Development of Quantitative Structure-Property Relationship (QSPR) Models of Aspartyl-Derivatives Based on Eigenvalues (EVA) of Calculated Vibrational Spectra Abstract In present study, validated linear quantitative structure-property (sweetness) relationship (QSPR) models were developed, based on an experimental sweetness index and the calculated vibrational spectra of 158 aspartyl-derivatives. The quantum chemical AM1 method was applied to calculate the vibrational spectra of the compounds. The EVA descriptors were derived from the vibrational spectra for a combination of various values of σ (2.5, 5, 10,20 and 40 cm−1) and L (5, 10, 20 and 40 cm−1), which were correlated with an experimental sweetness index of the compounds using the multiple linear regression method. Several QSPR equations were constructed and analyzed. Among the various combinations, the statistically best QSPR equations were achieved when σ =10 and L = 10 were chosen. Four equations were selected as QSPR models, namely, model_1, model_2, model_3 and model_4. Satisfactory statistical values were found for the fit of the training set, R2=0.618, 0.691, 0.605 and 0.604, internal validation Q2=0.540, 0.647, 0.550 and 0.548, and the external predictive measures for the test set, \( {R}_{pre.}^2 \)=0.614, 0.616, 0.633 and 0.633 were obtained for dubbed 1 to 4 respectively. The application domain of the models was determined. The results of the Y-randomization test of the models support the finding that the statistical values obtained for the QSPR models were not due to just chance. Graphic visualizations of the EVA profiles of some of the selected compounds showed that the presence of hydrophobic moiety in the structure such as those of saturated hydrocarbons, e.g. heptane in ASP_215, tert-butyl in ASP_63, cyclohexane in ASP_201 and pentane in ASP_199, which is related to a high sweetness index, might be monitored in the EVA profiles of aspartyl-derivatives.

Effects of Carrier Agents and Relative Humidity on the Physicochemical and Microstructural Characteristics of Hot Air-Dried Asian Pear ( Pyrus pyrifolia Nakai cv. Niitaka) Powder Abstract For improving the stability of Asian pear powder (APP), rice bran dietary fiber (RD) (used for the first time) and maltodextrin (MD) were employed as carrier agents; the physicochemical and microstructural characteristics of APP during room storage at various relative humidity (RH) levels for 25 days were then evaluated. The RD-containing APP had a higher glass transition temperature, increased flowability, smaller particle size, and lower water adsorption capacity compared to the MD-containing APP. The comparison of the RD- and MD-containing APP samples revealed that the former had a higher total phenolic content and antioxidant activity, and showed fewer changes in color and agglomeration at the various RH levels. It was evident that the cracked appearance of APP samples was related to the higher degradation rate of the total phenols and higher antioxidant activity, especially at RH levels above 54%, during storage. FT-IR spectroscopy showed the chemical changes in APP caused by the carrier agents and RH. The results of the present study indicate that RD improved the functionality and storage stability of APP compared to MD; RD could be used as a potential carrier agent.

How do Different Types of Emulsifiers/Stabilizers Affect the In Vitro Intestinal Digestion of O/W Emulsions? Abstract This study analyzes the influence of different types of molecules (tween, lecithin, xanthan gum, and methylcellulose) on the physical properties (flow behavior and particle size) and microstructure of oil-in-water (o/w) emulsions before and during in vitro intestinal digestion. The release of free fatty acids during a simulated intestinal stage has also been examined. The results show that various o/w emulsions present different rates and extents of lipolysis and that these differences are not primarily due to their rheological properties nor to the droplet size/surface area available for the action of lipase. Rather, the observed differences in the kinetics of lipolysis are most likely attributable to the nature and location of each type of molecule in their respective o/w emulsions as well as to their interactions with intestinal components. These results shed light on the mechanisms by which the interfacial layer controls lipid digestion, paving the way for a practical application of some of these emulsions in the production of foods used for regulating dietary lipid digestion in order to prevent and treat obesity and related disorders.

Effect of Ohmic Heating on the Formation and Texture of Acid Milk Gels Abstract This study aimed to describe the effects of ohmic heat treatment (OHT) of milk on the formation and properties of acid milk gels. The influence of voltage gradient (25, 40, 55 V/cm), holding time (2, 16, 30 min), and final temperature (45, 65, 75, 85 °C) on rheological properties and particle size distribution was measured during the gelation process. Texture properties and syneresis of the samples were evaluated at the end of the gelation process. Scanning electron microscopy (SEM) micrographs of the acid milk gels were also taken at pH 4.6(i.e., pI or Isoelectric point of casein). Results indicated that oscillatory time sweep tests were more accurate than particle size measurements in detecting gelation onset. Complex modulus values of the final gel showed that OHT of the milk at 25 V/cm and holding at 85 °C for 16 min gave rise to a 21% higher structural strength compared to when using the conventional heat treatment (CHT) where temperature was 85 °C and holding time and come up time were 30 and 20 min respectively. In other words, by using the OHT milk, the same gel strength as that of CHT 85 °C sample was obtained by spending 185 min instead of 328 min incubation time (i.e., 40% less time). Higher voltage gradient lowered the final gel strength when temperature and holding time kept constant at 85 °C and 16 min respectively. Results indicated that the gel firmness enhanced and the amount of syneresis decreased when CHT was replaced by OHT in the manufacturing process. SEM revealed that the protein matrices of ohmic heating samples appeared to be more compact and denser with smaller pore size than observed in the conventional gel. Results indicated that OHT of milk successfully improves the quality of acid milk gels and obviate the need for increasing dry matter concentration or using additives.

Structure Changes in Relation to Digestibility and IgE-Binding of Glycinin Induced by pH-Shifting Combined with Microbial Transglutaminase-Mediated Modification Abstract This study aimed to evaluate the effects of pH-shifting treatment combined with microbial transglutaminase (MTG)-mediated modification on the structure, digestibility, and IgE-binding of glycinin. Glycinin was incubated in acidic (pH 1.0) or alkaline (pH 13.0) solutions to induce protein structure to unfolding followed by refolding for 1 h at pH 7.0. Afterwards, glycinin was incubated with MTG under appropriate conditions. Sodium dodecyl sulfate polyacrylamide gel electropheresis(SDS-PAGE), circular dichroism, UV absorption spectra, and surface hydrophobicity were considered to measure the changes in the structure of glycinin. The digestibility and IgE-binding of glycinin were determined by Tricine-SDS-PAGE and ELISA, respectively. The results showed that pH 1.0 shifting caused the unfolding of the spatial structure of glycinin and the formation of some polymers via disulfide bond. After glycinin was incubated with MTG, the protein preferentially underwent embedding and folding. The acidic compound-modified glycinin was stable for digestion. Under pH 13.0 shifting treatment, glycinin was partially hydrolyzed, and the MTG-modified alkaline-treated glycinin was slightly affected with a good digestibility. Compound modification could reduce the IgE-binding of glycinin, especially under alkaline conditions. Our findings suggested that alkaline pH shifting combined with MTG cross-linking can be an efficient approach to reduce the IgE-binding of glycinin with a labile digestion.

Effect of Temperature on 3D Printing of Commercial Potato Puree Abstract The temperature and composition of food, during the printing process, maybe a key factor impacting on rheological properties. Currently, there is no evidence of authors analysing the effect of printing temperature on the characteristics of final products. The aim of this paper was to study the printability of potato puree when affected by printing variables, such as printing temperature and the composition of the potato puree. The printing temperature was studied at 10 °C, 20 °C and 30 °C, and the effect of the product composition on the printability was studied by analysing the rheological and textural properties. Viscosity-temperature profiles, flow curves and dynamic oscillation frequency analysis of potato puree were some of the techniques used in rheology analysis. Forward extrusion assays of formulated potato puree were used to study the compression force in the 3D printer. Results showed the formulation with higher content of dehydrated potato puree (38 g of dehydrated potato puree in 250 mL of whole milk) at a temperature of 30 °C were the most stable. The printability increase with the amount of the consistency index and the reduction of behaviour index. The mean force from extrusion test was correlated with printability but the effect of temperature did not help define this parameter.

Vegetable and Mineral Oil Organogels Based on Monoglyceride and Lecithin Mixtures Abstract We investigated the development of vegetable (VO) and mineral (MO) oil organogels using mixtures of a commercial monoglycerides (MGC) and saturated lecithin (LC). The MGC (2% wt/wt) and LC (0.25% to 2.5% wt/wt) concentrations used in the MGC-LC mixtures were below the minimal gelator concentrations in the oils. At the corresponding MolesMGC/MoleLC studied (1.5, 4.0, 7.6, and 15.3) we achieved the development of well-structured organogels in both oils. The highest elasticity (G’) of the MGC-LC organogels was achieved in each type of oil at different MolesMGC/MoleLC. Thus, in the MO we obtained the highest G’ at the lowest MolesMGC/MoleLC (i.e., the highest %LC) and in the organogels with the highest solid fat content (%SC). In contrast, in the VO we obtained the highest G’ at 15.3 MolesMGC/MoleLC (i.e., at the lowest %LC) corresponding to the organogels with the lowest %SC. This behavior suggested that a solvent dependent synergistic effect existed between the MGC and the LC. Additional experiments showed that the addition of water (2.5% to 10% of water/total mass of gelator) resulted in organogels with higher G’, particularly in the 1.5 MolesMGC/MoleLC organogels developed in the MO. The DSC and X-ray results showed that in the MGC-LC organogels the Lα to β polymorphic transition was limited, and thus the MGC-LC organogels did not show phase separation even after 12 months of storage at 15 °C. This behavior was accentuated in MGC-LC organogels developed in presence of water. Therefore, the use of MGC-LC systems open the possibility of developing organogels at lower concentrations than the concentration needed just by the use of monoglyceride. Additionally, the MGC-LC organogels achieve higher G’ with elastic recovery properties, and longer stability against phase separation than MGC organogels. This, particularly in the 1.5 MolesMGC/MoleLC organogels developed in MO with at least 5% of water/total mass of gelator.

Submaxillary Mucin: its Effect on Aroma Release from Acidic Drinks and New Insight into the Effect of Aroma Compounds on its Macromolecular Integrity Abstract Submaxillary mucin is a major component that defines the makeup and functionality of saliva. Understanding its structure and function during food intake is key to designing appropriate strategies for enhancing the delivery of flavour. In the present study, the hydrodynamic integrity of bovine submaxillary mucin was characterised under physiological and acidic conditions and it was shown to have a broad molecular weight distribution with species ranging from 100 kDa to over 2000 kDa, and a random coil type of conformation. A decrease in the pH of mucin appeared to result in aggregation and a broader molecular weight distribution, which was shown to correlate with a release of flavour compounds. Our study also provides indications that p-cresol may have an effect on the macromolecular integrity of mucin.

Physical and Textural Properties of Mayonnaise Prepared Using Virgin Coconut Oil/Fish Oil Blend Abstract Physical and textural properties of mayonnaise prepared using virgin coconut oil (VCO)/fish oil (FO) blends at different ratios were examined in comparison with that prepared using soybean oil (SO) as affected by storage time (30 days). At day 0, sample prepared with SO showed the highest L*, a*, and b* values among all the samples, whereas the lowest values were noticeable for VCO containing sample. At day 30 of storage, decreases in L*, and b*values of all mayonnaise samples were observed (p < 0.05). However, a* values were increased at day 30 of storage (p < 0.05). For texture analysis, highest firmness, consistency and cohesiveness were obtained for the sample containing SO. Increasing levels of FO in VCO/FO samples increased the firmness, consistency and cohesiveness. For all the samples, loss modulus (G″) values were lower than G′. After 30 days of storage, all samples demonstrated slight decreases in G′ and viscosity than freshly prepared mayonnaise (day 0). When the sample containing VCO/FO (90:10) blend was further characterized, slight difference was observed in microscopic structure and droplet size distribution before and after storage of 30 days. Increase in droplet size was noticeable because of coalescence after the storage. Overall, type of oil used for preparation of mayonnaise as well as storage time affected the physical properties including textural and rheological properties of mayonnaise.

Influence of Phospholipids Structure on the Physicochemical Properties and In Vitro Digestibility of Lactoferrin-Loaded Liposomes Abstract The instability of liposomal delivery system during passaging through the gastrointestinal tract (GIT) stimulates a demand to find a stable liposome. This research studied the implications of different types of phospholipids (different fatty acid chain length and saturation, various head group) on liposomal physiochemical properties and stability in the human GIT. The micropolarity of liposomal membrane increased with the decrease of chain lengths of phospholipids, while the morphology observation revealed that the liposomes formed by different phospholipids showed similar in appearance and shapes. The liposomes formed by C20:0 deformed more severely in simulated gastric fluid, while others exhibited slight changes in the membrane structure. In simulated intestinal fluid, pancreatic lipase and phospholipase A2, synergized with bile salts, damaged the bilayers structure of all liposomes, with the entrapped lactoferrin release and hydrolysis. Although the various phospholipid structures lead to some difference on the physicochemical properties (size and micropolarity), the enzymic influence displayed more significance during in vitro digestion compared to the types of wall materials. Current results could provide valuable information for the development of more stable and reliable food-grade liposomes in the GIT.