Giovana B. Celli

Annatto-entrapped casein-chitosan complexes improve whey color quality after acid coagulation of milk

A fraction of annatto is often transferred to the whey fluid during Cheddar cheese processing, which negatively impacts the visual and sensory attributes of the resultant whey powder. Alternatives to reduce the color in the powder are still needed. In this study, casein-chitosan complexes were prepared to deliver annatto preferentially to the curd and reduce the amount of carryover colorant in whey powder. These complexes were relatively spherical, with a mean complex diameter of 8.3u202f±u202f1.9u202fµm, zeta-potential of +39.4u202f±u202f1.3u202fmV, and entrapment efficiency of 38.2u202f±u202f3.1%. FT-IR spectroscopy confirmed the electrostatic interaction between casein and chitosan. Complexes and commercial annatto powder were incorporated into homogenized, reduced-fat, and fat-free milk, and subjected to acid coagulation. Whey powder produced from casein-chitosan-complex-treated samples exhibited better color quality than that prepared with annatto powder, indicating that the approach considered in this study was efficient in preventing the migration of colorant to the whey.

Polyelectrolyte Complex Inclusive Biohybrid Microgels for Tailoring Delivery of Copigmented Anthocyanins

This study fabricated a novel biohybrid microgel containing polysaccharide-based polyelectrolyte complexes (PECs) for anthocyanins. Herein, anthocyanins were encapsulated into PECs composed of chondroitin sulfate and chitosan, followed by incorporation into alginate microgels using emulsification/internal gelation method. We demonstrated that PECs incorporation strongly affected the properties of microgels, dependent on the polysaccharide concentration and pH in which they were fabricated. The dense internal network surrounded by an alginate shell was clearly visualized in cross-sectioned PECs-microgels. Stability studies carried out under varying ionic strength and pH conditions demonstrated the stimuli-responsiveness of the PECs-microgels. Additionally, the presence of PECs conferred microgels with high rigidity during freeze-drying and excellent reconstitution capacity upon rehydration. These observations were attributed to the modulation of electrostatic and hydrogen-bonding cross-linking between PECs and the alginate gel matrix and suggest the PECs inclusive microgels hold promise as delivery vehicles for the controlled release of hydrophilic bioactive compounds.

Controlling the Release from Enzyme-Responsive Microcapsules with a Smart Natural Shell

We design a natural and simple core-shell-structured microcapsule, which releases its cargo only when exposed to lipase. The cargo is entrapped inside a gel matrix, which is surrounded by a double-layer shell containing an inner solid lipid layer and an outer polymer layer. This outer polymer layer can be designed according to the intended biological system and is responsible for protecting the microcapsule architecture and transporting the cargo to the desired site of action. The lipid layer contains natural ester bonds, which are digested by lipase, controlling the release of cargo from the microcapsule core. To demonstrate the feasibility of this approach, our model system includes a colorant bixin entrapped inside a κ-carrageenan gel matrix. This core is surrounded by an inner beeswax-palmitic acid layer and an outer casein-poloxamer 338 layer. These fabricated microcapsules are then applied into Cheddar cheese, where they selectively color the cheese matrix.

Two-Level Factorial Designs

We now change our focus from the number of factors in the experiment to the number of levels those factors have. Specifically, in this and the next several chapters, we consider designs in which all factors have two levels. Many experiments are of this type. This is because two is the minimum number of levels a factor can have and still be studied, and by having the minimum number of levels (2), an experiment of a certain size can include the maximum number of factors. After all, an experiment with five factors at two levels each contains 32 combinations of levels of factors (25), whereas an experiment with these same five factors at just one more level, three levels, contains 243 combinations of levels of factors (35) – about eight times as many combinations! Indeed, studying five factors at three levels each (35 = 243 combinations) requires about the same number of combinations as are needed to study eight factors at two levels each (28 = 256). As we shall see in subsequent chapters, however, one does not always carry out (that is, “run”) each possible combination; nevertheless, the principle that fewer levels per factor allows a larger number of factors to be studied still holds.

Introduction to Taguchi Methods

We have seen how, using fractional-factorial designs, we can obtain a substantial amount of information efficiently. Although these techniques are powerful, they are not necessarily intuitive. For years, they were available only to those who were willing to devote the effort required for their mastery, and to their clients. That changed, to a large extent, when Dr. Genichi Taguchi, a Japanese engineer, presented techniques for designing certain types of experiments using a “cookbook” approach, easily understood and usable by a wide variety of people. Most notable among the types of experiments discussed by Dr. Taguchi are two- and three-level fractional-factorial designs. Dr. Taguchi’s original target population was manufacturing engineers, but his techniques are readily applied to many management problems. Using Taguchi methods, we can dramatically reduce the time required to design fractional-factorial experiments.

Synergistic Bathochromic and Hyperchromic Shifts of Anthocyanin Spectra Observed Following Complexation with Iron Salts and Chondroitin Sulfate

Grape anthocyanins are not traditionally used on complexation studies, as the main compounds lack a catechol group. In this study, concomitant metal complexation (Fe2+ and/or Fe3+) and co-pigmentation with chondroitin sulfate (CHS) were shown to synergistically affect the color spectra of grape anthocyanins at varying pHs. In general, the addition of iron salts resulted in small reductions in maximum absorbance at pH 3 and a bathochromic shift at pH 4 and 5. On the other hand, CHS resulted in hypochromic shifts at pH 3 and 4. When combined, these compounds broadened the peak at higher wavelengths associated with blue color, and resulted in significantly higher (pu2009<u20090.05) area under the curve at these wavelengths even at pH 3. Interestingly, this synergistic effect seemed to work only at low pH. All observed effects were achieved using low concentrations of metals and CHS. The results should interest those aiming to achieve anthocyanin color modulation through metal complexation at modest loadings.

Tailoring Delivery System Functionality Using Microfluidics

Various methods are currently used by the food industry to investigate and prepare emulsions, encapsulates, and other structures. However, these techniques do not allow accurate control over processing variables, which can negatively impact the resultant product properties. In this context, microfluidic technology has been proposed as a powerful tool for the development of innovative food structures, given its use of small amounts of fluids and high reproducibility, resulting in monodisperse droplets and particles. These benefits prove useful when a researcher is interested in investigating the fundamental effects of specific variables while keeping the others under precise control. This review presents an overview of the use of microfluidic devices as technological tools for the preparation of innovative food products and discusses their potential for the development of tailored delivery systems.

Quantitative comparison of adsorption and desorption of commonly used sweeteners in the oral cavity

Adsorption-desorption properties of different sweeteners in the oral cavity were evaluated using high performance liquid chromatography-based methodology. Three low calorie artificial sweeteners (aspartame, acesulfame potassium and sucralose), one steviol glycoside (rebaudioside A), and high fructose corn syrup (HFCS) were examined and compared with sucrose at pH 3 and 7 in a model beverage matrix. Results indicated that HFCS had the highest adsorption in the oral cavity, followed by rebaudioside A and the artificial sweeteners. The physicochemical interaction between sweeteners and salivary proteins did not affect the adsorption properties significantly as validated from a series of characterization techniques.

Designs with Three or More Factors: Latin-Square and Related Designs

When more than two factors are under study, the number of possible treatment combinations grows exponentially. For example, with only three factors, each at five levels, there are 53 = 125 possible combinations. Although modeling such an experiment is straightforward, running it is another matter. It would be rare to actually carry out an experiment with 125 different treatment combinations, because the management needed and the money required would be great.

Some Further Issues in One-Factor Designs and ANOVA

We need to consider several important collateral issues that complement our discussion in Chap. 2. We first examine the standard assumptions typically made about the probability distribution of the e’s in our statistical model. Next, we discuss a nonparametric test that is appropriate if the assumption of normality, one of the standard assumptions, is seriously violated. We then review hypothesis testing, a technique that was briefly discussed in the previous chapter and is an essential part of the ANOVA and that we heavily rely on throughout the text. This leads us to a discussion of the notion of statistical power and its determination in an ANOVA. Finally, we find a confidence interval for the true mean of a column and for the difference between two true column means.