Textural, rheological, melting properties, particle size distribution, and NMR relaxometry of cocoa hazelnut spread with inulin-stevia addition as sugar replacer.

This study investigated the influence of substituting 60, 80, and 100% of the sugar in traditional cocoa hazelnut paste (control) formulation with inulin-stevia (90:10, w/w) mixture on textural and rheological characteristics, melting behavior, water activity (aw), particle size distribution (PSD), and color. Textural, rheological, melting properties, and color of samples were analyzed after 1, 2, and 3 months of storage at 11°C. Nuclear magnetic resonance (NMR) relaxometry experiments were also performed to understand the interaction of new ingredients with oil. Replacement of sugar with inulin-stevia gave darker color, reduced Casson yield stress, and changed the textural parameters and melting profile of the samples depending on the level but did not create a remarkable effect on PSD and Casson plastic viscosity. Increasing inulin-stevia content yielded lower aw and higher T2a values indicating decreased mobility of water. Complete removal of sugar caused low spreadability. The results showed that an 80% replacement level yielded a product with similar textural parameters and fat-melting mouth feeling compared to control sample. Cocoa hazelnut spreads prepared with inulin and stevia showed good textural stability during storage.

Use of magic sandwich echo and fast field cycling NMR relaxometry on honey adulteration with corn syrup.

BACKGROUND: Adulteration is defined as the intentional addition of a material that is not a part of the nature. In this study, a non-conventional time domain nuclear magnetic resonance (TD-NMR) pulse sequence: magic sandwich echo (MSE) was used to detect the adulteration of honey by glucose syrup (GS) and high fructose corn syrup (HFCS) accompanied with T1 and T2 relaxation times. Also, fast field cycling NMR (FFC-NMR) relaxometry and multivariate analysis were performed to investigate the adulteration. RESULTS: Higher maltose in GS and changing glucose to water ratio of HFCS gave high correlation with the crystal content values. In HFCS adulteration, two separate populations of protons having different T2 values were detected and T1 times were also used to determine GS adulteration. Addition of GS increased T1 while addition of HFCS increased T2 , significantly. CONCLUSION: The results showed that it is possible to differentiate the unadulterated and adulterated honey samples by using TD-NMR relaxation times and crystal content values obtained by the MSE sequence. By FFC-NMR relaxometry, not only GS addition but also the amount of GS was examined. The multivariate analysis technique of principal component analysis was able to distinguish the types of adulterants. © 2021 Society of Chemical Industry.

Single-Step Partial Purification of Intracellular ß-Galactosidase from Kluyveromyces lactis Using Microemulsion Droplets.

Partial purification of ß-galactosidase from the crude extract of Kluyveromyces lactis was carried out using water-in-isooctane microemulsions formed by the anionic surfactant, sodium di-ethylhexyl sulfosuccinate (Aerosol OT). In order to obtain the crude extract, yeast cells of K. lactis were disrupted by a cell disrupter and separated. The purification of ß-galactosidase from the extract by a recently developed one-step reversed micellar (i.e., microemulsion-based) extraction method was then tested, by measuring total protein mass and enzyme activity in the product stream and by analyzing its composition using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography. Effects of salt concentration, protein concentration, and pH on the extraction were investigated. Using this approach, a 5.4-fold purification of ß-galactosidase was achieved with 96 % total activity recovery, using a feed containing crude extract and 50 mM K-phosphate buffer (pH 7.5) and 50 mM KCl. Gel filtration chromatography showed that the single extraction was successful at removing low molecular weight impurity proteins (molecular weight (MW) < 42 kDa) from the crude extract.

One-step separation of ß-galactosidase from ß-lactoglobulin using water-in-oil microemulsions.

Solubilisation of ß-galactosidase from Kluyveromyces lactis in Aerosol-OT water-in-isooctane microemulsions was measured as a function of buffer type and concentration, pH, and protein concentration. For buffer concentrations above ∼40mM, the enzyme was largely excluded from the droplets. Based on these results, a one-step separation was developed. A protein-containing aqueous feed was injected into an AOT/isooctane solution, with the feed volume slightly in excess of the predicted water solubility. Impurity proteins were entrapped inside the microemulsion droplets that then formed in the organic phase, while the high MW target protein was excluded and entered a newly formed, excess aqueous phase. The separation of ß-galactosidase from the test protein ß-lactoglobulin was most complete at 100mM KCl salt concentration, where the droplets were large enough to carry ß-lactoglobulin but too small for ß-galactosidase. At 100mM [KCl], 92% of the total enzyme activity was recovered in a concentrated and virtually pure form.