Browsing by discipline "Livsmedelsteknologi"

The purpose of this study was to investigate the structure of ice cream, especially the effects of temperature, sugar composition and stabilizer-emulsifier concentration on the melt down, hardness and moulding properties of ice cream. The aim was to produce a soft and easily mouldable ice cream that suits the intended purpose. A sensory evaluation was conducted to the ice creams with desired structural properties. The literature review deals with ice cream ingredients, manufacturing process and factors affecting ice cream structure. For the experimental study, 16 ice creams with different compositions were made. The ice creams contained 12 or 6 % fat, different types of sugar compositions (A, B, C, D, E, F) and different concentrations of two types of stabilizer and emulsifier blends (A, B). Ice creams were stored at different temperatures. The hardness of ice cream was measured with a Texture Analyser, the melting rate was determined and the moulding properties were analysed with a moulding test. The two ice creams with desired structure were compared to a commercial ice cream in a sensory evaluation. The results of the hardness measurements revealed, that temperature and sugar composition affected hardness the most. Stabilizer and emulsifier concentration and type did not have an effect. The softest ice creams were those stored at higher temperatures and those made with sugar composition C, D, E and F. The slowest melting ice creams were the ones containing greater amounts of stabilizers and emulsifiers. The ice cream made with sugar composition D melted the fastest. For the moulding test, the softer ice creams were the easiest to mould. The ice cream made with sugar composition D was found to be too soft, almost runny, and the ones made with sugar composition A and B were found to be too hard. The ice creams made with sugar composition C, E and F were found pleasing. The batches containing a greater amount of stabilizer and emulsifier were found to be a bit gummy. In the sensory evaluation there were only one difference in sweetness found between the study ice creams and the commercial one. There were no differences found in creaminess and over all liking. From this can be concluded that the study ice creams are accepted by the consumers as well.

Iodine is an essential nutrient for humans and it is needed for the synthesis of thyroid hormones. Approximately 1,5 billion people in the world are suffering from iodine deficiency. In Finland, mild iodine deficiency has occurred in adults according to national surveys. The recommendation of iodine intake is 150 µg/day for adults. According to the National FinDiet 2017 survey, iodine intake of men was at the recommended level, but women had mild iodine deficiency. The most important sources of iodine are cereal products and dairy products. Iodized table salt is the most important source of iodine as a single ingredient. Iodized salt is added to several foods, but iodine loss may occur. Loss of iodine can be caused by several factors, for example heat treatments, storage conditions and processing. The objective of this thesis was to investigate the use of iodized salt in Finnish food industry and find out the amount of iodine in food products that contain iodized salt. The stability of iodine was also studied. The iodine intake in Finnish population was estimated. The use of iodized salt in Finnish food industry was investigated mostly with Foodie-website and food manufacturers’ websites. Iodine concentrations from 112 food products in different food categories were analyzed by inductively coupled plasma mass spectrometer (ICP-MS) at Finnish Food Authority. The iodine intake in 2012 and 2017, was estimated for different population groups. The consumption data of different food groups were from the National FinDiet 2012 and 2017 surveys. The iodine content of different foods were from analyzed food samples and Fineli-database. Two kinds of calculations were done: with and without iodized salt. There are many categories, where most of the manufacturers use iodized salt: breads, convenience foods, sauces, cold cuts and sausages. The amount and stability of iodine varied between different food products. Calculated and analyzed iodine content varied between different food products and food categories. There was big difference in iodine intake, depending on if calculations were done with or without iodized salt. For example, for 18–44 years old women in 2017, the iodine intake was 228 µg/day with iodized salt and 88 µg/day without iodized salt. The use of iodized salt in the Finnish food industry seems to be at a good level, but there are differences between categories. The amount and stability of iodine in food products varies a lot, but it was seen that there is still significant amount of iodine in processed food products. Iodized food products have a major effect on the iodine intake of Finnish population. There is still no concern about excessive iodine intake at the iodine concentration 25 mg/kg NaCl. Finnish food industry should continue using iodized salt, because it is an efficient way to prevent iodine deficiency in Finnish population.

Jogurtin valmistuksessa ultrasuodatus (UF) on mahdollinen vaihtoehto maitojauhe- tai maitoproteiinilisäykselle. Tutkielman kirjallisuusosiossa perehdyttiin maidon ultrasuodatusprosessiin ja jogurtin proteiinipitoisuuden nostamisen eri vaihtoehtoihin. Kokeellisessa tutkimuksessa pyrittiin selvittämään, voidaanko jogurtin proteiinipitoisuutta säädellä hallitusti hyödyntämällä valmistuksessa ultrasuodatettua maitoa. Kiinnostuksen kohteena oli se, että aiheuttaako maitoproteiinijauheen korvaaminen ultrasuodatetulla maidolla muutoksia jogurtin laadussa. Kokeellisen tutkimuksen aikana valmistettiin rasvattoman maidon ultrasuodatuksella saaduista retentaatista ja permeaatista rasvatonta ja 2 % rasvaa sisältäviä sekoitejogurtteja. Jogurtit valmistettiin eri proteiinipitoisuuksilla niin, että ne vastasivat konsentraatiokertoimia 0,9, 1,1, 1,2, 1,4 ja 1,6. Näiden lisäksi valmistettiin vertailutuote, jossa tarvittava maitoproteiinipitoisuus saavutettiin lisäämällä rasvatonta maitoproteiinijauheetta. Jogurttimaidot fermentoitiin kolmen kaupallisen hapatteen, A1, A2 ja A3, avulla. Näytteet valmistettiin kahtena tutkimussarjana. Ensimmäisessä sarjassa jogurtit valmistettiin kolmella eri proteiinipitoisuudella (konsentraatiokertoimilla 1,1, 1,2, 1,4) ja toisessa sarjaan lisättiin 0,9 sekä 1,6 konsentraatiokertoimet. Valmistetuista jogurteista mitattiin synereesi, pH-arvo ja konsistenssi vuorokauden, 1 viikon ja 2 viikon kylmäsäilytyksen (6 °C) aikana. Näytteitä seurattiin myös aistinvaraisesti ja toiseen tutkimusvaiheeseen sisältyi tuotteiden fermentointiaikainen pH-arvon seuranta. Maitoproteiinijauhelisäyksellä valmistettu ja samalla proteiinipitoisuudella ultrasuodatuksen jakeista valmistettu jogurtti eivät eronneet merkittävästi aistinvaraisessa arvostelussa. Jogurttimassojen laktoosipitoisuudessa ennen fermentointia esiintyi eroja niin, että maitojauhelisäyksellä valmistetussa jogurttimaidossa oli enemmän laktoosia kuin jakeista valmistetuissa jogurttimassoissa. Niin rasvattomien kuin 2 % rasvaa sisältävien jogurttinäytteiden kohdalla nopeiten fermentoitui kaikilla kolmella hapatteella maitojauhelisäyksellä valmistettu massa. Korkeammalla proteiinipitoisuudella olevat massat (konsentraatiokertoimilla 1,4 ja 1,6) saavuttivat tavoite pH-arvon 5 ja 5,5 tunnissa. Kylmävarastoinnin aikaisen heran erottumisen mittauksista havaittiin, että niin rasvattoman kuin 2 % rasvaa sisältävän jogurttimassan 4 (konsentraatiokerroin 1,4) heran erottuminen oli pienintä verrattuna muihin massoihin kaikilla kolmella hapatteella valmistetuissa jogurteissa. Sama massa erottui myös jogurttien konsistenssimittauksissa.

Tutkielmassa perehdyttiin kuumennuskäsittelyn vaikutukseen kauran ja ohran pelkistäviin yhdisteisiin. Lisäksi selvitettiin pelkistävien yhdisteiden toimintamekanismeja happiradikaalien muodostajana ja happiradikaalien toimintamekanismeja polysakkaridien pilkkojana. Kokeellisen työn tavoitteena oli verrata erilaisten kuumennuskäsittelyjen vaikutusta kauran ja ohran beetaglukaaniuutteiden pelkistävien yhdisteiden pitoisuuksiin ja selvittää oliko erilaisilla kuumennuskäsittelyillä tai pelkistävien yhdisteiden pitoisuudella vaikutusta beetaglukaaniuutteiden viskositeetin säilymiseen varastoinnin aikana. Tutkimuksessa käytettiin kuumentamattomia ja 95 °C:ssa 70, 100 ja 130 minuuttia kuumennettua kauraa ja ohraa, joista tehtiin lisäksi jauhonäytteet, jotka pestiin etanolilla pelkistävien yhdisteiden poistamiseksi. Jauhoista tehtiin rinnakkaiset uutteet, joista toisia kuumennettiin 90 °C lämpötilassa 5 minuutin ajan ja toisia uutteita ei kuumennettu. 100 minuuttia kuumennetuista jyvistä tehdyillä uutteilla verrattiin myös uutteen kuumennuskäsittelyn keston vaikutusta viskositeetin säilymiseen, pidentämällä uutteen kuumennusta 5 minuutista 15 minuuttiin. 130 minuuttia kuumennetuista jyvistä tehdyistä uutteista tehtiin lisäksi näyte, jota kuumenettiin 130 °C sterilointilämpötilassa 10 minuutin ajan. Kaikki kuumennuskäsittelyt pienensivät pelkistävien yhdisteiden pitoisuuksia molemmilla viljoilla. Kuumennuskäsiteltyjen kaurajauhojen pelkistävien yhdisteiden pitoisuudet alenivat noin puoleen ja ohrajauhoissa noin kolmasosaan kuumentamattomaan, natiiviin jauhoon verrattuna. Natiivien jauhojen etanolipesu pienensi pelkistävien yhdisteiden pitoisuuksia kaurauutteissa 45 % ja ohrauutteissa 36 % verrattuna ei etanolipestyistä jauhoista tehtyihin uutteisiin. Ei-etanolipestyistä jauhoista tehtyjen uutteiden pelkistävien yhdisteiden pitoisuus oli molemmilla viljalajeilla sitä pienempi mitä kauemmin kuumennetuista jauhoista uutteet oli tehty. Kuumennuskäsittelyajan pidentäminen 70:stä 130:en minuuttiin pienensi kaurauutteiden pelkistävien yhdisteiden pitoisuutta tilastollisesti merkitsevästi. Kaurauutteiden kuumennusajan pidentäminen nopeutti viskositeetin pienenemistä varastoinnin aikana. Sterilointilämpötila romahdutti viskositeetin 10 minuutissa. Paras uutteiden viskositeetin pysyvyys saavutettiin kauran- 130 minuutin ja ohranjyvien 100 minuutin kuumennusajalla, ja kun uutteet oli tehty etanolipestyistä jauhoista. Vaikka jauhojen etanolipesun ja kuumennuskäsittelyn osoitettiin vähentävän merkittävästi jauhojen pelkistäviä yhdisteitä, eivät ne olleet teknologisesti riittäviä toimenpiteitä ylläpitämään beetaglukaani-vesiseoksen viskositeettia stabiilina varastoinnin aikana.

The aim of the study was to optimize growth media and its composition for one Lactobacillus strain. The purposes of the optimized culture media for fermentation were to maximize cell count and amount of viable cells during processing. The raw materials for growth media had to be suitable for industrial use. The study was performed by Bioscreen and fermentation tests in different growth media. At first ability of the strain to grow was tested by Bioscreen C with different raw materials and their compositions. According to literature, six carbon, four nitrogen sources and three other raw material were chosen to Bioscreen tests. Bioscreen C measured turbidity (OD value) of cultivation. According to the results from Bioscreen tests, optimal raw materials were chosen to the fermentation tests. The optimal carbon sources were whey permeate powder and glucose, the optimal nitrogen sources casein peptone and yeast extract and other raw materials manganesulfate, magnesiumsulfate and yeast extract. The cultivations were made in a bioreactor (Biostat Q). The starter strains were concentrated and freeze-dried. Samples from cultivated, concentrated and freeze-dried starter strain were analyzed (cell counts, optical density, growth rate, base consumption and survival-%). Results were compared to those obtained using control medium that is known to support the growth of the Lactobacillus strain. Lactobacillus strain was able to grow in different growth media. In Bioscreen tests compositions of growth media have major effect on lactobacilli growth. Bioscreen experiments revealed that in most cases the Lactobacillus strain grew to higher OD values in the composed media compared to control medium. In Bioscreen tests the sugar based growth media required more added minerals and yeast extract than whey permeate based media. Yeast extract was found to promote Lactobacillus growth in Bioscreen tests. In fermentation tests cells grew on growth media equally as on control media. Suitable alternative options for growth media were found from tests for further studies. Further studies can research functionality of the raw materials in production scale and preservation of the cell concentration during storage.

Propionibacterium freudenreichii is a dairy propionic acid bacterium and it is used as adjunct culture in Swiss-type cheese manufacture. The bacterial strain is known for its GRAS (Generally Recognized as Safe) status, and it is safe to use in food. Based on previous studies, P. freudenreichii requires anaerobic conditions to start bacterial growth. Bacterial viruses ‘bacteriophages’ uses two life cycles, lysogenic or lytic cycle. The life cycle of bacteriophages affects bacterial cell lysis or division. Researchers are interested in fortifying foods naturally with vitamin B12. P. freudenreichii is known for its ability to actively produce vitamin B12. This master's thesis aims were to study 1) The effect of oxygen contentration on Propionibacterium freudenreichii subsp. freudenreichii JS7 strain and 2) the effect of oxygen consentration on the prevalence of bacteriophage in P. freudenreichii JS7 strain. In this study, P. freudenreichii JS7 strain was grown at different oxygen concentrations. Bacterial growth was observed by cell density measurements and cell plating. In the preliminary experiment, the strain was grown 1) anaerobically 2) two stages which includes aerobic and anaerobic growth conditions and 3) aerobically. Based on the partial results of the preliminary experiment, the fermentation was performed in a bioreactor in an anaerobic growth condition. The cell plating results of the bioreactor experiment were used to study the effect of oxygen concentration on the presence of bacteriophage in a bacterial strain by using three primer pairs. The polymerase chain reaction was applied to study the presence of the bacteriophage genome as a plasmid, free, and prophage which means that phage genome is integrated into the bacterial chromosome. Based on the results of this study, the cell density of P. freudenreichii JS7 strain increases faster in anaerobic oxygen concentration comparing to aerobic and two staged oxygen concentrations. Based on the results of the bioreactor study, the bacterium can anaerobically form different size of colonies for the cell plating. The bacteriophage genome may be present as a plasmid, free and integrated into the bacterial chromosome. The results of the bacteriophage study might give signs that P. freudenreichii JS7 could be able to utilize the lysogenic life cycle in anaerobic growth condition.

Tutkielman kirjallisuuskatsauksessa perehdyttiin kauraan ja härkäpapuun raaka-aineena. Lisäksi tutustuttiin intialaiseen riisistä ja mustasta linssistä fermentoinnin avulla valmistettuun idli-höyryleipään ja sen valmistusprosessiin. Tutkielman kokeellisen osan tavoitteena oli selvittää soveltuvatko kotimaiset kaura ja härkäpapu idlin valmistusprosessiin. Idlin raaka-aineet korvattiin osittain tai kokonaan kauralla ja härkäpavulla. Lisäksi tutkittiin heräteviljelmän käyttöä taikinan ja valmiin höyryleivän ominaisuuksien kannalta. Osa taikinoista fermentoitiin idlin valmistusprosessin mukaan spontaanisti ja osaan lisättiin startteriksi leivinhiivaa tai viiliä. Taikinoiden viskositeetit mitattiin ennen fermentointia. Fermentoitumista mitattiin taikinan tilavuuden muutoksen, pH:n ja happoluvun avulla. Höyryleivistä määritettiin paistohäviö, korkeus ja sisuksen kovuus heti sekä seitsemän vuorokauden säilytyksen jälkeen. Valmiiden höyryleipien ravintosisältö ja välttämättömien aminohappojen koostumus laskettiin perustuen kirjallisuusarvoihin. Härkäpapu-riisi- ja härkäpapu-kaura -taikinat fermentoituivat spontaanisti. Härkäpapu-riisi -taikina fermentoitui härkäpapu-kaura -taikinaa tehokkaammin. Härkäpapupitoisuus nosti molempien taikinoiden happolukua fermentoinnissa. Taikinaan lisättävällä viilillä tai leivinhiivalla voitiin säädellä taikinan tilavuutta, ja sitä kautta vaikuttaa höyryleivän tilavuuteen, huokoisuuteen ja kovuuteen. Härkäpavusta ja riisistä oli mahdollista valmistaa rakenteeltaan hyvä höyryleipä. Härkäpapu ja kaura tuottivat ominaisuuksiltaan erilaisen, rakenteeltaan ei-huokoisen ja tiiviin höyryleivän. Kauraa sisältävät höyryleivät säilyivät pehmeämpänä kuin riisiä sisältävät. Raaka-aineiden suhdetta muuttamalla saatiin aikaan erilaisia höyryleivän rakenteita höyryleivän proteiinilaatua heikentämättä. Lähes kaikki höyryleivät ylittivät FAO:n asettamat vertailuarvot välttämättömien aminohappojen määrissä. Idli-prosessilla fermentoidut kaura ja härkäpapu soveltuvat höyryleivän lisäksi myös muiden ravintoarvoiltaan laadukkaiden ruokavalmisteiden pohjaksi.

Food trends and the prevalence of gluten-free diet have increased the use of oats in pastry in recent years. However, wheat has not been replaced by oats alone, substitutes are often mixtures containing buckwheat and potato starch, among others. The flour used for sponge cakes is weak wheat flour. Next to flour, the main raw materials for sponge cake are egg and sugar. Eggs produce an aerated structure of the cakes. The purpose of this study was to use as much oat as possible in sponge cake without losing the characteristic structure of the product. In the preliminary experiments, it was found that it was possible to replace wheat flour fully by oat endosperm. When the oat flour contained bran, the characteristics of the sponge cake changed significantly. Other preliminary tests were per-formed with the use of full oat flours with different particle size. Endosperm oat and whole oat flours were selected for a maturing time test to examine the effect of flour disintegra-tion on the finished product. Texture- and moisture measurements were performed. Prod-ucts of the same oat flour were also manufactured in production scale. Texture- and hu-midity measurements, as well as the changes over time were captured. In addition, a con-sumer test and a descriptive analysis of the products were carried out by a trained taste panel. The study showed that wheat flour can be replaced by oat endosperm or full oat flour with a particle size of about 390 μm. The results of the preliminary investigation showed that it is possible to produce a sponge cake with full oat flour with almost the same characteristics as the product has when made with wheat flour, only the oat product was perceived a little dryer. The sensory profile on full oat flour sponge cakes showed more brittleness, the addition of bran made the biscuits even more brittle. Longer maturing time improved the properties of the product in every flour type tested. The best way to replace wheat flour by oat is using only oat endosperm.

The literature review focused on the chemical composition of oats, the functional properties of oat components and the foods manufactured from oat ingredients. The factors affecting the technological and the nutritional properties of oat β-glucan have been previously studied. However, the effect of enzymatic hydrolysis on oat β-glucan has not been widely examined. The aim was to study the effect of β-glucanase concentration, hydrolysis time and temperature on the hydrolysis rate of oat β-glucan. During the experimental work an Arena-method was developed to analyse the concentration of β-glucan. The required amount of experiments was determined using statistical CCF design of experiment. The total number of experiments was 36 and 96 analyses were conducted in the experimental work. The viscosity, the concentration of β-glucan and the concentration of dietary fibre were analysed from the hydrolysed suspensions. Based on the results, the effects of the process variables on the hydrolysis of β-glucan were evaluated. Hydrolysis of β-glucan was a relatively fast reaction with the β-glucanase used in the study. Hydrolysis temperature and the concentration of the enzyme had the most significant effects on the hydrolysis of β-glucan. Based on the viscosity curves, the molecular weight of oat β-glucan was significantly decreased. The hydrolysed β-glucan did not increase the viscosity and was not indicating shear-thinning behavior. However, most of the β-glucan hydrolysates were dietary fibre by definition.

In this thesis snack production and oats as a raw material for snacks were reviewed. Oat lipid oxidation and the shelf life of snack products made of oats was also considered. The aim of experimental studies was to find out if it is possible to puff baked snacks in the oven with high temperature without using yeast as a leavener. The test was conducted with two different baking temperatures and with and without added yeast. The shelf life of oat-based snacks with spice extract were also studied for 12 months by sensory evaluation. Lipid oxidation was also measured, and the product quality was determined by microbiological tests. Also, two consumer tests (number of panelists n = 30 and n = 118) were made with the snacks. Statistically there were no difference between two baking temperatures in doughs with yeast, but the higher temperature decreased the average error of snack samples heights. Yeast in the dough was significant. Sensory evaluation panel recognised the hidden, freshly baked reference sample from the actual samples at 6 months’ time. The results from the measurements of lipid oxidation on the effect of spice extract on snacks shelf life wasn’t clear and needs further investigation. The products microbiological quality stayed good the whole time monitored.