Unraveling the role of probiotics in affecting the structure of monoglyceride gelled emulsions: A low-field 1H NMR study.

The capacity of monoglyceride (MG) gelled emulsions (MEs) in protecting probiotic cells of Lacticaseibacillus rhamnosus against stresses suffered during food processing, storage, and human digestion has been recently demonstrated. These findings open new perspectives on the possible participation of probiotics in the stabilization of emulsion structure. To unravel this aspect, rheological analysis and Low-Field 1H NMR investigations were performed on MEs having different aqueous phases (water or skimmed milk) and stored for increasing time (1 and 14 days) at 4 °C. Loaded and unloaded samples were considered. Results highlighted that probiotics initially hindered the ability of MG to self-assemble in the multiphase environment, interacting in some way with MG crystalline lamellar structure, as confirmed by rheological and 1H NMR analysis. During storage, an increase of proton compartmentation was observed in loaded MEs indicating the role of probiotics in stabilizing MG structure at a molecular level. Such a result was more evident when the system was composed of milk, suggesting that the presence of milk-native components (i.e., lactose, proteins, and minerals) favored the cell-structure interactions. Such preliminary results could open new perspectives in considering probiotic cells as having an active role in the stabilization of food structure.

Effect of moderate hydrostatic pressure on crystallization of palm kernel stearin-sunflower oil model systems.

Lipid crystallization under moderate hydrostatic pressure treatments (200 MPa, 20 °C, 1-24 h) was studied in palm kernel stearin (PS 100%) and its blends with sunflower oil (PS 80, 90 % w/w). Hyperbarically-crystallized samples exhibited significantly higher firmness, elastic modulus and critical stress values as compared to those of the samples crystallized at atmospheric pressure. These data indicate that moderate hydrostatic pressure favored the formation of a higher amount of small palm kernel stearin crystals as compared to those formed at atmospheric pressure. Pressurization did not affect fat polymorphism, but was able to enhance nucleation instead of crystal growth. This work clearly demonstrated the efficacy of moderate hydrostatic pressure in steering lipid crystallization, opening interesting possible applications of high-pressure processing technology in the fat manufacturing sector.

Oleogelation of extra virgin olive oil by different gelators affects lipid digestion and polyphenol bioaccessibility.

The possibility to steer extra virgin olive oil (EVOO) digestion and polyphenol bioaccessibility through oleogelation was investigated. EVOO was converted into oleogels using lipophilic (monoglycerides, rice wax, sunflower wax, phytosterols) or hydrophilic (whey protein aerogel particles, WP) gelators. In-vitro digestion demonstrated that the oleogelator nature influenced both lipid digestion and polyphenol bioaccessibility. WP-based oleogels presented ∼100% free fatty acid release compared to ∼64% for unstructured EVOO and ∼40 to ∼55% for lipophilic-based oleogels. This behavior was attributed to the ability of WP to promote micelle formation through oleogel destructuring. Contrarily, the lower lipolysis of EVOO gelled with lipophilic gelators compared to unstructured EVOO suggested that the gelator obstructed lipase accessibility. Tyrosol and hydroxytyrosol bioaccessibility increased for WP oleogels (∼27%), while liposoluble-based oleogels reduced it by 7 to 13%. These findings highlight the deep effect of the gelator choice on the digestion fate of EVOO components in the human body.

Design and advanced characterization of quercetin-loaded nano-liposomes prepared by high-pressure homogenization.

Quercetin-loaded nano-liposomes were prepared by high-pressure homogenization (HPH) at different pressures (up to 150 MPa) and number of passes (up to 3) to define the best processing conditions allowing the lowest particle size and the highest encapsulation efficiency (EE). The process at 150 MPa for 1 pass was the best, producing quercetin-loaded liposomes with the lowest particle size and 42% EE. Advanced techniques (multi-detector asymmetrical-flow field flow fractionation and analytical ultracentrifugation combined with transmission electron microscopy) were further used for the characterization of the liposomes which were oblong in shape (ca. 30 nm). Results highlight the need for several techniques to study nano-sized, polydisperse samples. The potential of quercetin-loaded liposomes against colon cancer cells was demonstrated. Results prove that HPH is an efficient and sustainable method for liposome preparation and highlight the remarkable role of process optimisation as well as the powerfulness of advanced methodologies for the characterisation of nano-structures.

Role of the polyphenol content on the structuring behavior of liposoluble gelators in extra virgin olive oil.

The role of polyphenols in affecting the structural and rheological properties of oleogels was investigated. Polyphenols were selectively removed from extra virgin olive oil (EVOO), and the resulting oils at three different polyphenol levels were gelled by using 10% (w/w) of monoglycerides (MG), rice wax (RW), sunflower wax (SW), and a mixture of ß-sitosterol/γ-oryzanol (PS). The structural characteristics of oleogels were assessed by visual appearance, rheology, polarized light microscopy, calorimetry, XRD, and FTIR. Polyphenol content differently affected oleogel characteristics depending on network features. While EVOO-polyphenols did not influence PS- and SW-based oleogels, they reinforced MG- and RW-based oleogel network. As polyphenol content increased, the critical stress and melting temperature also increased, concomitantly with changes in crystal morphology. This was attributed to the capacity of polyphenols to form additional junction points in the crystalline network.

Comparison of protein in vitro digestibility under adult and elderly conditions: The case study of wheat, pea, rice, and whey proteins.

In this study an in vitro static digestion method mimicking the elderly gastrointestinal conditions was designed by adapting the physiological parameters described in the INFOGEST standardized static in vitro digestion protocol, i.e., pH, digestive phase duration, concentrations of enzymes and bile salts, to the aged GI transit. The digestibility of proteins from different sources (pea, rice, wheat, and milk whey) was then assessed. Protein digestive behaviour was monitored after gastric and intestinal phases by BCA assay and SDS-PAGE to assess protein hydrolysis both from a quantitative and a qualitative point of view. Digested samples were also analysed for physical characteristics in terms of particle size and zeta potential. Data acquired under elderly gastrointestinal conditions were compared to those obtained by using the INFOGEST protocol designed to study adult digestion. Results clearly showed that the elderly gastrointestinal conditions deeply affected proteolysis leading to a general reduction of protein digestibility in comparison to the adult model. The proteolysis extent depended on the protein source with whey and rice proteins showing about 20% reduction using the model mimicking the elderly gut, followed by pea (about 10% reduction) and wheat (about 4% reduction) proteins. The knowledge of protein digestibility under elderly gastrointestinal conditions generated in this study could be useful in the attempt to develop age-tailored products.

Steering protein and lipid digestibility by oleogelation with protein aerogels.

The aim of the present work was to assess the effect of an innovative oleogelation strategy, the aerogel-template approach, on protein and lipid digestibility. Whey protein isolate (WP) was converted into aerogel particles via supercritical CO2 drying. Oleogels were then prepared by absorption of sunflower (SO) or flaxseed (FLX) oil (80%, w/w) into the aerogel particle template and subjected to in vitro digestion. WP aerogel-templated oleogels showed a specific destructuring behaviour during digestion. Confocal micrographs clearly demonstrated that the original oleogel structure was lost at the gastric level, with the release of oil droplets smaller (D32 < 10 µm) than those observed in the case of the unstructured oils (D32 > 30 µm), stabilised by undigested aerogel proteins. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and bicinchoninic acid (BCA) assay confirmed that aerogelation reduced the gastric proteolysis of WP from nearly 100% to 70%. The digestion of the SO oleogel led to similar gastric protein digestibility. In contrast, in the case of the FLX oleogel, gastric proteolysis decreased to 40%, suggesting a role of the oil nature in steering WP aerogel digestion. In all cases, upon intestinal digestion aerogel proteins resulted completely hydrolysed. The lipolysis degree of SO (75%) and FLX (34%) oil in the oleogels was higher than that of the unstructured SO (66%) and FLX (24%) oils, due to the larger surface offered by smaller oil droplets to the action of intestinal lipases. This was confirmed by dynamic light scattering, showing a shift towards smaller size in the digestive micelle distribution of oleogels at the end of the intestinal phase. Oleogelation through the WP aerogel-template approach could be regarded as a strategy to steer lipid digestibility while also modulating the release of bioaccessible peptides.

Designing food for the elderly: the critical impact of food structure.

Ageing is an unavoidable progressive process causing many changes of the individual life. However, if faced in an efficient way, living longer in a healthy status could be an opportunity for all. In this context, food consumption and dietary patterns are pivotal factors in promoting active and healthy ageing. The development of food products tailored for the specific needs of the elderly might favour the fulfilment of nutritionally balanced diets, while reducing the consequences of malnutrition. To this aim, the application of a food structure design approach could be particularly profitable, being food structure responsible to the final functionalities of food products. In this narrative review, the physiological changes associated to food consumption occurring during ageing were firstly discussed. Then, the focus shifted to the possible role of food structure in delivering target functionalities, considering food acceptability, digestion of the nutrients, bioactive molecules and probiotic bacteria.

Oleogelation of extra virgin olive oil by different oleogelators affects the physical properties and the stability of bioactive compounds.

Extra virgin olive oil (EVOO) was gelled with 10% monoglycerides, (MG), rice wax (RW), γ-oryzanol, and ß-sitosterol (PS), or ethylcellulose (EC). The oleogel structure and the stability of bioactive compounds were investigated during storage up to 120 days at 20, 30, and 40 °C. All samples were self-standing but presented different structures. PS produced the firmest gel, whereas EC caused the lowest firmness and rheological values. Structural properties did not change during storage, except for EC oleogel. Structuring triggered a depletion in phenolic content and α-tocopherol, which was more pronounced when a higher temperature was required for oleogel preparation (MG ~ RW < PS < EC). However, during storage phenolics and α-tocopherol decreased following zero-order kinetics with a higher susceptibility in unstructured oil, suggesting in all cases a protective effect of the gel network.

Conversion of Whey Protein Aerogel Particles into Oleogels: Effect of Oil Type on Structural Features.

Protein aerogel particles prepared by supercritical-CO2-drying (SCD) of ground whey protein (WP) hydrogels (20% w/w, pH 5.7) were converted into oleogels by dispersion in selected edible oils (castor, cod liver, corn, flaxseed, MCT, peanut and sunflower oil). The obtained oleogels were analysed for oil content, microstructure, rheological properties, and ATR-FTIR spectra. Except for castor oil, solid-like, plastic materials with comparable composition (80% oil, 20% WP) and rheological properties (G'~3.5 × 105 Pa, G″~0.20 × 105 Pa, critical stress~800 Pa, tanδ~0.060) were obtained. Optical and confocal microscopy showed that the generated structure was associated with the capillary-driven absorption of oil into the porous aerogel particles interconnected via particle-particle interactions. In this structure, the oil was stably entrapped. Results evidenced the reduced role of edible oil characteristics with the exception of castor oil, whose high polarity probably favoured particle-oil interactions hindering particle networking. This work demonstrates that WP aerogels could be regarded as versatile oleogel templates allowing the structuring of many edible oils into solid-like materials.

Effect of a yeast autolysate produced by high pressure homogenization on white wine evolution during ageing.

The enological characteristics and the performances of a yeast autolysate produced by high pressure homogenization (HPH-YD) were investigated for the first time in white wine and model solution, in comparison with a thermolysate (T-YD) and a commercial yeast derivative (COMM). In wine-like medium, HPH-YD showed a significant release of glucidic colloids (on average, slightly higher than the other products), also leading to a greater glutathione solubilization with respect to T-YD. Concerning the volatile composition of the autolysates, HPH-YD was characterized by the highest concentration of alcohols and esters, while showing an average amount of fatty acids, carbonyls and heterocyclic compounds lower than COMM. These features are potentially linked to a more favorable impact of this product on the composition of wine aroma, should these compounds be released into the wine itself. HPH-YD determined minor modifications on wine volatile profile when added for short contact times, without releasing unwanted compounds and with a slightly lower binding capacity towards wine esters. The effects of the three yeast derivatives (YDs) on wine color during ageing was also investigated in comparison with sulfur dioxide (SO2). HPH-YD was the most efficient preparation, limiting wine color changes due to oxidation during four months and behaving more similarly to SO2. The use of HPH for the production of yeast autolysates for winemaking may represent an interesting alternative to thermal treatments, improving the enological characteristics of these additives, particularly their antioxidant capacity, leading anyhow a significant release of colloidal molecules and a limited impact on wine aroma composition.

Study on the possibility of developing food-grade hydrophobic bio-aerogels by using an oleogel template approach.

The feasibility of producing food-grade hydrophobic bio-aerogels by supercritical-carbon dioxide (SC-CO2) extraction of oil from oleogels was investigated for the first time. Medium chain triglycerides (MCT) oil was gelled using ethylcellulose (EC) at increasing concentration (10, 15, 20% w/w) and grade (EC20, 45, 100), eventually in combination with fillers. Different SC-CO2 oil extraction procedures were tested. The acquired results show that both oleogel formulation and extraction conditions can steer the EC scaffold structure. The increase in EC concentration and grade resulted in oleogels more structurally stable to SC-CO2 extraction. The application of a pulsed extraction procedure allowed obtaining a low-density (0.39 â€‹g/cm3) EC scaffold presenting 60% oil. Addition of freeze dried lettuce powder improved macrostructure homogeneity. The obtained results lay the foundations for developing food-grade hydrophobic bio-aerogels, which are expected to present unique oil absorption and bioactive delivery features.

Correction: Effect of the formulation and structure of monoglyceride-based gels on the viability of probiotic Lactobacillus rhamnosus upon in vitro digestion.

Correction for 'Effect of the formulation and structure of monoglyceride-based gels on the viability of probiotic Lactobacillus rhamnosus upon in vitro digestion' by Sofia Melchior et al., Food Funct., 2021, DOI: 10.1039/D0FO01788D.

Application of high-pressure homogenization to tailor the functionalities of native wheat starch.

BACKGROUND: The effect of high-pressure homogenization (HPH) on the rheological and thermal properties, water retention capacity (WRC), morphology and in vitro digestion of wheat starch was evaluated. Starch suspensions (50 g kg-1 , w/w) were treated at increasing pressures (up to 100 MPa) and numbers of cycles (up to 5) to generate a wide range of energy densities (70-500 MJ m-3 ) delivered to the sample during processing. RESULTS: High-pressure homogenization induced a partial starch gelatinization confirmed by higher digestibility. Gelatinization degree (GD) was between 13% and 83%, causing a wide range of functional properties. High-pressure homogenization-treated starch samples showed WRC values of 810-1910 g kg-1 . Storage modulus (G') and complex viscosity (η* ) of starch dispersions were almost two and three times higher than the control at 13% and 83% GD, respectively. Positive linear relationships between GD (R = 0.98, P < 0.001), WRC (R = 0.87, P < 0.05), or rheological parameters (R = 0.89÷0.90, P < 0.01) and energy density of HPH treatments were found. CONCLUSION: High-pressure homogenization treatment represents a promising technology to obtain wheat starch with tailored rheological properties and digestibility, which allows the texture and glycemic response of food products to be adjusted. © 2020 Society of Chemical Industry.

Effect of the formulation and structure of monoglyceride-based gels on the viability of probiotic Lactobacillus rhamnosus upon in vitro digestion.

This research was conducted to evaluate the potential use of saturated monoglyceride (MG)-based gels in the protection of probiotics upon in vitro digestion. For this purpose, a Lactobacillus rhamnosus strain was inoculated into binary and ternary systems, containing MGs, a water phase composed of an aqueous solution at controlled pH or UHT skimmed milk, and in ternary gels, sunflower oil. Gel structure characterization was initially performed just after preparation and after 14 days of storage at 4 °C by rheological, mechanical, thermal, and microscopy analyses. Afterwards, probiotic viability upon in vitro digestion was evaluated. The results highlighted that all freshly prepared samples showed good capability to protect L. rhamnosus with the exception of the binary system containing milk. However, the digestion of samples after 14 days of storage showed that the ternary system containing skimmed milk exhibited the best protection performance ensuring a L. rhamnosus viability of almost 106 CFU g-1 at the end of the gastrointestinal passage. Confocal microscopy results demonstrated that bacterial cells were located prevalently within the aqueous domain near the monoglycerides and protein aggregates. Under these conditions, they can simultaneously achieve physical protection and find nutrients to survive environmental stresses. These findings suggest that MG-based gels can be proposed as efficient carriers of probiotic bacteria not only during food processing and storage but also upon digestion.

Exploring the Potentialities of Photoinduced Glycation to Steer Protein Functionalities: The Study Case of Freeze-Dried Egg White Proteins/Carbohydrates Mixtures.

The capacity of UV-C light to induce glycation and modify functional properties of systems containing freeze-dried egg white proteins and carbohydrates with increasing molecular weight (i.e., glucose, maltose, trehalose and maltodextrin) was studied. Color changes induced by light exposure were taken as typical indicators of glycation. Samples were then analyzed for selected physical (critical concentration, particle size and viscosity), chemical (ovalbumin content) and technofunctional properties (gelling temperature and foaming capacity). The presence of sugars during exposure to UV-C light promoted intense browning and decreased ovalbumin content by circa 30%. Concomitantly, up to a 3-fold increase in critical concentration of the aqueous suspensions of the irradiated protein-carbohydrate powders and changes in particle size were detected. These modifications were consistent with the development of non-enzymatic browning reactions upon UV-C light irradiation. Photoinduced glycation was associated to a decrease in viscosity, a tendency to form gel at temperature lower by up to 8 °C and a better capacity of foam stabilization. The intensity of these changes seems to be affected by the nature of the carbohydrates reacting with proteins, with longer carbohydrates able to produce systems with higher foam stability capacity.

Modeling the Effect of the Oxidation Status of the Ingredient Oil on Stability and Shelf Life of Low-Moisture Bakery Products: The Case Study of Crackers.

In packed low-moisture foods such as crackers, oxidation is generally the main cause of quality depletion during storage. It is commonly believed, but scarcely investigated, that product shelf life depends on the oxidative status of the lipid ingredients. In this study, the influence of oxidation degree of the ingredient sunflower oil on cracker oxidative stability and hence shelf life was investigated. To this aim, oil with increasing peroxide values (PVs) (5, 11, and 25 mEqO2/kgoil) was used to prepare crackers. Just after production, crackers presented similar peroxide and rancid odor intensity, probably due to the interactive pathways of oxidative and Maillard reactions. Crackers were packed and analyzed for PV and rancid odor during storage at 20, 40, and 60 °C. Rancid odor well discriminated cracker oxidative status. Relevant oxidation rates were used to develop a shelf life predictive model based on the peroxide value of the ingredient oil. It was estimated that an oil PV from 5 to 15 mEqO2/kgoil shortens cracker Shelf Life (SL) by 50%, independently of storage temperature. These results demonstrate the critical impact of ingredient quality on product performance on the market.

Effect of different biopolymer-based structured systems on the survival of probiotic strains during storage and in vitro digestion.

BACKGROUND: This study aimed to evaluate the protective effect of different biopolymer systems on the viability of two probiotics (Lactobacillus rhamnosus and Streptococcus thermophilus) during storage and in vitro digestion. Methylcellulose (MC), sodium alginate (SA), and whey protein (WP)-based structures were designed and characterized in terms of pH, rheological properties, and visual appearance. RESULTS: The results highlighted that the WP-system ensured probiotic protection during both storage and in vitro digestion. This result was attributed to a combined effect of the physical barrier offered by the protein gel network and whey proteins as a nutrient for microbes. On the other hand, surprisingly, the viscous methylcellulose-based system was able to guarantee good microbial viability during storage. However, this was not confirmed during in vitro digestion. The opposite results were obtained for sodium alginate beads. CONCLUSION: The results suggest that the capacity of a polymeric structure to protect probiotic bacteria is a combination of structural organization and system formulation. © 2020 Society of Chemical Industry.

Temperature Dependence of Oxidation Kinetics of Extra Virgin Olive Oil (EVOO) and Shelf-Life Prediction.

Producers have to guarantee the extra virgin olive oil (EVOO) quality characteristics reported in the Regulation (CEE) 2568/91 throughout the product shelf-life (SL). Unfortunately, due to the development of oxidative reactions, some quality indices change during storage leading to a progressive deterioration of EVOO quality. To avoid the risk of product downgrading in the virgin oil category, the development of effective shelf-life prediction models is extremely important for the olive oil industry. In this research, the accelerated shelf-life testing (ASLT) protocol was applied to evaluate the temperature dependence of selected oxidation indexes as well as to develop a shelf-life predictive model. The evolution of conventional (peroxide value, K232, K270, polyphenols, tocopherols and hexanal) and unconventional parameters (conjugated trienes and pyropheophytin a) was monitored in bottled EVOO stored in the dark at increasing temperature (25, 40, 50 and 60 °C). Accordingly, for well-packed products with reduced oxygen in headspace, the best shelf-life index allowing the ability to predict EVOO SL turned out to be K270. In addition, pyropheophytin a (%) has been shown to be more sensitive to temperature changes than the secondary oxidation indices, thus suggesting its use as a freshness indicator for storage temperatures higher than 25 °C.

Effect of different oleogelators on lipolysis and curcuminoid bioaccessibility upon in vitro digestion of sunflower oil oleogels.

Sunflower oil enriched with curcuminoid compounds (CUs) was gelled by adding 5% (w/w) saturated monoglycerides (MG), rice bran waxes (RW) or a mixture of ß-sitosterol and γ-oryzanol (PS). The resulting oleogels differed for rheological properties and firmness due to the difference in gel network structure. PS oleogel was the firmest sample followed by RW and MG ones. Upon in vitro digestion, fatty acid release as a function of digestion time was greatly affected by oleogel structure: the extent of lipolysis decreased as oleogel strength increased (PS < RW < MG). On the other hand, the nature of the oleogelator affected CUs bioaccessibility, which was lower in oleogels containing crystalline particles (MG and RW). These findings appear interesting in the attempt to develop oleogels able to control lipid digestion as well as to deliver bioactive molecules in food systems.