The aim of this work was to study the effect of different concentrations of transglutaminase (TG), inactivated or not inactivated – 0.02, 0.06 and 0.12% (w/w) – on the textural characteristics and ...flow properties of stirred probiotic yoghurt prepared from pasteurized skim milk (0.1% w/w fat). The physicochemical characteristics and the textural and rheological properties of yoghurt samples were determined after production and during 10 days of storage. The gel structure of yoghurt samples produced with not inactivated TG was stronger than that of samples produced with inactivated TG and control sample. Yoghurt containing 0.12% (w/w) TG not inactivated showed the highest hysteresis loop area (3,580 Pa·s) after 5 days of storage. Hysteresis loop area of samples with 0.12% (w/w) inactivated TG after incubation for 2 h at 40C is 56% lower compared with samples manufactured with the same concentration of not inactivated TG after 10 days of storage. PRACTICAL APPLICATIONS: To produce yoghurt with low energy value, improved gel characteristics, and good physical and chemical properties, enzyme transglutaminase (TG) can be used. Enzymes are potential tools to increase the formation of covalent cross‐links in protein foods. The addition of TG can reduce proteins and milk fat to produce nonfat yoghurt with the same rheological characteristic as yoghurt from whole fat milk. There are two different ways for the application of TG: simultaneously or prior to the fermentation. In the first case, TG was simultaneously added with starter culture. Pretreatment of milk with TG addition prior to fermentation demands additional process time as well as thermal inactivation step and has the advantage of a constant pH during the cross‐linking reaction.
The aim of this study was to investigate the effect of transglutaminase (TG) addition on rheological properties, textural characteristics and microstructure of fermented milk products manufactured by ...different starters (probiotics and kombucha inoculum). Rheological analysis revealed that all manufactured fermented milk products had higher storage modulus than loss modulus and exhibited thixotropic and a typical shear thinning behavior. The addition of TG in milk increased approximately 10.5% hysteresis loop area, 39% firmness and 48% consistency in sample produced with probiotic starter and had more firm and stable gel structure than kombucha fermented milk products. The scanning electron microscopy micrographs showed that casein matrix of fermented milk products containing TG is continuous and uninterrupted except for void spaces occupied by milk serum and starter culture cell.
Practical Applications
Transglutaminase (TG) is a transferase that forms inter‐ and intramolecular isopeptide bounds in and between many proteins by cross‐linking of the amino acid residues of protein‐bound glutamine and lysine. Among the dairy proteins, the casein fraction represents a favorable substrate for TG, mainly due to the highly accessible and flexible open chain structure. Heat treatment prior to cross‐linking is necessary because the reactivity of TG is very low in unheated or pasteurized milk, despite the high reactivity of the casein. In the case of low‐fat products, behavior of milk proteins during the gelation process is of particular importance. Cross‐linking of preheated milk with reduced fat content results in improved gel firmness and reduced syneresis of acid‐induced milk protein gels. Also, TG treatment at optimal technological parameters, pH value and temperature of milk, can solve these problems in kombucha fermented milk products, improving firmness, consistency and viscosity of gel.
This paper investigates the manufacture of milk-based beverages by application of several Kombucha starters. Local Kombucha culture was grown up on three substrates: sweetened black and green tea, ...and topinambur. Their concentrates were obtained by vacuum-evaporation and amounts of 10% and 15% (v/v) were applied to milk (2.2% fat). The traditional yoghurt starter (B3) was applied for producing control samples. All fermentations were stopped when the pH reached 4.4. Fermentation curves were registered, linear for yoghurt and sigmoidal for Kombucha. Two times faster process was achieved with yoghurt starter. Influence of inoculum concentration on the rate of fermentation was insignificant. Viscosities were higher for Kombucha beverages at lower speeds of spindle, but lower at higher speeds of spindle. Very high sensory scores were achieved for all beverages, after production and after 5-days’ storage.
The effect of turbulence promotion on cross-flow microfiltration of skim milk was studied experimentally. The use of Kenics static mixer as turbulence promoter in inorganic (Membralox™) membranes ...with pore sizes 50, 100 and 200
nm provided a significant permeate flux improvement. In experiments at the same Reynolds number, the flux improvements of more than 500% were achieved for
Re numbers in the range 3000–10
000. The increase of power consumption for fluid flow due to the insertion of turbulence promoter was also discussed. The effect of turbulence promoter on microfiltration performance was checked at the same hydraulic dissipated power. The flux improvements of more than 300% were achieved for hydraulic dissipated power in the range from 0.13 to 0.95
W indicating that using the turbulence promoter is more energy efficient than operation without the turbulence promoter. The fouling resistance analysis approved that resistance of the surface micellar layer dominates the overall fouling resistance. The use of turbulence promoter caused a large scouring of the membrane surface provided significant reduction of reversible fouling. Also, when the turbulence promoter was used, the membrane cleaning efficiency was improved compared with experiment without the promoter.
Volatile compounds, affecting flavour of traditional and probiotic fresh
cheese, were determined. Functional dairy product-fresh cheese was produced
from milk of 2.5% fat content and milk of 4.2% fat ...content, under the
semi-industrial conditions. The traditional starter culture Flora Danica (FD)
and a combination of probiotic starter ABT-1 and FD (ABT-1:FD=1:1) were
applied as starters. The volatile fractions were isolated by employing the
combined simultaneous distillation-extraction technique (SDE). The compounds
were identified by gas chromatography - mass spectrometry (GC-MS) and
quantified by using standard procedure. Following 19 compounds have been
identified: 8 hydrocarbons (decane, undecane, tridecane, tetradecane,
pentadecane, hexadecane, octadecane and 2, 6, 10, 14-tetramethyl hexadecane);
6 ketones (2-heptanone, 2-nonanone, 2- undecanone, 2-pentadecanone,
2-heptadecanone and 2-tridecanone); 3 aldehydes (nonanal, tetradecanal and
hexadecanal); 1 fatty acid (decanoic acid) and disulfide, bis
(1-methylethyl). The highest levels were associated with hexadecanal,
2-pentadecanone, 2-tridecanone, and 2-undecanone in all examined samples,
regardless to the starter culture and type of milk used.
Novel trends in fermented dairy technology Caric, Marijana; Milanovic, Spasenija; Ilicic, Mirela
Zbornik Matice Srpske Za Prirodne Nauke,
2019, Letnik:
2019, Številka:
136
Journal Article
Recenzirano
Odprti dostop
Novel trends in fermented dairy technology are presented in this review
paper. The application of new starter cultures (probiotics, kombucha), as
well as quality improving ingredients like ...transglutaminase (TGase), milk
protein fractions, and functional components of plant origin have been
investigated by the authors worldwide. New processing techniques such as:
high-pressure processing (HPP), high pressure homogenization (HPH), and
ultrasonic processing (USP) are interesting because of their potential to
achieve a specific and/or novel functionality or to improve the efficiency.
Novel trends in fermented dairy technology contribute to the creation of
various products with high nutritive value, possessing also specific
functional properties. Basic health benefits of functional fermented dairy
products are: biologically active peptides - ACE inhibitors and
antioxidative activity. Due to the mentioned functional characteristics,
these dairy products are considered to be among the most precious functional
foods.
The adsorption of proteins to membrane surfaces can lead to the reduction of a permeate flux and represents a serious impediment to efficient membrane filtration operations. The factors influencing ...protein adsorption, permeate flux and overall membrane fouling during cross-flow filtration of whey protein solutions using 50
nm pore size ultrafiltration zirconia membrane and 200
nm pore size microfiltration alumina membrane were examined in this study. The permeate flux was observed to be a function of protein concentration and transmembrane pressure and followed classic membrane filtration behavior for the membranes studied. Studies of the fouling resistances, coupled with static adsorption studies, indicated that adsorption-related pore plugging plays a significant role in the larger pore alumina microfiltration membranes.
Milk and dairy products are the oldest and most widely consumed nutritious foods worldwide. They are highlighted as a source of high-quality proteins and the most important sources of bioactive ...peptides. Milk proteins have high nutritive value and remarkable medicinal properties. They are known as potential health-promoting ingredients of functional foods, and the dairy industry has already commercialized many milk proteins and peptide-based products which can be consumed as part of a regular daily diet. Besides, cheese is highly susceptible to contamination by pathogenic and spoilage microorganisms, which results in a decrease in its shelf life and cause serious risks to the consumers’ health. Nowadays, the food industry is continuously becoming more specialized towards meeting consumer needs and demands. Consumers demand safe products, which are also preferably free of synthetic additives. Therefrom to the need to search for natural additives has emerged. Botanicals and their extracts came to an interest as a natural alternative for cheese preservation and quality enhancer. Some substances have demonstrated good effects against most pathogens of cheese such as Listeria monocytogenes, Staphylococcus aureus, and Salmonella spp. Nevertheless, it is not quite clear do the botanical addition affect cheese quality characteristics. This review aims to present the effect of added botanicals such as medicinal plants, herbs, spices and essential oils to cheeses in the function of protection against pathogens and spoilage microorganisms, as well as for their influence on the cheese quality.
The aim of this study was to determine the effect of the quantity of transglutaminase as well as conditions of its application (direct, or after activation by milk heating for 2 h at 40?C and for 1 ...min at 80?C), on yoghurt viscosity manufactured from two kinds of low fat milk (0.1 % w/w fat and 0.5% w/w fat) during 10 days of storage. The fermentation in both series started after the adequate amounts of probiotic starter culture ABT-4 (Chr. Hansen A/S Denmark) were added to the milk at 43?C. After milk fermentation at pH 4.5, probiotic yoghurt samples were cooled to 8?C, gently homogenized and packed in plastic containers and stored for 10 days, at +4oC. Viscosity of all samples was measured at 5?C on a Haake Rheostress 600 viscosimeter. On the basis of the obtained results it can be concluded that yoghurt samples produced with low level of transglutaminase activated prior to fermentation have significantly better rheological properties than the samples produced without activation and yoghurt control. Generally, the application of low level transglutaminase in low - fat yoghurt production improves overall rheological properties of the final product.
U radu je ispitan uticaj koncentracije transglutaminaze (0,02%, 0,06% i 0,12%) i tehnoloskog procesa proizvodnje (sa i bez aktivacije enzima) na viskozitet jogurta tokom skladistenja. Za proizvodnju jogurta korisceno je pasterizovano mleko sa: 0,1% i 0,5% mlecne masti. Prva grupa uzoraka jogurta je proizvedena uz dodatak transglutaminaze istovremeno sa starter kulturom, dok je za proizvodnju druge grupe uzoraka enzim transglutaminaza prethodno aktiviran 2 sata na temperaturi od 40?C, a potom je inaktivisan primenom termickog tretmana 80?C, 1 min. Fermentacija mleka je vrsena dodatkom probiotske starter kulture ABT-4 (Lactobacillus acidophilus-5, Bifidobacterium-12, S. thermophilus, Chr. Hansen A/S Denmark) na temperaturi 43?C. Nakon postizanja pH vrednosti 4,5 uzorci probiotskog jogurta su ohladjeni, homogenizovani, upakovani u plasticne case i skladisteni na temperaturi +4?C. Viskozitet uzoraka jogurta proizvedenih primenom transglutaminaze meren je viskozimetrom Haake RheoStress 600 (Karlsruhe, Nemacka) nakon proizvodnje i tokom 10 dana skladistenja. Na osnovu izvrsenih ispitivanja utvrdjeno je da uzorci jogurta proizvedeni sa dodatkom manje koncentracije transglutaminaze uz prethodnu aktivaciju enzima imaju znatno bolje reoloske karakteristike od uzoraka jogurta dobijenih bez aktivacije enzima. Generalno posmatrano najbolje reoloske osobine imaju uzorci jogurta sa 0,02% transglutaminaze, proizvedeni uz prethodnu aktivaciju enzima. Izmedju uzoraka sa 0,1% masti i 0,5% mlecne masti razlike u promeni viskoziteta tokom skladistenja su neznatne.
The aim of this work was to investigate the application of common packaging materials polypropylene (PP) and polystyrene (PS) in the probiotic fresh cheese production packaging. Probiotic and ...traditional cheeses were produced from milk with standardized milk fat content of 2.3 g/100 g including the application of two cultures (probiotic and traditional). The samples were packed in the PP and PS cups and stored at 4 ºC for 30 days. The observed permeability of gases through the two applied packaging materials was significantly different. Cheese samples were analysed for microbiological properties whereby lactic acid bacteria, Bifidobacterium sp. and aerobic mesophilic bacteria (AMB) were determined. Packaging materials showed no significant effect on the content of ascorbic acid which is known to be sensitive to the presence of oxygen.
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