Effect of Two Combined Functional Additives on Yoghurt Properties

Studying the Stability of Anthocyanin Pigments Isolated from Juices of Colored-Fleshed Potatoes

The aim of this study was to obtain extracts of anthocyanin pigments from red and purple-fleshed potato juices characterized by stable color. For this purpose, potato juices were pasteurized at different temperatures or fruit and vegetable concentrates were added to them. Color stability tests of the obtained pigments were carried out in model pH and temperature conditions and after adding to natural yogurt. Both the pasteurization process and the addition of fruit and vegetable concentrates to the potato juices positively affected their color and its stability in time. However, the pasteurization of the potato juices had a negative effect on the content of biologically active compounds, in contrast to the juices stabilized with the addition of fruit and vegetable concentrates. Anthocyanin pigments from red-fleshed potato juices were more stable than those isolated from the purple-fleshed potato juices. The results of model tests of the anthocyanin pigment concentrates from the colored-flesh potatoes and natural yoghurts with their addition confirmed the high stability of the tested concentrates.

Influence of Bilberry Pomace Powder Addition on the Physicochemical, Functional, Rheological, and Sensory Properties of Stirred Yogurt

Fruit processing by-products could represent a sustainable ingredient for developing innovative dairy products. The present study was conducted to develop a novel functional yogurt by adding bilberry pomace powder (BPP) at 0.5%, 1.0%, and 1.5% (w/w) levels in stirred-type yogurt production to confer color and to increase the dietary fiber and polyphenol content. Physicochemical properties of the yogurt samples, including color parameters, titratable acidity, pH, water holding capacity (WHC), and syneresis, as well as textural and rheological properties, were evaluated in yogurts on the 1, 14, and 28 days of refrigerated storage (4 °C). In addition, total phenolic content, total anthocyanin content, and radical scavenging activity were determined in yogurts, and sensory analysis was conducted. The results showed that BPP is a valuable source of polyphenols, dietary fiber, and oils rich in n-3 polyunsaturated fatty acids (n-3 PUFAs, n-6/n-3 ratio = 0.91). The incorporation of BPP imparted an attractive purple color to the yogurts, increased WHC, and reduced syneresis. Moreover, the addition of BPP improved the rheological properties, demonstrating that a more dense and stable yogurt gel network structure was obtained than the control. The yogurt enriched with 1.0% BPP received the highest scores for color, consistency, taste, and overall acceptability. Hence, bilberry pomace powder might be used as an ingredient to improve the nutritional and functional value of yogurts.

Effects and improvement mechanisms of ultrasonic pretreatment on the quality of fermented skim milk

Fermented skim milk is an ideal food for consumers such as diabetic and obese patients, but its low-fat content affects its texture and viscosity. In this study, we developed an effective pretreatment method for fermented skim milk using low-frequency ultrasound (US), and investigated the molecular mechanism of the corresponding quality improvement. The skim milk samples were treated by optimal ultrasonication conditions (336 W power for 7 min at 3 °C), which improved the viscosity, water-holding capacity, sensory attributes, texture, and microstructure of fermented skim milk (P < 0.05). Further mechanistic analyses revealed that the US treatment enhanced the exposure of fluorescent amino acids within proteins, facilitating the cross-linking between casein and whey. The increased surface hydrophobicity of fermented milk indicates that the US treatment led to the exposure of hydrophobic amino acid residues inside proteins, contributing to the formation of a denser gel network; the average particle size of milk protein was reduced from 24.85 to 18.06 µm, which also contributed to the development of a softer curd texture. This work is the first attempt to explain the effect of a low-frequency ultrasound treatment on the quality of fermented skim milk and discuss the molecular mechanism of its improvement.

Quality Assessment of Greek-Style Set Yoghurt Fortified with Extracted and Dried Australian Native Fruit, Illawarra Plum

The Illawarra plum (IP) is native to Australia and has been used as a bush food for centuries. With rich phytochemicals and natural pigments, IP has the potential to be an added ingredient to improve the physicochemical properties of food, including yoghurt. This study prepared dried IP powders through vacuum drying (VD) and freeze drying (FD), produced extracts from these dried powders, and fortified them into Greek-style set yoghurt. The changes in colour, pH, titratable acidity (TA), syneresis, total soluble solids (TS), and phytochemicals were measured throughout a chilled storage period of 28 days. The results showed that FD and FD extract could provide a stable, distinct pink colour to yoghurt. IP powders and their extracts improved TS content and, thus, the consistency of yoghurt. Compared to the control, VD, FD, and FD extract of IP did not significantly affect the level of acidity or syneresis after 28 days of chilled storage. Yoghurt fortified with FD and FD extract had the greatest level of phenolics, anthocyanins, and radical scavenging antioxidant activities. This study revealed that IP powders and their extracts can positively improve the physicochemical properties of Greek-style set yoghurt. FD powder is recommended over its extract to fortify this yoghurt, as it can be cost-effectively prepared by freeze drying and then grinding the fresh fruit into powder. Future studies are needed to evaluate other variables in yoghurt preparation, including the concentration of IP and strains of yoghurt culture. Further, the consumer perception of sensory quality and acceptability of yoghurt fortified with FD IP powder should be investigated.

The Optimization Study of Rheological Characteristics of Wind Power Grease Based on Gel-State

The gel-state grease plays a vital and indispensable role in the long-term operation of wind turbines. To reduce carbon emissions and increase the reliability of wind turbines, this paper takes the gel-state Mobil SHC 461WT grease as the study object. Firstly, the rheological properties of the gel-state Mobil SHC 461WT grease were investigated using the Anton Paar MCR302 rotational rheometer. Secondly, the rheological characteristics of three different gel states of the Mobil SHC 461WT grease (additive content of 0.1% of RFM3000, SK3115, and PV611, respectively, in the gel-state Mobil SHC 461WT grease) were optimized under the same conditions. Finally, according to the experimental results and the Herschel-Bulkley (H-B) model, the RFM3000 additive has the best effect on improving the rheological characteristics of the gel-state Mobil SHC 461WT grease. This research provides a new idea and direction for the technological advancement of the gel-state grease industry.

Physical and Chemical Properties, Flavor and Organoleptic Characteristics of a Walnut and Purple Rice Fermented Plant Drink

In recent years, green and healthy foods have attracted much attention. Plant-based foods have become an alternative to animal-derived foods. In this study, we used walnut and purple rice as the primary raw materials to produce a fermented plant drink. The process included boiling, mixing, grinding, inoculation, fermentation, and sterilization. We then analyzed the similarities and differences between the resulting walnut and purple rice fermented plant drink and an unfermented walnut and purple rice plant drink, as well as dairy-based yoghurt, in terms of physical chemistry, flavor, and sensory characteristics. We also examined the similarities and differences between the walnut and purple rice fermented plant drink and room-temperature yoghurt. The study results revealed that the walnut and purple rice fermented plant drink exhibited greater viscosity than the walnut and purple rice unfermented plant drink and room-temperature yoghurt. Additionally, the former displayed enhanced stability and recovery ability. Notably, distinguishable differences were observed between the three samples in terms of the presence of unknown volatiles and the umami signal, as indicated by electronic nose/tongue and GC-IMS analyses. The umami flavor of the walnut and purple rice fermented plant drink surpasses that of room-temperature yoghurt, while its taste is less salty than that of the walnut and purple rice plant drink. Despite possessing a weaker aroma than dairy-based yogurt, it is more potent than the walnut and purple rice plant drink. Additionally, its relative abundance of olefins, ketones, and alcohols enhances its unique flavor profile, surpassing both other options. Based on sensory analysis, it can be deduced that walnut and purple rice fermented plant drink has the highest overall acceptance rate.

Critical review on anthocyanins in blue honeysuckle (Lonicera caerulea L.) and their function

Blue honeysuckle (Lonicera caerulea L.) is an emerging commercial fruit in the world, has been known for its multiple anthocyanins in the berries, cyanidin-3-glucoside (C3G) is a major anthocyanin in berries and it makes up 76-92% of the total anthocyanins content, with high antioxidant capacity, and widely used in food products. In this review, recent studies related to anthocyanins in blue honeysuckle were sorted out, including the current status of research on anthocyanins in blue honeysuckle berries, especially C3G, qualitative and quantitative analysis of anthocyanins in berries, extraction and purification methods of anthocyanins from blue honeysuckle, in addition, biological effects of blue honeysuckle, and recommended utilization. Blue honeysuckle contains polyphenols, flavonoids, anthocyanins, minerals, and multiple bioactive compounds, it has been extensively reported to have significant antioxidant, cardioprotective, anti-inflammatory, neuroprotective, anticancer, and anti-diabetic functions, and has been used in a variety of food products as raw materials.

Application of natural and modified additives in yogurt formulation: types, production, and rheological and nutraceutical benefits

Yogurt, a popular fermented dairy product, is of different types and known for its nutritional and nutraceutical benefits. However, incorporating additives into yogurt has been adopted to improve its functionality and nutraceutical properties. Additives incorporated in yogurt may be natural or modified. The incorporation of diverse natural additives in yogurt formulation, such as moringa, date palm, grape seeds and argel leaf extracts, cornelian cherry paste, mulberry fruit and leaf powder, lentil flour, different types of fibers, lemongrass and spearmint essential oils, and honey, has been reported. Similarly, modified additives, such as β-glucan, pectin, inulin, sodium alginate, and gelatin, are also added to enhance the physicochemical, textural, sensory, and rheological properties of yogurt. Although additives are traditionally added for their technological impact on the yogurt, studies have shown that they influence the nutritional and nutraceutical properties of yogurt, when added. Hence, yogurts enriched with functional additives, especially natural additives, have been reported to possess an improved nutritional quality and impart several health benefits to consumers. These benefits include reducing the risk of cardiovascular disease, cancer, osteoporosis, oxidative stress, and hyperglycemia. This current review highlights the common types of yogurt, the production process, and the rheological and nutraceutical benefits of incorporating natural and modified additives into yogurt.

Techno-Functional and Sensory Characterization of Commercial Plant Protein Powders

Many new plant proteins are appearing on the market, but their properties are insufficiently characterized. Hence, we collected 24 commercial proteins from pea, oat, fava bean, chickpea, mung bean, potato, canola, soy, and wheat, including different batches, and assessed their techno-functional and sensory properties. Many powders had yellow, red, and brown color tones, but that of fava bean was the lightest. The native pH ranged from 6.0 to 7.7. The water solubility index was 28% on average, but after heat treatment the solubility typically increased. Soy isolate had by far the best water-holding capacity of 6.3 g (H₂O) g^-1, and canola had the highest oil-holding capacity of 2.8 g (oil) g^-1. The foaming capacity and stability results were highly varied but typical to the raw material. The emulsification properties of all powders were similar. Upon heating, the highest viscosity and storage modulus were found in potato, canola, and mung bean. All powders had raw material flavor, were bitter and astringent, and undissolved particles were perceived in the mouth. Large differences in functionality were found between the batches of one pea powder. In conclusion, we emphasize the need for methodological standardization, but while respecting the conditions found in end applications like meat and dairy analogs.

Effect of retrograded starch with different amylose content on the rheological properties of stored yogurt

Resistant starch (RS) promotes health benefits; however, when added to foods, it could change the rheological properties. The effect of adding different concentrations (2.5, 5, 7.5, and 10%) of retrograded corn starch with 27% (RNS) or 70% (RHS) amylose content on the properties of yogurt was evaluated through measurements of flow behavior and gel structure. Syneresis and resistant starch content were also assessed. Results were analyzed using multiple regression to describe the effect of starch concentration and storage time on the properties of yogurt added with RNS or RHS. Syneresis was reduced, RNS reinforced the structure increasing the water absorption capacity and the consistency index; meanwhile, RHS provided a yogurt containing up to 10 g of RS in 100 g of sample, allowing obtaining a functional dairy product. Creep-recovery test showed that adding RNS or RHS favored the matrix conformation, and the yogurt samples were able to recover. The final product behaved like a solid material with a firmer and more stable gel structure, resulting in a strengthened gel without weakening the yogurt structure, showing a characteristic like Greek-style or stirred yogurt depending on the type and concentration of retrograded starch.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05735-x.

Shaping the Physicochemical, Functional, Microbiological and Sensory Properties of Yoghurts Using Plant Additives

Nowadays, consumers pay particular attention to the quality of the products they buy. They also expect a high level of innovation. Hence, the offer from the dairy sector is increasingly focusing on the use of various additives with proven health benefits. Many scientific teams from various regions of the world are engaged in research, and their aim is to identify plant additives that have beneficial effects on the human body. The aim of this article was to summarize the latest literature pertaining to the effects of plant additives used in the production of yoghurts on their physicochemical, functional, microbiological and sensory properties. It was found that a wide range of additives in a variety of forms are used in the production of yoghurts. The most common include fruits, vegetables, cereals, nuts, seeds, oils, plant or herbal extracts, fruit or vegetable fibre, and waste from fruit processing. The additives very often significantly affected the physicochemical and microbiological characteristics as well as the texture and sensory properties of yoghurt. As follows from the analysed reports, yoghurts enriched with additives are more valuable, especially in terms of the content of health-promoting compounds, including fibre, phenolic compounds, vitamins, fatty acids and minerals. A properly selected, high quality plant supplement can contribute to the improvement in the generally health-promoting as well as antioxidant properties of the product. For sensory reasons, however, a new product may not always be tolerated, and its acceptance depends mainly on the amount of the additive used. In conclusion, "superfood" yoghurt is one of the products increasingly recommended both preventively and as a way of reducing existing dysfunctions caused by civilization diseases, i.e., diabetes, cancer and neurodegenerative diseases. The studies conducted in recent years have not shown any negative impact of fortified yoghurts on the human body.

Impact of Apple Pomace Powder on the Bioactivity, and the Sensory and Textural Characteristics of Yogurt

This study focused on the development of a yogurt with an improved structure, texture and antioxidant activity level, by using apple pomace (AP) powder that was obtained in large quantities during the production of juices. The objective was to determine the sensory, physicochemical, textural and antioxidant characteristics of yogurt with the addition of AP powder (0.2-1.0%), during its shelf life. The physicochemical composition of AP was determined as follows: dietary fibers-62.73%, including pectin-23.12%; and the content of the antioxidant compounds in AP-total polyphenols (728.8 mg GAE/100 g DW), flavonoids (246.5 mg QE/100 g DW), tannins (63.54 mg TAE/100 g DW), carotenoids (4.93 mg/100 g DW) and the ability to inhibit the free radical (2433 µmol TE/100 g DW). AP addition reduces the yogurt fermentation time. The increase in the total dietary fiber content of up to 0.63% and in the insoluble fiber of up to 0.14% was attested in this study, as well as a significant increase in antioxidant activity, which correlated to the AP content. The addition of AP improved the textural properties of the yogurt during storage (20 days) and led to a significant reduction in syneresis. The influence of the AP content and the storage period on the textural characteristics and the overall acceptability of the yogurt samples were analyzed by the mutual information method. The AP content greatly influenced the yogurt's quality, with the information analysis value for the overall acceptability being 0.965 bits. The analysis of the sensory and textural parameters of the yogurt during storage (1-20 days) demonstrated that samples with AP in proportions of 0.6-0.8% were evaluated with the highest score.

Incorporation of Blue Honeysuckle Juice into Fermented Goat Milk: Physicochemical, Sensory and Antioxidant Characteristics and In Vitro Gastrointestinal Digestion

The addition of fruit juice may improve the physicochemical and functional characteristics of dairy products. The study evaluated the effect of 1−6% (v/v) blue honeysuckle juice (BHJ) on the physicochemical, sensory and antioxidant characteristics of fermented goat milk (FGM) during 21 days of refrigerated storage and in vitro gastrointestinal digestion. The incorporation of BHJ significantly increased (p < 0.05) the water-holding capacity, viscosity, redness (a*) value, total phenolic content (TPC) and ferric ion-reducing antioxidant power during storage. Additionally, BHJ affected the microstructure and sensory score of the samples. FGM treated with 4% (v/v) BHJ exhibited the highest overall acceptability. The supplementation of BHJ diminished the goaty flavor and promoted in vitro protein digestion. Furthermore, the TPC was enhanced in addition to the antioxidant activity of FGM containing BHJ throughout the in vitro digestion. Therefore, FGM supplemented with BHJ serves as a novel and attractive goat dairy product.