Self-made strawberry, apple, pear and pumpkin jams differed from each other on the basis of aroma and phenolic compounds composition of the studied cultivars. The aroma profile of apple jam and pumpkin jam differed from each other the most. By the phenolic profile strawberry jam was the most different from the other samples. The mixtures of strawberry jam with apple, pear and pumpkin jams in proportions of 5 %, 10 %, 20 % or 50 % were clearly separated from the self made pure jams on the basis of both aroma composition and phenolic composition. The differences between strawberry jam and fake jams were clear even when the reference jam (apple, pear or pumpkin jam) was removed from the PCA. The 5–20 % fake jam mixtures had only minor differences in aroma and phenolic composition, meaning that determination of quantitative differences with the current methods would be challenging. Mixtures of 50 % stood out the most from other fake mixtures. The evaluation of commercial samples was found to be challenging due to the variability factors of the study. Nevertheless both methods were found to be useful for the detection of adulterated strawberry jams made of selected cultivars. The detection of addition of apple, pear or pumpkin jam was already seen at the addition level of 5 %. With some modification and further development both of these methods can be used as quality control methods at Customs Laboratory.

Punaisen värin ruskistuminen on laatuongelma mansikkasoseessa. Mansikan punainen väri on peräisin antosyaaneista, jotka ovat reaktiivisia ja hajoamisherkkiä yhdisteitä. Ruskistumisreaktiot jaotellaan entsymaattisiin ja ei-entsymaattisiin reaktioihin. Kirjallisuuskatsauksessa perehdyttiin mansikan antosyaanien kemiaan ja kartoitettiin mansikkasoseen ruskistumisen eri mekanismit. Kokeellisen tutkimuksen tavoitteena oli selvittää hallintakeinoja mansikkasoseen ruskistumisen estämiseksi. Kokeellinen tutkimus koostui kolmesta osasta: kuumennus-, säilyvyys- ja prosessikokeesta. Kuumennuskokeessa selvitettiin mansikkasoseen kuumennusajan ja värimuutosten välistä yhteyttä sekä tehtiin mansikkaraaka-aineiden vertailu. Säilyvyyskokeen mansikkasosenäytteitä seurattiin kuuden viikon ajan 7 tai 23 C:n lämpötilassa. Prosessikokeessa vertailtiin teollisessa mittakaavassa valmistettujen vadelma- ja mansikkasoseiden värimuutoksia kuukauden ajan. Lisäksi verrattiin kuumennus- ja korkeapainepastörointikäsittelyn vaikutusta mansikan värin pysyvyyteen. Kolorimetrillä tehdyistä värimittauksista määritettiin näytteiden väliset värimuutokset (E*). Värimittauksen lisäksi kaikista mansikkasoseista määritettiin suuntaa antava antosyaanipitoisuus spektrofotometrisellä menetelmällä. Säilyvyyskokeen mansikkasosenäytteiden tarkat antosyaanipitoisuudet ja fenolisten yhdisteiden pitoisuudet määritettiin erittäin suuren erotuskyvyn nestekromatografisella menetelmällä. Lyhyt kuumennusaika (30 s) aiheutti mansikkasoseessa suurimmat säilytyksen aikaiset värimuutokset. Pidemmälla kuumennusajalla (180 s) värimuutokset olivat suurempia kuumennuksen aikana, mutta säilytyksen aikaiset muutokset jäivät pienemmiksi. Kylmäsäilytetty mansikkasose oli näytteistä ainoa, joka ei menettänyt hyväksyttävyyttään säilyvyyskokeen aikana. Prosessikokeessa vadelmasoseen väri osoittautui merkittävästi mansikkasoseen väriä pysyvämmäksi. Korkeapainepastöroidun mansikkasoseen väri oli yhtä hyväksyttävä kuin kuumennetun, mutta rakenteen hyväksyttävyys heikkeni kuukauden säilytyksen aikana. Tulosten perusteella voidaan päätellä, että lyhyt kuumennusaika ei ollut riittävä mansikan endogeenisen entsyymiaktiivisuuden inaktivoimiseksi. Säilyvyyskokeessa ilmeni mansikan antosyaanien suuri hajoamisherkkyys, jota voidaan hillitä vain kylmäsäilytyksellä. Mansikkasoseen kylmäsäilytyksen tarpeellisuus varmistui prosessikokeessa.

Pesticides are used in primary production to protect and strengthen the crops. Many of these pesticides can be analysed with multiresidue analyses, but some of them need a single residue method (SRM). Polar pesticides are an example of these compounds. Because polar pesticides, such as mepiquat, chlormequat and ethephon, have strong polar interaction, small concentration and weak volatility their analysis from vegetable samples is challenging. The target of the literature part of this thesis was to get acquainted with legislation that sets rules and demands for the use of pesticides and their analysis. The target was also to get acquainted with challenges in polar pesticides analysis and the methods that have been used in their analysis. In the experimental part the aim was to develop a new method for analysing mepiquat, chlormequat and ethephon in vegetables and fruits. The reason for developing a new method was a growing demand for a quick, simple, resource saving and selective method. The method was based on the QuPPe-method (Quick Polar Pesticides Method). Four columns that were suitable for analysing polar pesticides and several eluents and gradients were tested. The sample matrices were tomato, grape and apple. UHPLC-MS/MS equipment, which had a liquid chromatograph (Agilent Technologies) combined with a triple quadrupole mass spectrometer, was used. After testing the method was validated. The final method included extraction with acidic methanol, separation of the compounds by hydrophilic interaction chromatography (HILIC) and analysis by a triple quadrupole mass spectrometer. The limit of quantification (LOQ) for ethephon, chlormequat and mepiquat was acquired from the legislation and was based on maximum residue levels of the compounds (MRL, ethephon 0.05 mg/kg, chlormequat 0.01 mg/kg and mepiquat 0.02 mg/kg). The limit of detection (LOD) was for ethephon and chlormequat 0.001 mg/kg and for mepiquat 0.002 mg/kg. The recovery levels for these compounds varied between 92% and 131% depending on the matrix. The relative standard deviation varied between 3% and 63%. Because of the ion suppression, caused by sample matrices, the quantification was done by a standard addition method. The developed method was suitable for analysing ethephon, chlormequat and mepiquat in tomato, grape and apple samples repeatably. The sample preparation was simple and fast, which supports the idea of using this new method for routine analysis. The biggest problems were encountered when analysing ethephon because of its weak signals. The sample matrices tested caused different amounts of signal loss and the biggest loss was found in tomato samples in small concentrations.

Microalgae are the most primitive and simple members of plant kingdom, unicellular or colonial and can be found worldwide. Microalgae are promising organism for producing sustainable biomass and microalgae can be used to produce proteins, lipids, colourants, vitamins and carbohydrates to food industry and can be used as feed for animals and source for biofuels. The objective of this study was to select the most effective extraction solvent and develop and optimize an accelerated solvent extraction (ASE) method for microalgal lipids. ASE is an extraction technique that needs only small amounts of solvents and uses elevated temperature and pressure for better extractability. Study had two separated parts; 1. Choosing the best solvent for ASE, 2. Optimizing extraction conditions. Study was made with two freeze dried biomasses; Euglena gracilis and Selenastrum Sp. Choosing an extraction solvent for ASE was made between acetone, ethanol and 2-ethoxyethanol and those were compared for Bligh and Dyer chloroform- methanol-water solvent extraction. Lipid yields were analyzed as total fat as sum of fatty acid methyl esters and fatty acid composition with GC-FID. Overview of lipidclasses was studied with TLC. Tocopherol analysis was made with NP-HPLC-FLD and carotenoids and chlophylls were analyzed with UV-VIS spectroscopy. Optimizing the extraction conditions was made with experimental design program with 2*15 samples in different extraction conditions with ethanol as solvent. Evaluation of results was made by total fat, omega-3 fattyacids EPA and DHA, tocopherol, carotenoid and chlorophyll contents. Optimized extraction conditions were: Temperature 125 ⁰C, Extraction time 11 min, 1 extraction cycle and Pressure 1500 psi. Temperature had the greatest effect on the studied extraction parameters.