Lower Syneresis Research Articles

Possibilities to develop low-fat products: a review

Abstract Research has proved a relationship between high fat consumption and rise in obesity, atherosclerosis, coronary heart diseases and high blood pressure. Therefore is recommended the moderate consumption of fat, such that the total fat does not exceed 30% of total energy intake. Our body needs fats because are providers of calories, essential fatty acids, fat-soluble vitamins and also they are necessary ingredients of the foods. The development of products with low-fat content can be considerate a challenge because the lipids offers aroma, texture, appearance, flavour and mouth feel, qualities that customers want in food products. A fat reduction can be achieved by using different fat replacers to ensure the functionality of the replaced fat. Functional components of fat replacers can have a significant role in promotion of wellbeing, in treating and preventing diseases. Thus, fat replacers should be recognized as safe and healthy, which have sensorial and functional properties. This paper reviews the fat replacers used to obtain foods as meat-based or dairy products. Some ways to obtain healthier meat products by reducing saturated fats content consist in the utilization of unsaturated vegetable oils, vegetable products, fibre. The utilization of fibre in products such bolognas, sausages or hamburgers, can improve the texture profile, binding properties and the characteristics regarding the cooking process. A fat reduction in dairy products can be achieved by replacing it with starches, polysaccharides, gums or fibres from cereal, vegetables and fruits. In acidified milk products, fibres have benefits as: low syneresis, sensory characteristics accepted by consumers, improvement of texture and rheological properties. In cheeses production, the fat reduction can be realised by replacing it with carbohydrate or protein-based replacers in order to obtain a final product with proper characteristics.

Evaluation of Various Properties of Symbiotic Yoghurt of Buffalo Milk

In present study the set-type yoghurt samples were prepared from buffalo milk, Lactobacillus acidophilus and Bifidobacterium bifidium as probiotics and lactoluse, oligofructose and inulin as prebiotics. Changes in pH value, syneresis and probiotic counts along with sensorial properties were tested in all of yoghurt samples after preparation up to 21 days at 4C. According to the results of pH test, post acidification with a range of 4.53–3.93 was observed. Using prebiotics simultaneously led to the significant lower syneresis rate during the storage. Probiotic bacteria used in this study were found to have survived above 7 log cfu/mL throughout the study period. The present study proved that prebiotics improved physicochemical properties and enhanced probiotic bacteria survival in the experimental yoghurts. On the other hand, control and probiotic yoghurts were preferred by the sensory panel over symbiotic yoghurt. Practical Applications There is a high demand for consumption of buffalo milk and its derived products worldwide. Buffalo yoghurt is a good carrier for developing symbiotic yoghurt. Probiotics just in adequate amounts can have beneficial effects for the host and therefore their viability should be monitored throughout storage time of symbiotic yoghurt, as they must survive in the gut environment. Sensory properties of yoghurt are important factors for its popularity as well. Therefore symbiotic yoghurt was made using Lactobacillus acidophilus and Bifidobacterium bifidium along with prebiotics including inulin, lactulose and oligofructose to settle the most beneficial probiotic–prebiotic combination, that have at least the minimum requirement of probiotics as well as good sensory properties for development of a marketable symbiotic yoghurt of buffalo milk.

Chemical Properties and Sensory Evaluation of Probiotic Yoghurt Manufactured with Aqueous Extract of Aloe vera

In recent years, consumer demand for a new range of dairy products, including yoghurts, which have functional and designed sensory properties have increased. In the present research physicochemical, microbiological and sensory attributes of yogurts manufactured from cow milk with aqueous extract of Aloe vera and Lactobacillus casei before and after cold storage for different periods of time (1, 3, 5, 7 and 10 days) were investigated. Titrable acidity (TA) of examined yoghurts during storage period at 4°C increased and their pH decreased significantly (P<0.05). The percentages of Water Holding Capacity (WHC) and Syneresis of yoghurt samples through the 10 days storage period were significantly decreased and increased, respectively (P<0.05). Viability of L. casei was significantly higher in probiotic yoghurt samples than others with Aloe vera extract after the end storage time. Sensory evaluation of examined yoghurts showed that Aloe vera extract had no effect on sensory quality of probiotic yoghurt samples. It was concluded that probiotic yoghurt with 2.5% Aloe vera extract with low syneresis and high WHC had better physicochemical, microbiological and sensory properties in comparison with the other probiotic yoghurt samples.

Influence of milk protein cross-linking by transglutaminase on the rennet coagulation time and the gel properties.

Transglutaminase (TGase) modifies milk proteins by cross-linking of caseins, with increased cheese yield being the main technological benefit. In the present work the influence of TGase addition in different concentrations (0, 1, 2 and 3 U g(-1) protein in the system) and under different incubation conditions (0 h, 40 °C/2 h, 25 °C/4 h and 5 °C/16 h) on the rennet coagulation time (RCT) and the comprehensive rennet gel properties were investigated. Modification of milk proteins by TGase in a concentration-dependent manner caused longer RCT and lower gel firmness. The highest TGase concentration and incubation at 40 °C for 2 h resulted in the longest RCT and the lowest gel firmness. Rennet gels obtained from TGase modified milk were characterised by significantly lower values of texture parameters, lower syneresis and were composed of smaller casein micelles, thinner chains and smaller clusters than those obtained from the control milk. The content of whey proteins in the gel from modified milk was higher and the content of individual casein fractions in the milk samples and rennet gels decreased upon TGase modification. Rennet cheese with modified textural and nutritional properties and improved yield can be obtained upon TGase modification but simultaneous addition of rennet and TGase is recommended. © 2015 Society of Chemical Industry.

Influence of blanching and drying methods on molecular structure and functional properties of elephant foot yam (Amorphophallus paeoniifolius) flour

Abstract The purpose of the present study was to investigate the effect of solar and freeze drying approaches on the physico-chemical, thermal and pasting properties of raw and blanched elephant foot yam (Amorphophallus paeoniifolius). Morphologically, starch granules in blanched and solar dried flours were observed as heterogeneous and collapsed while raw freeze dried flour was the least affected. The amylose content was highest in IDSB (29.50%) followed by DSB, FDB, FDR, and IDSR while lowest in DSR (15.83%). Freeze dried flours had higher whiteness (L*) than solar dried flours. Freeze dried raw flour (19.38%) had the highest solubility while freeze dried blanched flour (8.39%) exhibited the lowest. Freeze dried flour samples had the least swelling power. Direct solar dried (raw and blanched) flours showed relatively lower syneresis than freeze dried flours. The differences in pasting profile, textural analysis and relative crystallinity could be explained as a function of variation in amylose content and the drying method employed. The solar dried flours had higher T0, TP, and TC than the freeze dried flours (raw and blanched). The ΔH gel value of flours was highest for freeze dried raw flour and lowest for direct solar dried blanched flour.

A new milk-clotting enzyme produced by Bacillus sp. P45 applied in cream cheese development

The growing demand for natural coagulants led to an increased necessity for rennet substitutes, promoting a search for new sources of proteases with coagulant properties. The aim of this study was to investigate the application of a bacterial enzyme as a novel milk-clotting protease in the development of cream cheese enriched with chia and quinoa flour. At the concentration of 30 mg/mL, the milk-clotting strength was similar to that observed for commercial chymosin, demonstrating the enzyme ability to catalyze the hydrolysis of milk casein. The cheese developed showed high water retention (≥99.0%) and consequently low syneresis process. The results indicate that the product made using the enzyme showed adequate sanitary conditions and technological characteristics indicated that the product is highly stable and viable.

Characterization of curdlan produced by Agrobacterium sp. IFO 13140 cells immobilized in a loofa sponge matrix, and application of this biopolymer in the development of functional yogurt.

Agrobacterium sp. IFO 13140 cells were immobilized on a loofa sponge and used to produce curdlan over five successive cycles. The interaction between microbial cells and the loofa sponge as well as the produced curdlan were characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectrometry. The purity of the curdlan was also evaluated. The storage stability of the immobilized cells was assessed and the produced curdlan was used in a functional yogurt formulation. The average curdlan production by immobilized cells was 17.84 g L(-1) . The presence of the microorganism in the sponge was confirmed and did not cause alterations in the matrix, and the chemical structure of the curdlan was the same as that of commercial curdlan. The purity of both was similar. The immobilized cells remained active after 300 days of storage at -18 °C. The use of the produced curdlan in a functional yogurt resulted in a product with lower syneresis. A large number of cells physically adhered to the surface of loofa sponge fibers, and its use as an immobilization matrix to produce curdlan was effective. The use of the produced curdlan in yogurt allowed the development of a more stable product. © 2015 Society of Chemical Industry.

Microbiological, functional and rheological properties of low fat yogurt supplemented with Pleurotus ostreatus aqueous extract

Pleurotus ostreatus aqueous extract was incorporated to milk aiming to produce a yogurt with different functional and rheological characteristics. Viable counts of Streptococcus thermophilus and Lactobacillus bulgaricus, pH, lactic acid production, changes in rheological and structural properties (syneresis, texture profile analyses, color and microstructure), antioxidant capacity and total phenolic were followed throughout 28 days of cold storage. Addition of POE increased S. thermophilus and L. bulgaricus CFU counts. Low fat yogurts with POE exhibited lower syneresis and firmness, but more adhesiveness, springiness and cohesiveness than control. Supplemented yogurts were darker, contained more polyphenols and exhibited higher antioxidant activity than controls in cold storage. Overall, the results indicated that POE can be used to manufacture low fat yogurt with functional activity and at the same time modifies rheological properties.

EFFECTS OF ARTICHOKE (CYNARA SCOLYMUS L.) EXTRACT ADDITION ON MICROBIOLOGICAL AND PHYSICO-CHEMICAL PROPERTIES OF PROBIOTIC YOGURT

In this study, the effects of addition of artichoke (Cynara scolymus L.) leaf extract into yogurt (0 or 0.5%) on biochemical parameters (pH, titrable acidity) and the viability of probiotic bacteria (Lactobacillus acidophilus LA-5, Bifidobacterium lactis BB-12) during fermentation and over 28 days of refrigerated storage (4°C) were investigated. Moreover, the amounts of syneresis, total phenolic content, antioxidant activity and sensory attributes of yogurts at the end of fermentation were assessed. Yogurts contained the two yogurt bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus: ABY) or only S. thermophilus (ABT) as adjunct culture to probiotics. Yogurts containing Cynara scolymus L. (ABT-C and ABY-C) had faster acidity increase, shorter incubation time and greater final titrable acidity than control yogurts (ABT and ABY). Also, yogurts containing Cynara scolymus L. had lower syneresis, higher total phenolic content and greater antioxidant activity. ABT-C yogurt had the ever greatest viability of probiotics. In case of samples sensory evaluation, generally, the highest total score was related to ABT yogurt whereas lowest total score belonged to ABT-C yogurt.

Physico-chemical and gel properties of agar from Gracilaria tenuistipitata from the lake of Songkhla, Thailand

Physico-chemical and gelling properties of agar extracted from Gracilaria tenuistipitata as affected by alkaline pretreatments using NaOH and KOH at various levels (3–7%, w/v) were investigated. Yield of native agar was 17.1%, whilst those of agars pretreated with NaOH and KOH ranged from 23.6% to 26.1%. Agar with alkaline pretreatment generally showed the better gelling property as evidenced by higher gel strength, gelling, melting temperatures and viscosity with coincidentally increased 3,6-anhydrogalactose (3,6-AG) content than did native agar. Additionally, native agar had a higher sulphate content with lower syneresis (P < 0.05) than those with alkaline pretreatment. Regardless of alkaline concentration, NaOH used for pretreatment rendered agar with a higher quality, compared with KOH. Agar (1.5%, w/v) pretreated with 5% NaOH exhibited the highest gel strength (482 g/cm2) with high yield (25.3%). The decrease in total sulphate content and the increase in 3,6-AG content were observed in agar having 5% NaOH pretreatment as determined by FTIR spectroscopy. Finer and more compact network with smaller pores was visualised in gel from agar with 5% NaOH pretreatment. Therefore, the appropriate pretreatment by using 5% NaOH could increase yield and improve the gelling property of agar from G. tenuistipitata harvested from the lake of Songkhla, Thailand.

Approaches to minimise yoghurt syneresis in simulated tzatziki sauce preparation

The phenomenon of syneresis becomes more profound in increased moisture yoghurt‐based products. Such a product is the traditional Greek appetizer tzatziki that contains cucumber, a vegetable with a high moisture content. During the manufacture of tzatziki, the addition of cucumber causes the protein network to break up, provoking an increase in syneresis. The aim of this study was to investigate a tzatziki manufacturing procedure that will lead to significantly decreased syneresis. Two different manufacturing procedures were compared: the extra moisture coming from cucumber was introduced before or after fermentation. The effect of adding whey protein concentrate (WPC), albumin, sodium caseinate or a mixture of these was also studied. The results show that the addition of extra moisture before yoghurt fermentation leads to a significantly lower syneresis (7.5%) and higher consistency (2000 cp) than those obtained in the case of addition after fermentation (25% and 1500 cp, respectively). The use of albumin, WPC or a mixture of albumin, WPC and sodium caseinate further decreased the phenomenon of syneresis to below 5%, without altering the colour of the product (ΔΕ* &lt; 2.3).

Effects of granule size of cross-linked and hydroxypropylated sweet potato starches on their physicochemical properties.

Sweet potato starch was modified by cross-linking, hydroxypropylation, and combined cross-linking and hydroxypropylation, and the starches were subsequently sieved to obtain differently sized granule fractions. The effects of granule size of native and modified sweet potato starch fractions and all fractions were investigated with respect to their physicochemical properties. The large-size granule fraction (27-30 μm) showed a 16-20% higher chemical phosphorylation and a 4-7% higher hydroxypropylation than the small-size granule fraction (14-16 μm). The large-size granule fractions of native and modified sweet potato starches showed lower transition temperatures (0.7-3.1 °C for peak temperature of gelatinization) and lower enthalpy changes (0.6-1.9 J/g) during gelatinization than the small-size granule fractions, making the sweet potato starch different from cereal starches. The large-size granule fraction of native starch showed a higher paste viscosity (78-244 cP) than the corresponding small-size granule fraction. In addition, cross-linking and hydroxypropylation affected the paste viscosity of the large-size granule fraction significantly more than that of the small-size granule fraction when compared to the corresponding parental starch fractions. The large-size granule fraction of native and dual-modified starches showed a lower syneresis after freeze-thaw treatments than the small-size granule fractions. The difference in swelling power between large- and small-size granule fractions was not significant. In general, the large-size granule fraction of sweet potato starch was more susceptible for cross-linking and hydroxypropylation and the physicochemical properties were changed to a higher extent compared to the corresponding small-size granule fraction.

Physiochemical properties, microstructure, and probiotic survivability of nonfat goats' milk yogurt using heat-treated whey protein concentrate as fat replacer.

There is a market demand for nonfat fermented goats' milk products. A nonfat goats' milk yogurt containing probiotics (Lactobacillus acidophilus, and Bifidobacterium spp.) was developed using heat-treated whey protein concentrate (HWPC) as a fat replacer and pectin as a thickening agent. Yogurts containing untreated whey protein concentrate (WPC) and pectin, and the one with only pectin were also prepared. Skim cows' milk yogurt with pectin was also made as a control. The yogurts were analyzed for chemical composition, water holding capacity (syneresis), microstructure, changes in pH and viscosity, mold, yeast and coliform counts, and probiotic survivability during storage at 4 °C for 10 wk. The results showed that the nonfat goats' milk yogurt made with 1.2% HWPC (WPC solution heated at 85 °C for 30 min at pH 8.5) and 0.35% pectin had significantly higher viscosity (P < 0.01) than any of the other yogurts and lower syneresis than the goats' yogurt with only pectin (P < 0.01). Viscosity and pH of all the yogurt samples did not change much throughout storage. Bifidobacterium spp. remained stable and was above 10(6) CFU g(-1) during the 10-wk storage. However, the population of Lactobacillus acidophilus dropped to below 10(6) CFU g(-1) after 2 wk of storage. Microstructure analysis of the nonfat goats' milk yogurt by scanning electron microscopy revealed that HWPC interacted with casein micelles to form a relatively compact network in the yogurt gel. The results indicated that HWPC could be used as a fat replacer for improving the consistency of nonfat goats' milk yogurt and other similar products.

Production of a transglutaminase from Zea mays in Escherichia coli and its impact on yoghurt properties

A gene from Zea mays coding a TGase was expressed in E. coli and identified by Western blotting. Under optimal expression conditions, the production and specific activity of refolded TGZ were 1.41 mg/L and 0.34 U/mg. The activated TGZ was employed to cross‐link milk proteins. The yoghurt treated with TGZ showed a lower syneresis, higher apparent viscosity and texture than untreated yoghurt. The properties of TGZ‐treated sample were better than those of MTG‐treated samples, so TGZ may have potential as an additive in yoghurt manufacture.

Effects of various whey proteins on the physicochemical and textural properties of set type nonfat yoghurt

In this study, the changes during storage in the physicochemical, textural and sensory properties of nonfat yoghurts fortified with whey proteins, namely whey protein concentrates (WPC), whey protein isolates and whey protein hydrolysates, were investigated. Enrichment of nonfat yoghurt with the whey protein additives (1% w/v) had a noticeable effect on pH, titratable acidity, syneresis, water‐holding capacity, protein contents and colour values on the 14th day of storage (P &lt; 0.01). The addition of whey proteins to the yoghurt milk led to increases in the hardness, cohesiveness and elasticity values, resulting in improved textural properties. The addition of WPC improved the texture of set‐type nonfat yoghurt with greater sizes in the gel network as well as lower syneresis and higher water holding capacity. This study suggests that the addition of whey protein additives used for fortification of yoghurt gave the best textural and sensory properties that were maintained constant during the shelf life.

Amylose–Potassium Oleate Inclusion Complex in Plain Set‐Style Yogurt

Health and wellness aspirations of U.S. consumers continue to drive the demand for lower fat from inherently beneficial foods such as yogurt. Removing fat from yogurt negatively affects the gel strength, texture, syneresis, and storage of yogurt. Amylose-potassium oleate inclusion complexes (AIC) were used to replace skim milk solids to improve the quality of nonfat yogurt. The effect of AIC on fermentation of yogurt mix and strength of yogurt gel was studied and compared to full-fat samples. Texture, storage modulus, and syneresis of yogurt were observed over 4 weeks of storage at 4 °C. Yogurt mixes having the skim milk solids partially replaced by AIC fermented at a similar rate as yogurt samples with no milk solids replaced and full-fat milk. Initial viscosity was higher for yogurt mixes with AIC. The presence of 3% AIC strengthened the yogurt gel as indicated by texture and rheology measurements. Yogurt samples with 3% AIC maintained the gel strength during storage and resulted in low syneresis after storage for 4 wk.

Quality attributes of the set-style yoghurt from whole bovine milk as affected by an enzymatic oxidative cross-linking

The impact of an enzymatic oxidative cross-linking of milk proteins on quality attributes of set-style yoghurt was investigated in the present study. Whole bovine milk was pretreated by a ternary system comprising horseradish peroxidase, glucose oxidase and glucose at 4°C for 48 h and fermented by a commercial direct vat set starter after table sugar addition and pasteurization. The measured bacterial count in the treated milk was less than 2 × 103 CFU/mL. Electrophoresis results revealed that both the treated milk and the treated yoghurt contained protein polymers about 11%. The treated yoghurt had the same main composition as the control yoghurt, but higher apparent viscosity, elastic and viscous moduli, larger thixotropic loops area (3.19 vs. 1.97 Unit) and lower syneresis (21.0% vs. 33.8%). Texture profile and microstructure analysis showed that the treated yoghurt had higher hardness (106.6 vs. 92.0 g) or adhesiveness (450 vs. 367 g s), and finer network structure.

Microstructure and stability of skim milk acid gels containing an anionic bacterial exopolysaccharide and commercial polysaccharides

The structure and stability of acid milk gels containing an anionic exopolysaccharide (EPS) produced by Lactobacillus rhamnosus RW-9595M in combination with different commercial polysaccharides were studied. Gel internal structure was visualised using confocal scanning laser microscopy; protein, EPS and polysaccharides were labelled using different fluorophores to resolve their specific location. EPS at 0.01% resulted in lower syneresis (2.5%) than control (3.7%); micrographs showed EPS co-localised with protein and reinforcing network connectivity. However, 0.05% EPS increased syneresis to over 17%, although no significant changes in gel strength were detected. Pectin or agar–agar alone at 0.05% resulted in very low syneresis (<1.8%). Both polysaccharides were found to form a tenuous secondary yet more ramified network, effectively reducing pore size. Mixing pectin or agar–agar with EPS at 0.05% resulted in a loss of their functionality. Anionic polysaccharides with stiff molecular structures, such as xanthan or κ-carrageenan, induced extensive protein self-aggregation and syneresis.

Effects of improved post-harvest handling on the chemical constituents and quality of carrageenan in red alga, Kappaphycus alvarezii Doty

Red alga Kappaphycus alvarezii Doty is an important commercial species widely cultivated in southeast Asian countries for its polysaccharide, kappa-carrageenan. Common post-harvest handling technique involves sun-drying of harvested seaweed on platforms at the farms. Quantity and quality of carrageenan varies depending on the duration and care taken during the post-harvest handling of the raw seaweed. In this study, dynamics of moisture content, water activity index (aw), carrageenan yield, and carrageenan quality were investigated by subjecting the seaweed to three post-harvest methods: (1) freeze-drying (FD), (2) shade-drying (SD), and (3) direct sun-drying (DSD). Seaweed dried under FD and SD produced high yield (56–58 %), superior gel strength (1,454–1,424 g cm−2), high viscosity (57–58 cPs), and low syneresis (15–17 %). But, carrageenan extracted from DSD seaweed gave 28 % lower yield, 38 % lower gel strength, 27 % lower viscosity, and 8–9 % higher syneresis. In addition, gelling temperature and melting temperature of the DSD carrageenan were lower by 4 and 9 °C, respectively. Molecular size analyses of carrageenan extracted from seaweed dried under FD and SD contained carrageenan of 700 KDa (80 %) and 200 KDa (4–10 %). However, carrageenan extracted from DSD seaweed contained smaller carrageenan molecules, 460 KDa (55 %), 210 KDa (25 %), and <100 KDa (20 %). Further, scanning electron microscope images illustrated the severe effects of DSD on the morphology of seaweed cells. Therefore, SD technique was found to be the best post-harvest processing technique that gave quality carrageenan in a high quantity. Due to its simplicity and low cost, it is a practical approach to be practiced in southeast Asian countries.

Improvement on the freeze–thaw stability of corn starch gel by the polysaccharide from leaves of Corchorus olitorius L.

Effect of the polysaccharide from leaves of Corchorus olitorius L. (PLC) on the freeze–thaw (FT) stability of corn starch gel was studied. PLC was incorporated into the starch gel at 0.7% and total solid was adjusted to 6.0%. The syneresis was measured by the centrifugal-filtration method and, as a result, addition of PLC reduced effectively the syneresis of the starch gel even after 5 FT cycles, which was less than one third that of the normal starch gel. The rheological changes of the starch/PLC gel during the FT treatments were evaluated while the gel remained on the rheometer plate. The starch/PLC gel had less significant changes in the rheological parameters during the FT cycles than starch/guar gum or xanthan gum gel systems. SEM images showed that PLC stabilized the gel matrix surrounding pores, which would contribute to both a lower syneresis production and a higher stability in the rheological behavior at FT.