Addition of pectin and whey protein concentrate minimises the generation of acid whey in Greek-style yogurt

Effects of hydrocolloids and oleogel on techno-functional properties of dairy foods

This paper aims to overview the influence of different gels that including hydrocolloids and oleogel on techno-functional changes of dairy foods. The hydrocolloids are widely added to dairy products as stabilizers, emulsifiers, and gelling agents to enhance their texture, or improve sensory properties to meet consumer needs; and the newly developed oleogel, which despite less discussed in dairy foods, this article lists its application in different dairy products. The properties of different hydrocolloids were explained in detail, meanwhile, some common hydrocolloids such as pectin, sodium alginate, carrageenan along with the interaction between gel and proteins on techno-functional properties of dairy products were mainly discussed. What's more, the composition of oleogel and its influence on dairy foods were briefly summarized. The key issues have been revealed that the use of both hydrocolloids and oleogel has great potential to be the future trend to improve the quality of dairy foods effectively.

Effect of Milk Origin and Seasonality of Yogurt Acid Whey on Antioxidant Activity before and after In Vitro Gastrointestinal Digestion

Yogurt acid whey (YAW) is a by-product of Greek strained yogurt production. The disposal of YAW constitutes an environmental problem, and given the increasing demand of Greek yogurt worldwide, its handling is a challenge. However, whey-derived peptides, resulting from microbial fermentation as well as those resulting from further hydrolysis during the digestion process, have been linked to enhanced biological activities. In this study, the antioxidant capacity of 33 samples of YAW obtained from Greek dairy companies of bovine, ovine or caprine origin was investigated using both cell-free and cell-based assays. The YAW samples, their in vitro digestion products (YAW-Ds) and a fraction of the digests (less than 3 kDa; YAW-D-P3) were assessed using four biochemical assays, namely ORAC, ABTS, FRAP and P-FRAP. Our data revealed a higher antioxidant capacity for digested samples compared with undigested samples, with all four methods. ORAC values after in vitro digestion were higher for the ovine samples compared to their bovine (YAW-D and YAW-D-P3) and caprine (YAW-D-P3) counterparts. Furthermore, the YAW-D-P3 fraction derived from samples collected in the summer months exhibited higher ORAC values when compared to the respective fraction from the winter months' samples. The cellular antioxidant activity of ovine YAW-D-P3 was improved in H2O2-treated HT29 cells compared to the control H2O2-treated cells. However, YAW-D-P3 could not trigger either the pathways involving the transcription factors NF-κB or NFE2L2 or the gene expression of SOD1, CAT and HMOX1 in LPS-challenged THP-1-derived macrophages. These results suggest that YAW, and particularly YAW from ovine origin, could be used as a natural source for its antioxidant potential in human and animal nutrition.

Whey proteins as a functional food: Health effects, functional properties, and applications in food

Functional foods are defined as foods and ingredients that exhibit health benefits beyond their nutritional value. Research on functional foods is increasing rapidly as they may help prevent and manage some non-communicable diseases. Whey proteins are recognized as a high-quality nutrient source and known to contain some bioactive components. They are rich in essential amino acids such as cysteine, branched-chain amino acids such as leucine, valine, and isoleucine, and bioactive peptides. Whey proteins look promising as a potential functional food, given its antioxidant, anti-inflammatory, blood pressure lowering, anti-obesity, and appetite suppressing effects that is discussed in the literature. Whey proteins also show functional properties that play an essential role in food processing as an emulsifier, fat-replacer, gelling and encapsulating agent and are known to improve sensory and textural characteristics of food. This review focuses on the functional food aspects of whey proteins, associated health effects, and current food applications.

Antioxidant pectins from eggplant (Solanum melongena) fruit exocarp, calyx and flesh isolated through high-power ultrasound and sodium carbonate

Dried and milled eggplant fruit peel and calyces (PC) and mesocarp, placenta and core (Mes) were utilized as natural sources of valuable chemicals. Pectins were extracted with 0.1 M Na₂CO₃ (1 h; 23 °C). A high-power ultrasound (US) pretreatment (10 min net time; 12.76 W/cm² power intensity) in 10:200 (g/mL) powder:water ratio led to the lowest solvent and energy consumptions after the subsequent 0.1 M Na₂CO₃ stirring, permitting the highest recoveries of uronic acid (UA) from PC and Mes (80.25 and 93.8 %, respectively). Homogalacturonans (>65 % w/w UA) of low degree of methylesterification, of acetylation, and 90,214-138,184 Da molecular weights with low polydispersity (≈1.32-1.40) were obtained. They included released ferulate (≈3.5 mg/100 g) esterified pectins. Antioxidants (caffeoylquinic acid, putrescine and spermidine derivatives, β-carotene, lutein) gave additional technological value to their thickening effect as pectins protected tryptophan, tyrosine, alkyl side chains and sulfhydryl of skim milk proteins from UV-C photo-oxidation.

Effect of adding high concentrations of retrograded starch with different amylose content on the physicochemical properties and sensory attributes of Greek-style yogurt

It is well known that using retrograded starches confers many technological advantages, as well as health benefits when consumed in adequate doses; however, these properties are closely related to the type of starch and/or the treatment applied, therefore, it is of interest to add retrograded starch to popular products such as Greek yogurt. The aim of this work was to investigate the effect of adding two types of retrograded corn starch with different amylose content to a non-strained type of Greek-style yogurt. Retrograded starch from starch containing 27 % (RNS) or 70 % (RHS) amylose was added to yogurt at 0, 10, 12.5, or 15 g/100 g before storage at 4 °C for 14 d. The resistant starch (RS) content, pH, syneresis, flow behavior index, and consistency index, were measured every week. A sensory test was carried out in yogurt added with 12.5 g/100 g of retrograded starches to evaluate acceptability. Adding retrograded starch significantly reduced syneresis while increasing the consistency, firmness, and resistant starch content of the yogurt. No significant differences in general acceptance were observed in samples added with RNS when compared to control. Although a significant difference was observed after adding RHS, the acceptance of the product is still convenient. Adding a high concentration of retrograded starch could help to ensure doses enough for a prebiotic effect of RS with concentrations of 1.74 ± 0.37 to 2.32 ± 0.09 g/100 g and from 3.5 ± 0.08 to 4.21 ± 0.08 g/100 g when RNS or RHS is added while maintaining the quality characteristics of Greek-style yogurt during storage without compromising the acceptability.

Effect of Modified Manufacturing Conditions on the Composition of Greek Strained Yogurt and the Quantity and Composition of Generated Acid Whey

Greek strained yogurt is produced in high quantities worldwide. This production leaves behind acid whey, a by-product that is an environmental challenge. Hence, efforts are made to minimize the acid whey generation. In this study, the combined effect of the different heat treatment levels of milk and the different time of straining on the composition of the produced strained yogurt, as well as on the quantity and composition of the expelled acid whey, was investigated. The initial yogurts were prepared with bovine milk heated at 85 °C/16 s or 100 °C/16 s or 90 °C/5 min, and the acid whey was removed by centrifugation (5500 rpm, 5 min, 25 °C) either immediately after incubation or after 24 h. The results showed that, regardless of the heat treatment of milk, straining after 24 h resulted in an 8% increase in the yield in strained yogurt and about an 11% decrease in the generated acid whey, compared to straining immediately after incubation. The heat treatment level of milk significantly influenced the fat, lactose, and total solids contents of the strained yogurts, as well as the residual whey proteins, protein, and total solids contents of acid whey. Yogurt's sensory properties were not affected significantly. It was concluded that the quantity of the acid whey expelled during the production of Greek strained yogurt could be decreased without affecting the general quality of the yogurt.

A review of factors influencing the quality and sensory evaluation techniques applied to Greek yogurt

Greek yogurt is one of the fastest growing products in the dairy industry. It is also known as strained yogurt, which is obtained after draining the whey. As a result of the draining process, Greek yogurt has higher total solids and lower lactose than regular yogurt. Since it is a concentrated yogurt, its sensory characteristics are different from regular yogurt. However, there is little information about factors influencing the quality of Greek yogurt and sensory evaluation techniques applied to Greek yogurt. This review aims to describe the effects of ingredients, starter cultures, processing techniques and other parameters on quality characteristics and sensory properties of Greek yogurt. In addition, advantages and limitations of novel sensory evaluation techniques applied to Greek yogurt products are discussed. In particular, we take a look at advanced techniques such as the electronic nose and electronic tongue and the benefits of these techniques with regard to Greek yogurt. This review should help the Greek yogurt industry to improve its current products and develop innovative products based on appropriate food evaluation techniques.

Clean Label Trade-Offs: A Case Study of Plain Yogurt

Consumer demand for clean label has risen in recent years. However, clean label foods with simple and minimalistic ingredient lists are often expensive to produce and/or may possess less desirable sensory qualities. Accordingly, understanding consumer preferences regarding the clean label trend would be of great interest to the food industry. Here we investigate how ingredient lists and associated sensory quality descriptions may influence consumer preferences using a hypothetical choice experiment. In particular, we test the impacts of four common stabilizers (carrageenan, corn starch, milk protein concentrate, and pectin) and textural characteristics on preferences and willingness to pay for plain yogurt. A total of 250 yogurt consumers participated in the study. The results of a mixed logit analysis suggest that clean labeling significantly increases the likelihood of consumer choice, while poor texture reduces consumer choice. More importantly, the negative impact of poor texture seems to be less significant for clean label yogurts compared to that for yogurts with longer ingredient lists. Among all stabilizers, corn starch in particular has a significant negative impact on consumer choice. The estimated average consumer willingness to pay for clean labels is between $2.54 and $3.53 for 32 oz yogurt formulations. Furthermore, clean labels minimize the negative impact of textural defects with consumers willing to pay an estimated premium of $1.61 for the family size yogurt with a simple ingredient list. Results of latent class modeling reveal two classes of consumers with similar patterns of demand who prefer clean labels and, on average, would rather purchase a yogurt with a textural defect than opt out of purchasing a yogurt entirely. Implications for the food industry are discussed.

Probiotic Greek yogurt: effect of the addition of prebiotic fat substitutes on the physicochemical characteristics, probiotic survival, and sensory acceptance

In this research communication we evaluate the impact of the addition of prebiotic components (inulin, polydextrose, and modified starch, 40 g/l) as fat substitutes on the physicochemical characteristics, probiotic survival, and sensory acceptance of probiotic (Lacticaseibacillus casei 01, 108 CFU/ml) Greek yogurts during storage (7 °C, 28 d). All formulations had probiotic counts higher than 107 CFU/ml during storage and simulated gastrointestinal conditions (SGIC). The prebiotic components increased the probiotic survival to the enteric phase of the SGIC, with inulin producing the most pronounced effect. Inulin addition resulted in products with lower pH values and consistency and higher titratable acidity during storage, with negative impact on the sensory acceptance (flavor, texture, and overall impression) at the end of the storage period. Modified starch addition impacted negatively on the acceptance of the products (appearance, flavor, texture, and overall impression). Polydextrose addition resulted in products with lower consistency, but similar sensory acceptance to the full-fat yogurt. It can be concluded that it is possible to prepare potentially synbiotic Greek yogurts by desorption technique using L. casei as probiotic culture and inulin, polydextrose or modified starch as prebiotic components, with the utilization of polydextrose being advisable.

Encapsulation of tartary buckwheat flavonoids and application to yoghurt

Aims: The present work investigates the effect of tartary buckwheat flavonoid (TBF) capsules on the physical and chemical properties of yoghurt using polymeric whey protein (PWP) as a wall material.Methods: PWP was prepared by thermal polymerisation. TBF was encapsulated using PWP as the wall material via the pore-coagulation bath method. The physicochemical properties of the TBF capsules, such as the entrapment yield, moisture, average particle size, particle size distribution, surface morphology, molecular interactions, and thermal stability were investigated, in addition to the release of TBF in simulated gastric and intestinal juices. Yoghurt formulation was carried out using encapsulated TBF (3%, w/w), blank PWP beads (2.7%, w/w), and unencapsulated TBF (0.3%, w/w). A control yoghurt sample was prepared without these ingredients. The effects of encapsulated TBF on the chemical composition, acidity, texture, synaeresis, sensory properties, number of Streptococcus thermophilus and Lactobacillus, and other physical and chemical properties of the yoghurt were investigated.Results: TBF capsules were found to be sphere-shaped with porous surfaces, an average particle size of 1728.67 μm, an encapsulation yield of 92.85 ± 1.98% (w/w), and a glass transition temperature of 152.06 °C. When the TBF capsules were exposed to simulated gastric fluid for 4 h, the TBF release rate was 15.75% (w/w), while in simulated intestinal fluid, the TBF release rate reached 65.99% (w/w) after 1 h. After 5-6 h in simulated intestinal fluid, the TBF release rate reached 100% (w/w). The protein content of the yoghurt with encapsulated TBF was 3.57 ± 0.26% (w/w, p < 0.01), and the numbers of Lactobacillus and Streptococcus thermophilus were 2.45 ± 0.98 × 10⁸ (p < 0.01) and 5.43 ± 2.24 × 10⁷ CFU/mL (p < 0.05), respectively, with strong water retention being detected (p < 0.01). Samples containing the encapsulated TBF exhibited a significantly higher acceptability than the unencapsulated TBF (p < 0.01).Conclusions: Encapsulation using PWP effectively delivers TBF to the small intestine through the stomach. It also masks the bitter taste, enhances the colour of TBF-containing yoghurt, and improves the physical and chemical properties of the yoghurt.

Impact of Different Gums on Textural and Microbial Properties of Goat Milk Yogurts during Refrigerated Storage

In this study, the impact of seven different gums on textural and microbiological properties of goat milk yogurt during refrigerated storage was investigated. The results showed that yogurt containing xanthan and locust bean gums had enhanced firmness, consistency, cohesiveness, and viscosity during four weeks of storage compared to the control and yogurt fortified with other gums (p < 0.05). The addition of gums also helped to maintain the microbial viability of the yogurt culture and the probiotic Bifidobacterium spp. This study thus demonstrated that these gums could be used in the production of goat milk yogurt with enhanced textural properties.