Yoghurt System Research Articles

Measuring shared value creation with eco-efficiency: Development of a multidimensional value framework for the dairy industry

The concept of creating shared value was first advanced by Harvard Business School and adopted by companies to develop sustainability strategies to maximize their positive impacts on society. Eco-efficiency is a sustainability concept and a prevalent operational decision support tool that assesses the environmental performance of a system as a function of its value. This paper proposes a novel multidimensional value eco-efficiency framework based on a life cycle perspective that broadens the value dimension assessment in keeping with the concept of creating shared value. The framework is tested and implemented in a case study in the Canadian dairy industry. It uses a systemic approach to compare the eco-efficiency performance of 11 multifunctional Greek yogurt systems delivering various co-products with different functions and economic values across the value chain. It makes it possible to identify the trade-offs between the environment and various value dimensions (economic or functional) based on stakeholders' interests. The results show that the scenarios that create the most economic value for the Greek yogurt processors do not perform as well for the other stakeholders along the value chain or in terms of overall environmental performance. By developing a multi-criteria value assessment, this enhanced eco-efficiency framework brings consistency in covering the same scope of analysis between value creation and environmental impacts. More specifically it breaks with the industry's prevailing value creation philosophy and value measurement in eco-efficiency analysis, which is usually based on cost-effectiveness and profit maximization for one stakeholder at the expense of the others in the value chain. Ultimately, it contributes to align companies' efforts in improving their eco-efficiency with sustainability goals and minimize the risk of burden shifting.

Milk solids replacement with chickpea flour in a yogurt system and their impact on their physicochemical, rheological, and microstructural properties during storage

Yogurt is one of the most widely consumed foods around the world, with a tendency to add several ingredients with functional properties. The incorporation of legume flours in food systems has been a growing trend in recent years. Therefore, this study evaluated the effect of the addition of chickpea flour on the physicochemical, rheological, and microstructural properties of yogurt. Different levels of chickpea flour (1, 2, and 3%) were added to yogurt and the evolution of systems were monitored on days 1, 8, 15, and 22 of storage. Results for pH (4.61 – 4.75), titratable acidity (0.58% - 0.72%) and density (1048 - 1139 kg/m3) showed no significant differences (p > 0.05), while higher concentrations of the flour resulted in lower levels of syneresis (15.90% - 23.73%). The flow properties confirmed the non-Newtonian behavior in the systems, fitting the two Power Law and Herschel-Bulkley models, thus establishing a relationship between the experimental data and the variables under study. The microstructure analysis showed that a higher concentration of chickpea flour increases the porosity of the system. Finally, the results suggest that it is highly recommended to replace milk solids with chickpea flour, thereby maintaining the properties and stability of the product.

Rheological properties of xanthan-modified fish gelatin and its potential to replace mammalian gelatin in low-fat stirred yogurt

Fish gelatin (FG) has been modified to replace mammalian gelatin, but has not been applied in the yogurt production. In this study, xanthan gum (XG) was used to improve the rheology properties of FG, and the XG-modified FG was applied in acid milk gels and low-fat yogurts to mimic the rheology and texture properties of porcine gelatin (PG). No obvious difference in the storage moduli was observed for the FG gels (2.5 g/100 g) with the addition of XG from 0 to 0.05 g/100 g, while increasing addition of XG increasingly impeded the gelation process of FG. Moreover, in the milk gel system with FG addition (0.4 g/100 g), an increase in the XG proportion caused an increase in the storage moduli. Milk gels with a XG to FG ratio of 1:99 best mimicked the storage moduli of milk gels with PG. In the yogurt system, yogurt with 0.4 g/100 g XG-modified FG had better water-holding capacity and consistency than the yogurt with 0.4 g/100 g PG, and had similar viscosity, pseudoplasticity, and thixotropy to yogurt with 0.4 g/100 g PG. The results suggested that XG-modified FG is a promising replacement for mammalian gelatin in low-fat stirred yogurt.

Ability to detect and identify the presence of particles influences consumer acceptance of yoghurt

The common practice of particle addition into semisolid foods is known to influence sensory textural properties, but the resulting influence on consumer acceptability is not well understood. A systematic trial was therefore designed, involving a set of nine yoghurt samples, to investigate the effect of particle addition on consumer acceptability. Agar microgels were fabricated and added to yoghurt at varying levels of modulus (210 kPa or 550 kPa, fabricated with 5% or 10% agar, respectively), particle size (30 μm or 100 μm) and particle concentration (2% or 5%, w/w). The yoghurt samples were presented to consumers (n = 117), who rated acceptability, and subsequently selected from the attributes particles, drying, sweet, smooth, no particles and none of these by ‘check all that apply’ (CATA), for each sample. On average, all samples were generally well-liked by consumers, although samples containing 5% (w/w) particles were less acceptable than those containing 2% (w/w) particles. Consumer cluster analysis was used to identify groupings of consumers based on difference in acceptability scores. Acceptability scores for the yoghurts were lower for the consumers who selected the attribute particles in the higher modulus samples. Addition of particles (30 μm or 100 μm) at 550 kPa modulus and 5% (w/w) particles was identified as the threshold of particle detection in this yoghurt system and the point at which acceptability scores declined.

Stirred-type yoghurt incorporated with sour cherry extract in chitosan-coated liposomes

Liposomal systems are promising carrier systems for the delivery of phenolic compounds. However, the commercial usage of aqueous liposomal dispersions is still challenging. In this study, an aqueous liposomal dispersion which was loaded with sour cherry phenolics (SCE) were converted into powder form by spray drying to make the use of such delivery systems industrially applicable. Then, the obtained SCE loaded liposomal powder was incorporated into a stirred-type yoghurt system. During 21-day storage at 4 °C, sensorial and physicochemical properties such as pH, color, and whey syneresis of yoghurt with SCE loaded liposomal powder were investigated. According to the results, SCE was successfully encapsulated in aqueous liposomal dispersion and spray dried. Spray drying process did not degrade phenolic compounds that were encapsulated by liposomes. The structure of liposomes in the sample contained spray dried liposome encapsulates with SCE (Y-encapsulated SCE) was the most stable in yoghurt during storage which also affects the stability of SCE. Thus, SCE showed the lowest degradation level in this sample among all samples in terms of total phenolics and antioxidant capacity. This means that the SCE in yoghurt with liposomal encapsulates was protected during the storage period. The spray drying process also led to an increased total dry solid and reduced syneresis. Although syneresis of yoghurt containing liposomal powder with SCE and without SCE was the lowest, control yoghurt was chosen to be the best according to the sensorial evaluation.

Adding apple pomace as a functional ingredient in stirred-type yogurt and yogurt drinks

Apple pomace (AP) was processed into a freeze-dried powder to add into stirred-type yogurt to create 1, 2, and 3% (w/w) AP-fortified yogurt. Both texture analysis and rheological testing were used to evaluate the effect of AP on the structure and texture of yogurt during cold storage. The results indicated that apple pomace altered the structure of stirred yogurt, making it firmer and more cohesive, increased its viscosity and significantly reduced whey release during cold storage. Stronger influence on the parameters was observed at higher AP concentrations. Apple pomace added to a diluted yogurt system has the potential to stabilise the acid drink and reduce the sedimentation of protein aggregates. Addition of AP to already fermented milk gel allowed a higher concentration of AP (up to 6% w/w) to be incorporated, which made the stirred yogurt and yogurt drinks a vehicle for delivering a higher level of dietary fibre and phytochemicals (as compared to AP added to milk prior to fermentation). This study demonstrated that apple pomace has a potential as a natural stabiliser as well as a dietary fibre source in stirred type yogurts and yogurt drinks.

Modulating the physical state and functionality of phytosterols by emulsification and organogel formation: Application in a model yogurt system

The size of phytosterols crystals affects their bioactivity, with smaller crystals exerting a more competitive action against cholesterol absorption. The aim of this study was to decrease their crystal size by incorporating phytosterols in emulsion droplets along with γ-oryzanol (organogel formation) and thus hindering phytosterol crystallization, which could result in an increased efficacy of these bioactives. Phytosterols crystallization commences at concentration of 3% (w/w) in oil. However, in emulsions containing phytosterols, no crystals were formed up to 15% (w/w). Addition of γ-oryzanol to phytosterol-oil solutions further inhibited crystal formation. The mechanical properties of the emulsions and yogurt products containing phytosterols were found to be dependent on the extent of phytosterol crystallization. Emulsification of phytosterol-oryzanol oil solutions can be an expedient method to tune the rheological properties, increase phytosterol solubility in the food matrix, and likely enhance their physiological function in the gut environment.

Sonication induced particle formation in yogurt: Influence of the dry matter content on the physical properties

Yogurt texture can be adjusted by various compositional and processing factors. The factors protein content and type, heat treatment, and fermentation temperature are well-known and studied. In a previous study we were able to show sonication as an additional parameter affecting texture. The aim of this study was to test the hypothesis that sonication during fermentation induces large particles which, thus, have an impact on the texture perception of stirred yogurt. 26 stirred yogurt systems, differing in the fat (0.1−3.5%) and protein content (3.8−5.2%) were produced and a short sonication (35 kHz, 5 min) was applied within the pH range 5.1–5.2. Image analysis was performed to quantify the number and size of visually detectable particles/grains. Furthermore, the physical properties were studied by means of static light scattering and rheological measurements. Multivariate data analysis was used to discriminate between the effects of sonication and dry matter. Sonication resulted in new larger particles whereas an increase in dry matter content mainly affected the rheological properties. Above a dry matter content of 14.2%, no significant effect of the sonication was distinguishable.

Interaction of starch and casein

Starch was commonly used to improve the stability of set yogurt. In this research, casein and modified starches were placed in a simulated yoghurt system giving the advantage of a low variation in the environment parameters compared to a natural yoghurt system. The interactions between modified starches (phosphate starch, hydroxypropyl starch and starch ester of octenyl succinic) and casein were investigated with several independed types of measurements methods. The combination of zeta potential and fluorescence micrograph were used to research the interactions between modified starches and casein. And the results proved that modified starches not only absorbed with casein via electrostatic forces, but also had steric stabilization. Besides this, fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to investigate the role of hydrogen bonds between modified starches and casein. It could be deduced that the interactions of modified starches and casein included electrostatic adhesion, steric stabilization and hydrogen bond. At the same time, electrostatic adhesion was the main interaction between phosphate starch and casein. The main role of the interactions between starch ester of octenyl succinic and casein should be steric stabilization.

The interaction between casein and hydroxypropyl distarch phosphate (HPDSP) in yoghurt system

The hydroxypropyl distarch phosphate (HPDSP) was added to set yoghurt system as stabilizer in present work. Herein, the interaction between casein and HPDSP was researched. During the course of the study, casein and modified starch were placed in a simulation yoghurt environment in order to facilitate the observation and research. Light microscope and atomic force microscope (AFM) were applied to observe the microstructure of the samples. Results revealed that the aggregate degree of protein was decreased with adding HPDSP. The AFM micrograph proved that some protein particle adsorption on the surface of starch granule at pH 3.8. Dynamic light scattering (DLS) measurement indicated that particle size decreased with the concentration of modified starch increasing. Through zeta potential measurement, we hold opinion that casein particles absorb on the surface of the HPDSP via electrostatic forces. The research shows that the stability of modified starch is the result of “electrostatic repulsion” and “steric stabilization”.

Effect of cross-linked acetylated starch content on the structure and stability of set yoghurt

In this research, the effect of cross-linked acetylated starch on the set yoghurt system was studied by investigating the flowability, viscoelasticity, zeta potential, conductivity and microstructure of the set yogurt system. The results indicated that the stability, elastic modulus (G′) and viscous modulus (G″) of the set yogurt system increased as the concentrations of cross-linked acetylated starch increased. The set yogurt system, which added the cross-linked acetylated starch, exhibited shear-thinning behavior and belonged to yield pseudoplastic fluid. The SEM micrographs demonstrated that the microstructures of set yoghurt were mainly composed by the network of casein. By adding cross-linked acetylated starch, the network of casein was strengthened, and both conductivity of the yoghurt system and particle size of casein micelles due to absorption of modified starch revealed the aggrandizement trend. It can be deduced that the starch adsorbs onto the surface of the casein micelle and this phenomenon prevents flocculation of the casein micelles owing to electrostatic adhesion, steric stabilization and osmotic effect.

Relating Creamy Perception of Whey Protein Enriched Yogurt Systems to Instrumental Data by Means of Multivariate Data Analysis

Yogurts differing in fat content, protein content, and casein to whey protein ratio were produced, and structurally as well as sensorially examined. The objective of the current research was to evaluate the predictive value of rheological and particle size measurements concerning sensory appearance and texture attributes in 13 differently composed stirred yogurt systems, with a focus on graininess, viscosity, and creaminess. Structural and sensory analyses showed large differences in texture properties between the tested yogurt systems. Both data sets were correlated by means of multivariate statistical methods. Sensory graininess was highly correlated with particle size-related parameters, sensory viscosity was highly correlated with destructive rheological parameters, and creamy perception was highly correlated with particle size-related parameters and destructive rheological parameters but was not as well described by any oscillatory parameter. Best predictive ability (r(2) > 0.89) was found for creaminess combining particle size related- and destructive rheological parameters tested within this study. Knowing the instrumental parameters describing sensory textural attributes provides important information for having a better understanding of the underlying processes during consumer's perception. Knowledge about the sensory behavior of a product and its oral processing imparts an opportunity to fasten the product development process. By means of yogurt systems instrumental parameters derived from particle size analysis and rheological measurements were correlated with sensory attributes in order to determine the main factors leading to the mouthfeel sensations grainy, viscous, and creamy of semisolid milk products.

Determination of Color, Pigment, and Phenolic Stability in Yogurt Systems Colored with Nonacylated Anthocyanins from Berberis boliviana L. as Compared to Other Natural/Synthetic Colorants

Anthocyanins are of interest to the food industry because of their antioxidant power, attractive color, and stability in high acid foods. Powder from the Peruvian berry Berberis boliviana Lechler, rich in nonacylated anthocyanins (7% to 8% dry weight), was incorporated into yogurt samples containing 3 different fat levels. Color (CIE L, a, b, chroma, and hue angle), pigment (monomeric anthocyanin and polymeric color), and total phenolics were monitored over 8 wk of storage and compared to yogurt treatments containing purple carrot acylated anthocyanins, red beet betalaines, or FD&C Red nr 40. Anthocyanin profiles were analyzed by HPLC coupled to photodiode array and mass detectors. Color of yogurt containing B. boliviana anthocyanins at 20 mg cyanidin-3-glucoside (cy-3-glu) equivalents/100 g yogurt (L*= 65, chroma = 14, and hue angle = 335 degrees ) was similar to commercial blueberry yogurt (L*= 65, chroma = 10.5, and hue angle = 341 degrees ). High color, pigment, and phenolic stability were observed in yogurts colored with B. boliviana, independent of the fat matrix. Acylated anthocyanins from purple carrot extracts exhibited increased stability with higher fat content. Anthocyanin degradation followed 1st-order kinetics. Pigment half-lives were 125 and 104 d for nonacylated anthocyanins at 10 and 20 mg cy-3-glu equivalents/100 g yogurt and 550.2, 232.6, and 128.9 d for acylated anthocyanins at 20 mg of cy-3-glu equivalents/100 g of 4%, 2%, and 0% fat yogurt. Addition of B. boliviana whole berry powder to yogurt matrices produced an attractive, stable anthocyanin-rich product, eliminating the need for industrial colorant extraction.

Influence of ferulic acid on stability of anthocyanins from Cabernet Sauvignon grapes in a model system and a yogurt system

SummaryThe influence of different factors on the stability of the anthocyanin crude extract from Cabernet Sauvignon grape skins was investigated. In a model system, the factors evaluated were as follows: temperature 4 ± 1 °C and 29 ± 3 °C, presence and absence of light, pH 3.0 and 4.0 and presence of ferulic acid. The influence of the addition of ferulic acid to anthocyanins was investigated in a yogurt system stored at 4 ± 1 °C. The results obtained for anthocyanin degradation velocity constant and for the half‐life time of anthocyanins in a model system and in a yogurt system showed that ferulic acid significantly increased the stability of the anthocyanins crude extract.

Viscosity of model yogurt systems enriched with barley β-glucan as influenced by starter cultures

The effect of barley β-glucan (BG) on the growth of two yogurt starter cultures (SCs) each consisting of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was investigated. Model yogurt systems were prepared with or without the incorporation of barley BG and lactose to mimic natural levels in milk and allowed to ferment for 8 h at 42 °C. The fermentation efficacy of the SCs was monitored through pH measurements. Samples were collected and analyzed for pH and viscosity at 0, 2, 4, and 8 h. Viscosity was determined using a rotational viscometer at shear rates of 1.29–129 s −1 and 20 °C. The pH measurements indicated no adverse effect on the growth of SCs as the acidification process was consistent with normal pH development, but viscosity measurements suggested that BG was depolymerized by SCs when lactose became a limiting nutrient during fermentation.

Caffeic acid copigmentation of anthocyanins from Cabernet Sauvignon grape extracts in model systems

Caffeic copigmentation of anthocyanins from Cabernet Sauvignon grape extracts in model system and yoghurt model system was investigated, as well as the influence of copigmentation on the stability of these pigments. In the model system, the dependence of anthocyanin stability on added caffeic acid was evaluated at temperatures (4 ± 1 °C and 29 ± 3 °C) and in the presence or absence of light, at two pH values: 3.0 and 4.0; in the yoghurt model system, the stability of the anthocyanins was evaluated at 4 ± 1 °C in the dark. The half-life and percentage of color retention of the anthocyanins in all treatments was calculated. The spectrophotometric results (Δ λ, Δ A) revealed that interaction occurred between the crude extract of anthocyanins and caffeic acid suggesting copigmentation. The addition of caffeic acid (1:1 w/v) significantly increased ( p < 0.05) the stability of anthocyanins in both model and yoghurt systems. In the model system the temperature and presence of light significantly influenced the stability of anthocyanins ( p < 0.05), where the highest values for half-life were obtained for anthocyanins with caffeic acid at pH 3.0, stored in the dark at a temperature of 4 ± 1 °C (6.930 h). In the yoghurt system the caffeic acid increased the half-life time of anthocyanins to 6673 h.

RHEOLOGICAL AND PHYSICOCHEMICAL BEHAVIOR OF FORTIFIED YOGURT, WITH FIBER AND CALCIUM

ABSTRACT Yogurt systems were prepared from whole milk, adding 50 mg of calcium/100 mL of yogurt, and three levels of fiber from two wheat‐bran sources. In comparison with a plain yogurt, the presence of fiber and calcium augmented the consistency, diminished the syneresis and the pH was higher. Fiber increased the consistency, and all the formulated samples exhibited a non‐Newtonian response. During 3 weeks of storage time, the consistency reduced (from 2.0 to 0.32 Pa·s n ), syneresis increased (from 20 to 48%) and pH decreased (from 4.5 to 4.2) as a function of the system formulation.

Altering the fat content affects flavor release in a model yogurt system.

Flavored yogurts differing in fat content were eaten, and the release of flavor volatiles was measured by monitoring the volatile composition of air from the nose in real time by atmospheric pressure ionization mass spectrometry. Low-fat yogurts (0.2%) were found to release volatiles more quickly and at higher intensity but with less persistence than yogurts containing fat at 3.5 and 10% fat. Yogurts with increasing fat content had higher viscosity and lower relative particle size. Lipophilic compounds were more affected by fat for maximum volatile intensity, but not time-to-maximum intensity or persistence. Sensory assessment of the yogurts found significant differences in intensity and speed of onset of flavor, but not overall length of perception.

SENSORY DIFFERENCE TESTS: THURSTONIAN AND SSA PREDICTIONS FOR VANILLA FLAVORED YOGURTS

ABSTRACTThe Thurstonian prediction that judges will get a higher proportion of correct 3‐AFC tests than triangle tests was confirmed using a yogurt system. As predicted, d′ values for the triangle and 3‐AFC tests corresponded. Sequential Sensitivity Analysis predictions for the sensitivity of various tasting sequences were confirmed for the 3‐AFC test but not the triangle test. Further predictions that the 2‐AFC is more sensitive than the 3‐AFC were confirmed. This increase in sensitivity more than offset the greater statistical power of the 3‐AFC. Difficulties of specifying the nature of the difference for the 2‐AFC and 3‐AFC tests were overcome using a warm‐up procedure.

Starter culture effects on caprine yogurt fermentation

The growth rate of the starter culture and its effects on the gelation process of caprine milk were determined. Caprine milk was fermented using various levels of starter culture inoculum and the acidification, growth and gelation profiles were obtained. The caprine yogurt samples inoculated with lower starter culture levels (1% and 1.5% wlv) produced gel structures about eight to 10 times stronger than that made using a 2% v/v inoculum. The gelation patterns suggested that the formation of the gel structure during the caprine yogurt fermentation was time dependent. This behaviour may be due to the presence of higher cell numbers in the caprine yogurt system.