Browsing by Subject "ultrasuodatus"

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.

Apples are one of the most eaten and processed fruits in the world. For example, in apple juice production, proportion of the main side stream, apple pomace is 25–35%. It contains mainly carbohydrates and little bit of protein and fat, which makes it unsuitable for feed purposes. Nevertheless, carbohydrates are commonly extracted by water extraction for further purposes of use. Membrane separation is an interesting possibility to fractionate molecules of different sizes from aqueous solutions, for example with ultrafiltration (UF) lactose is separated from whey in dairy industry. Advantages of membrane separation include low energy consumption, low environmental impacts and no phase change. Main limitation for the use of membrane separation process is fouling of membranes, which means that there is a decrease in permeation as a function of time. Aims of the study were to 1) optimize parameters for the membrane separation method by using model solutions in order to get good yield from the process and to 2) separate carbohydrates from apple pomace using water extraction and membrane separation method. Model solutions were used for determining of UF functionality. Sucrose model solutions (SMS) had three different concentration 1, 6 and 11% and pectin-sucrose model solutions (PSMS) had the same concentrations with a pectin addition of 0.5%. These were used to optimize transmembrane pressure (TMP) and concentration for apple pomace extract runs. Apple pomace originated from mixed variety of Finnish apples. Apple pomace was stored in freezer until needed. It was first homogenized by a colloid mill, and carbohydrates were extracted with water extraction in three different apple pomace to water ratios (w/w) with constant extraction time and temperature (80 min/30 ˚C). Three parallel extractions and UF runs were performed for each of the ratios (1:30, 1:10, 1:2 double extraction). Based on the results of the UF runs of model solutions TMP of 4.5 bar was applied for these runs. Samples were taken from original feed solution (weighed solution without the water from the equipment), running solution (after 5 min relaxation time, includes the water from the equipment), permeate and retentate, and from these sugars were analysed with UPLC, dry matter was determined by freeze drying and flux and fouling were calculated. Lower concentration and higher pressure resulted in higher flux (L m-2 h-1) in UF. Presence of bigger compounds, such as pectins, slowed down the experiment and thus, flux. Apple pomace extract runs followed the same principal of higher concentration leading into slower process. The yield of water extraction from dry matter in apple pomace varied between 35 to 65%, the highest yield originated from the pomace to water ratio of 1:30 (w/w). Sugar analysis showed that the permeate from apple pomace extracts contained mostly fructose (average in all of the nine runs 57.4% ± 1.8), sucrose (21.8% ± 3.9) and a little bit of glucose (13.3% ± 1.2) and malic acid (7.4% ± 2.2). In summary, combination of efficient homogenization of raw material by a colloid mill, conventional water extraction and UF of water extract proved to be successful for carbohydrate extraction from apple pomace. Modelling concluded that lower concentration and/or higher pressure leads into higher flux in the process. The whole UF process is slower if there is pectin in the feed solution.

Cheese-making is one of the largest areas of milk processing. Due to large quantities of cheese produced, the decline in milk production and the tightening of environmental legislation, more efficient dairy processes are being developed with the target of full utilization of the raw material. For these reasons, solutions based on membrane technology are becoming more common in the dairy industry. Moreover, membrane techniques allow rationalization of the existing processes and the manufacturing of entirely new products. The purpose of this study is to examine the possibilities of using ultrafiltration in the production of spreadable cream cheese based on scientific articles and studies and by performing pilot-scale experimental research. Under this study, spreadable cream cheese was produced from standardized, fat-containing quark. The whey was separated by ultrafiltration instead of the traditional centrifugation method. A co-company’s pilot-scale membrane filtration equipment was used to produce both light cream cheeses and normal-fat cheeses. The quality characteristics of these samples were compared to a commercial product with chemical analyses and various structural measurements. In addition, the sensory properties of all the samples were evaluated by a consumer test. In this study, differences were observed between the pilot-samples and the reference samples, in both the light cream cheeses and the normal-fat cheeses. The most obvious differences were found in the results of structural measurements. These differences are likely to be explained by chemical composition of the samples, in particular in regard to the fat content. In the consumer test, the reference samples were also estimated to differ from the pilot-samples by several quality characteristics. All in all, this study gives significant information for the co-company’s new process method. Based on the results of this research the co-company was able to move on to industrial-scale test runs.