Alejandro G. Marangoni

Processed cheese as a polymer matrix composite: A particle toolkit for the replacement of milk fat with canola oil in processed cheese

In this study, we show that the replacement of milk fat with canola oil in a model caseinate-based imitation cheese product to increase its nutritional value can be done by treating processed cheese as a particle filled gel network. Using microscopy, model imitation cheese products with different lipid phases were found to have similar microstructures where fat or oil appears as inert particle fillers in a continuous protein network. Using a texture profile analyzer, we show that the textural properties of model imitation cheese are dependent on the material properties of the inert filler. Addition of rigid particle fillers generally results in greater reinforcement of the matrix (i.e., increased hardness). The addition of oat fiber particles at 5% volume fraction to model cheese containing 51% milk fat and 49% canola oil resulted in a product with similar functionalities (i.e., hardness, oil stability, and meltability) as that of model cheese containing 100% milk fat. The current study therefore shows that the addition of edible non-fat particles for matrix reinforcement can be used as an alternative method for reducing saturated fats in foods while keeping other desirable properties of the product.

Food-grade filler particles as an alternative method to modify the texture and stability of myofibrillar gels

A series of food grade particles were characterized for their potential as fillers in myofibrillar gels. The fillers were separated into (i) hydrophilic, insoluble, crystalline particles and (ii) starch granules. The particles used were microcrystalline cellulose, oat fiber and walnut shell flour, as well as potato and tapioca starches. Crystalline particles increased hardness and decreased recovery properties. Although all of these fillers decreased the T2 relaxation time of water, this was dependent on particle type and size. An increase in gel strength was observed with increasing filler content, which was attributed to particle crowding. Native potato starch was the most efficient at increasing liquid retention, while native tapioca was the least effective. Gel strength increased significantly only for the native potato and modified tapioca starches, but no effect on recovery attributes were observed for any of the starch varieties. The potato starches became swollen and hydrated to a similar extent during the protein gelation process, while the native tapioca starch gelatinized at higher temperatures, and the modified tapioca showed little evidence of swelling. T2 relaxometry supported this finding, as the meat batters containing native potato starch displayed two water populations, while the remaining starches displayed only a single population.

Physical Form of Dietary Fat Alters Postprandial Substrate Utilization and Glycemic Response in Healthy Chinese Men

Background: Dietary fats elicit various physiological responses, with the physical form of fat reported to alter fat digestion and absorption.Objectives: The primary aims were to compare the effects of dietary fat in 2 physical forms (liquid and oleogel) and 2 degrees of saturation (saturated and polyunsaturated) on postprandial energy expenditure (EE) and substrate oxidation, glycemia, and appetite.Methods: The study was a randomized, controlled crossover trial. Sixteen normal-weight, healthy Chinese men completed the study [mean ± SD age: 28 ± 6 y; body mass index (in kg/m2): 22.9 ± 3.1]. After an overnight fast, participants had their body weight measured and entered an indirect whole-room calorimeter (WRC). After baseline measurements, participants consumed orange juice and rice porridge alone (control), with 22.25 g coconut oil or sunflower oil or with 25 g coconut oleogel or sunflower oleogel in random order with a 5-d washout period between treatments. EE, substrate oxidation, capillary blood glucose, and appetite were measured over 195 min in a WRC. Participants completed a meal challenge to assess appetite. Test meals effects were compared by using repeated-measures ANOVA.Results: Fat saturation did not affect all study outcomes significantly. When data were pooled based on the physical form of dietary fat, EE did not differ. However, significantly higher carbohydrate oxidation (P = 0.03) and a trend of lower fat oxidation (P = 0.07) were found after the liquid oil than after the oleogel or control treatments. Postprandial capillary glucose was also significantly lower after the liquid oil than after the oleogel or control treatments (P < 0.001). Appetite was not affected by the physical form and the saturation of dietary fats.Conclusions: The saturation of dietary fat did not affect postprandial glucose, EE, substrate oxidation, or appetite. However, oleogel prevented the glycemic-lowering and fat-oxidation effects induced by liquid oil in Chinese men. Future work on oleogel should focus on cardiometabolic risk factors. This study was registered at clinicaltrials.gov as NCT02702726.

Matrix effects on the crystallization behaviour of butter and roll-in shortening in laminated bakery products

Two hydrogenated roll-in shortenings (A & B), one non-hydrogenated roll-in shortening and butter were used to prepare croissants. The impact of the laminated dough matrix on fat crystallization was then investigated using powder X-ray diffraction (XRD), pulsed nuclear magnetic resonance (p-NMR) and differential scanning calorimetry (DSC). The fat contained within a croissant matrix has never before been analyzed using these techniques. In each case, XRD revealed that the polymorphism of a roll-in fat will be different when baked within the dough matrix than when simply heated and cooled on its own. Both hydrogenated roll-in shortenings and butter experienced only minor changes, largely retaining their β polymorphs, but the non-hydrogenated shortening experienced significant conversion from β to the β form. However, this conversion did not take place immediately upon cooling, but after approximately 24h of storage time. The fat contained within the croissants exhibited a significantly lower SFC than the same fats in bulk. Further, DSC results demonstrated that a greater temperature was required to completely melt all of the fat in a croissant than the same fat in bulk, observed visually as broader peaks in the melting endotherms. Analysis of croissant firmness over storage time, measured as the maximum force required to cut a croissant was used as an indication of potential sensory consequences. Results suggested that only croissants prepared with non-hydrogenated shortening experienced significant changes in firmness over one week of storage. These results indicate that there is an interaction between the shortenings and the ingredients of the croissant matrix, and given the differences observed between roll-in fats used, the extent of interaction is potentially influenced by the composition of the roll-in fat itself.

Engineering rheological properties of edible oleogels with ethylcellulose and lecithin

Addition of 1% (w/w) soy lecithin increased the shear moduli 10-fold and gel hardness 20-fold for 10% ethylcellulose (EC) oleogels. Higher lecithin addition levels or addition to gels with a higher EC concentration caused smaller increases. Similar trends were observed in the penetration force of the gels. Gels displayed thermal reversibility and a high temperature plateau at T≈120-130u2009°C. Large amplitude oscillatory shear rheology demonstrated similar solid-to-fluid transitions indicating that the polymer drives elastic softening and failure of the network. However, EC oleogels differed in their resistance to flow: the addition of unsaturated lecithin promoted a more gradual thickening response compared to gels containing saturated lecithin or only EC (the last two types of gels display strong intra-cycle thickening and thinning, more indicative of brittle failure). The thickening response of EC oleogels containing unsaturated lecithin, resembles more closely that of a model edible fat (lard).

Water immobilization by glass microspheres affects biological activity

We recently reported that the water holding capacity of myofibrillar protein hydrogels could be increased upon addition of small amounts of microparticles, particularly glass microspheres. Glass microspheres were found to decrease the spin-spin relaxation time (T2) of water protons in the gels, which was interpreted as enhanced water binding by the glass. We were thus interested in determining whether the observed effects on water proton relaxation were a direct consequence of water-glass interactions. Here we show how glass microspheres reduce the mobility of pure water, reflected in large decreases in the T2 of water protons, decreases in the self-diffusion coefficient of water molecules, a lower water activity, and strengthening of O-H bonds. Even though glass is considered an inert material, glass microspheres were shown to inhibit the growth of human embryonic kidney cells, and stimulate or inhibit the growth of leukemia and monocytic lymphoma cells in vitro, depending on dose and time. The germination of alfalfa seeds and the growth of E.coli cells were also inhibited upon exposure to glass microspheres. This work indicates that the properties and behavior of materials, even ones considered inert, can be affected by their size. These observations suggest possible toxicological consequences of exposure to microparticles, but also open us possibilities to affect cellular/organism function via modulation of macromolecular hydration.

Facile lipase-catalyzed synthesis of a chocolate fat mimetic

A cocoa butter equivalent (CBE) was synthesized enzymatically from readily available edible fats with fatty acid and triacylglycerol compositions that closely resemble the fat present in chocolate, cocoa butter. A commercially available immobilized fungal lipase, Lipozyme RM IM, was used as the reaction catalyst. Reaction parameters were a temperature of 65u2009°C, water activity of 0.11, a 4u2009h reaction time, and a substrate mass ratio of a commercial enzymatically synthesized shea stearin (SS) to palm mid-fraction (PMF) of 6:4 (w/w). Fractionation was also used after reaction completion to further approach the triacylglycerol composition of cocoa butter by removing trisaturated and unsaturated triacylglycerols. The yield of the triglyceride 1-palmitoyl-2-oleoyl, 3-stearoyl-glycerol (POS) produced was 57.7% (w/w). The amounts of 1,3-dipalmitoyl-2-oleoyl-glycerol (POP), (POS) and 1,3-stearoyl-2-oleoyl-glycerol (SOS) in the final CBE were 11.2%, 36.3%, and 34.8%, respectively. In comparison, the amounts of POP, POS and SOS in the cocoa butter used in this study were 15.2%, 38.2%, and 27.8%, respectively. No significant differences (Pu2009>u20090.05) in melting point and enthalpy of fusion between CB and the CBE were observed. In comparison, a non-interesterified blend of SS and PMF (60:40 w/w) showed significantly (Pu2009<u20090.05) higher melting point and lower enthalpy of fusion compared to CB. The crystal polymorphic form V of CB (β2-3L) was similar to that of CBE and SS/PMF (60:40 w/w). The solid fat content (SFC) vs. temperature profile of the CBE generally resembled that of CB, except that the CBE had significantly (Pu2009<u20090.05) higher SFCs at 5, 10, 15, 20 and 25u2009°C compared to both CB and SS/PMF (60:40 w/w). Addition of 15% (w/w) CBE to CB did not cause any changes in physical properties (melting point, SFC and crystal polymorphic forms) of the CB. This study demonstrates the potential for synthesizing a CB-like CBE using a green, rapid, straightforward one step enzymatic conversion followed by fractionation from widely available edible fats.

The fat in a perfect croissant

Delicious, flaky croissants owe their wonderful texture to the complex, multiscale structure of butter or related fats.

Molecular Insights into the Eutectic Tripalmitin/Tristearin Binary System

A molecular interpretation of the eutectic behavior of a binary mixture of tristearin (SSS) and tripalmitin (PPP) triglycerides was formulated using computer simulations and experimental techniques (calorimetry and X-ray scattering). A eutectic composition was identified using both experimental and computer simulation techniques at a composition of 70% PPP and 30% SSS, in agreement with previous findings in the literature. The decrease in the melting temperature at the eutectic composition can be ascribed to an interplay between enthalpic and entropic effects. In particular, a lower global melting enthalpy at the eutectic composition was detected here, caused by a less efficient packing of the triglycerides in the crystal. On the other hand, a higher crystalline disorder is reflected in a lower change in the entropy of melting. The simultaneous decrease in global enthalpy and entropy has a contrasting effect on the melting temperature, with a slight melting point depression found in both experiment and simulations, resulting from a combination of enthalpic and entropic factors. Computer simulations showed, in fact, that the eutectic effect can be ascribed to the reduction of crystalline order when SSS molecules are incorporated into the PPP crystal structure. This decrease of the crystalline order is due to the protrusion of SSS end-chains (last three carbons of each alkyl chain) into the interlamellar space between adjacent lamella. These end-chains disturb the orderly stacking of the lamella, as evidenced by low-density regions in the interlamellar space. Thus, the greater disorder of the last atoms of the SSS alkyl chains is consequently due to the greater conformational freedom. At molecular level, in fact, the conformational freedom of terminal atoms of SSS surrounded by shorter PPP molecules is larger than the conformational freedom of longer SSS in the neighborhood of short PPP.

Monitoring the Polymorphic Transformation of a Palm Kernel-Based Emulsion Using Ultrasound

Ultrasonic spectrometry was used to monitor the changes in polymorphism of palm kernel fat present in two tempered non-dairy emulsions with different globule sizes. Laser diffraction and differential scanning calorimetry (DSC) were performed to characterize the emulsions. X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) were used to determine the polymorphic state and solid fat content (SFC) of fully hydrogenated palm kernel oil during tempering of the emulsions. The ultrasonic instrument generated a “chirp” signal, which is characterized by its bandwidth. The ultrasonic measurements were carried out using two different pairs of transducers with different center frequencies, 2.25 and 0.5xa0MHz, and bandwidths. 3D plots were generated disputing time, frequency, and signal strength. The whole tempering process, from start to finish, was better characterized with the 2.25-MHz center frequency transducers. The ultrasonic velocity through the emulsions was always higher for the more stable β′ polymorph than for the α polymorph (pu2009<u20090.05) regardless of the pair of transducers used. The 2.25-MHz transducer revealed no significant difference (pu2009>u20090.05) on the ultrasound velocities obtained for the two globule sizes. Monitoring of polymorphic changes in emulsions using ultrasonic spectrometry could be used for an online measurement system for industrial manufacturing.