We investigated the development of water-in-oil (W/O) emulsions just using CW, evaluating the effect of the water to CW oleogel ratio (40:60, 50:50, 60:40) and, at each ratio, the effect of the CW concentrations (0.75% to 3%). The emulsions were developed by shearing (60 s at 25°C) using an ultra-turrax type homogenizer. The emulsions were immediately evaluated and after 20 days of storage (25°C) for microstructure, water droplet diameter, emulsion stability through DSC freeze/thaw cycles, rheological properties, and X-ray measurements. The results showed that, at all water to oleogel ratios studied the CW developed structured W/O emulsions where the surface-active components of the CW (i.e., triterpenic alcohols, aliphatic alcohols, and fatty acids) stabilized the oil-water interface, while the n-alkanes and long chain esters formed an oleogel in the oil phase. Although, independent of the storage time, all the CW emulsions showed a frequency independent rheological behavior, after applying a strain above the G’-G” cross point, the 40:60 and 50:50 emulsions with 1.5% to 3% CW concentration showed the better rheological behavior and were the most stables, even after two freeze-thaw cycles. In particular, the 40:60 and 50:50 emulsion with 1.5% CW had a recovery profile similar to commercial mayonnaise. In contrast, independent of the CW concentration, the 60:40 emulsions showed the lowest recovery profiles and higher instability to freeze-thaw cycles. These results indicated that the CW is a multi-functional material able to develop structured W/O emulsions useful for the formulation of trans-free, stable low-fat edible spreads.
Oleoresins are resin-like viscous materials obtained from plants, oilseed, or spices with functional properties. The extraction process determines their stability, composition, and physicochemical properties. Oleoresins were obtained from ground waxy burgundy whole grain sorghum with and without ball milling by using the following solvents: two types of novel ionic liquids (IL1: 1-n-Hexyl-3-methylimidazoliumchloride, IL2: 1-Ethyl-3-methylimidazoliumchloride), ethanol and dichloromethane. The effects of processing were evaluated for the extraction yield, protein, fat and total phenolic content, fatty acid composition, particle size and zeta potential, and FTIR spectra. The use of ILs and ball mill process significantly (P < 0.05) affected the extraction yield and physicochemical properties. The highest extraction yields increased (31.35% ± 0.58) when ball milling used with IL2 in comparison to the lowest (18.37% ± 0.77) obtained by traditional ethanol extraction. In a similar way, protein concentration and phenolic content were the highest (1.37% ± 0.05 and 0.57% ± 0.01, respectively) with ball milling extraction and IL1. The FTIR spectra indicated higher phospholipids (at 1200 cm-1) and protein-phospholipid bonding (at 1700 cm-1) by ILs, and ball milling as compared to traditional extraction. Overall, wet milling-assisted extraction by using ball mill and ILs can provide control for the composition of the oleoresins important for their functional properties with higher extraction efficiencies as compared to traditional techniques.
This study investigated an alternative approach to valorizing canola proteins by hydrolyzing them to generate amino acids (AAs). Pre-treatment of cold-pressed (CP) cake and desolventized-toasted (DT) meal with ethanol (99%, v/v) followed by protein separation was studied as process optimizations to maximize protein recovery with higher purity. The optimum ethanol pre-treatment conditions to achieve a meal containing less than 1% oil was reached at a meal-to-ethanol ratio of 1:4 (w:w) and 50°C for 30 min extraction. The protein recovery reached the maximum at pH 12 and a meal-to-solvent ratio of 1:10 (w:v), yielding 73% and 33% recovery from ethanol pre-treated CP and DT meals, respectively, in a single extraction. Untreated and ethanol pre-treated meals were hydrolyzed with 6 M HCl (protein-to-acid ratio of 5 mg:2 mL) for 24 h at 110°C. The ethanol pre-treatment improved AA recovery and released 373 mg AA/g dry CP meal biomass (dbm) compared to 279 mg AA/g untreated CP cake dbm. However, no improvement in AA recovery upon ethanol pre-treatment of DT meal. H2SO4 was examined as an alternative acid. More than 80% of the total AAs of CP proteins were released with 3 M H2SO4, while for DT meal proteins, a 5 M concentration was needed to achieve the same. Commercial canola meals can be utilized for generating free AAs; however, the meal processing history may affect the yield.
Three oleogeletors molecules (Triacontane (TC), Stearic acid (SA), and Behenyl Lignocerate (BL)) were studied individually, in pairs, or all together to make an oleogel using triolein as the oil. WAXS, SAXS and USAXS were used to elucidate the solid structures from angstroms to a few micrometers. A two-dimensional mapping of atomic positions for each molecule was carried out to understand the crystalline multilayer structures formed. We assumed that the molecules were rigidly extended and that they underwent no significant (hindered) rotations so that the free energy is determined by the Lennard-Jones interactions of closely-packed multilayers. TC molecules were predicted to form a tilt angle of θt ≈ 33°, yielding a SAXS line at q≈ 0.194 Å-1, in acceptable agreement with the measured q=0.181 Å-1.For SA crystals θt ≈ 33° (predicted) yielding a SAXS line at q=0.150 Å-1 compared to q=0.159 Å -1 (observed). No mixed crystals were observed for any pair of molecules or when all three were used. USAXS data showed that SA forms large nanocrystals compared to TC and BL. All three combinations of molecular pairs showed basic scatterers smaller or similar to those of individual molecules. The theory presented here, together with the experimental results, showed why no mixed crystals are formed from two or all three molecules. Data from the USAXS region suggested that, when using all three molecules, a more compact fractal structure was obtained, compared with those if one or two of the molecules were used.
Vegetable fats are complex multi-component mixtures of triglycerides. Here, the solidification behavior of a few vegetable fats is calculated using the Hildebrand equation. This calculation assumes, in the liquid phase, ideal mixing of the different components, in combination with literature data about the temperatures and enthalpies of fusion of the individual triglycerides. It further assumes a decomposition of the triglyceride blend into binary blends dissolved in an inert solvent. The solid fat content is calculated as function of the temperature, assuming that all triglycerides solidify in a single crystal habit (all α or all β or all β’). The minor triglyceride components are explicitly taken into account. The calculated solid fat contents for cocoa butter, palm oil, inter-esterified palm oil and palm kernel olein oil are compared to pNMR data, reported in the literature. Temperature ranges are found, in which specific crystal modifications match to the pNMR data for the solid fat content. These temperature ranges are found to be consistent with literature data obtained using X-ray diffraction. As a by-product, the calculation presented here, enables the construction of scenarios that describe which triglyceride solidifies in which temperature interval.
Plant-based high internal phase oil-in-water emulsions (HIPEs) are promising fat replacers. However, producing stable HIPES with improved viscoelastic properties is a challenge for the food industry. Conjugation of plant proteins, such as lupin protein isolate, with phenolic compounds, such as proanthocyanidins from grape seed extract, associated (or not) with moderate heat treatment arise as potential methods to tune the surface properties of proteins and, consequently, the droplet-droplet interactions that drive the viscoelastic properties of HIPEs. In this way, unheated (UHC) and heated (85°C, 15 min) (HC) lupin protein (LPI)-grape seed extract (GSE) conjugates were produced and used to stabilize high internal phase oil-in-water emulsions. Evaluation of stability by Turbiscan and oil loss by centrifugation over 56 days of storage did not reflect the kinetic stability of HIPEs against process conditions. Under shearing, UHC-stabilized emulsions at high GSE concentrations showed oil release, whereas all HC-stabilized HIPEs released oil. However, the increase in GSE concentration and heat treatment improved the viscosity and storage modulus (G’) of HIPEs, possibly due to the droplet-droplet interaction originating from hydrophilic and hydrophobic interactions in UHC and HC-stabilized HIPEs, respectively. This pivotal study confirmed that conjugation of a plant protein with GSE and heat treatment could improve the viscoelastic properties of high internal phase oil-in-water emulsions and produce HIPEs with superior texture (higher G’).
To date no single gas chromatographic method can simultaneously measure all fatty acids (FA), including trans FA (TFA), that are contained in dairy products, partially hydrogenated oils (PHO), and refined vegetable oils. Using 100% poly(biscyanopropyl siloxane) capillary columns, ruminant and dairy fats are preferentially analyzed by applying temperature programs that separate short chain FA, but not trans-18:3 from 20:1. Refined vegetable oils and PHO are preferentially analyzed by applying isothermal elutions that provide quantification of all 18 carbon TFA including trans-18:3 FA, but not of all short chain FA. In this short communication, we propose a temperature program method capable of simultaneously measuring short chain FA and all 18 carbon TFA including trans-18:3 by applying a negative temperature gradient after the elution of trans-18:1. A simplified version of the method is also described for equipment not able to perform negative temperature gradients.
In this study, the effects of solid-state fermentation (SSF), including strain (Aspergillus niger NRRL 334 and A. oryzae NRRL 5590) and fermentation time (24, 48, and 72 h) on the nutritional value of cold-pressed (CP) and hexane-extracted (HE) canola meals were examined. SSF increased the protein content of both types of meals (from ~36 to ~40%) while reducing the oil content of CP meals (from ~12 to 9%). There was a significant reduction (~80%) in the phytic acid content of both types of meals after fermentation using either fungi. Overall, fermented samples showed a decrease in the total phenolic content from 2.7-3.1 to ~1.0 mg gallic acid equivalents (GAE)/g DM (a ~65% reduction), of which specifically the HE meal fermented with A. niger sample had the greatest decrease from 3.1 to 0.6 mg GAE/g DM (~81% reduction). Seventy-two hours of fermentation decreased the in vitro protein digestibility (IVPD) of the meals. In contrast, a shorter fermentation time (24 h) increased the IVPD as compared to the controls (from ~73% to 77-81%), with the exception of the CP meal fermented with A. niger which had decreased IVPD at all fermentation times. Overall, the changes indicate that SSF using A. niger or A. oryzae can be useful to positively modify the composition of different canola meals and improve their nutritional value by significantly increasing the protein content, decreasing the levels of antinutrients, while only slightly reducing IVPD.
There are more and more studies on the detection method of 3-chloro-1,2-propanediol fatty acid esters (3-MCPD esters) at present. By comparing these methods for the determination of 3-MCPD esters. Indirect methods, which determine total amount of 3-MCPD after hydrolysis of the esters, have an advantage over direct methods. The existing indirect methods, however, may yield unreliable results or require long hours of alkaline methanolysis. In contrast, the Indirect enzymatic hydrolysis method has mild conditions and more accurate results. In this study, we developed a reliable and rapid indirect method for determinations of 3-MCPD esters. 3-MCPD esters was enzymatized to 3-MCPD by indirect enzymatic hydrolysis method, and the conditions of enzymatic hydrolysis were optimized, the content of 3-MCPD after enzymatic hydrolysis was detected by gas chromatography-mass spectrometry (GC-MS) and the yield was calculated. Finally, the optimum conditions for enzymatic hydrolysis of 3-MCPD esters were determined. According to the optimal enzymatic hydrolysis condition, the contents of 3-MCPD esters in four food oils were determined. The method is simple and sensitive, and can meet the requirement of 3-MCPD esters detection in general oils.
Oxidative polymerization of plant oils and lipids is poorly understood yet widely encountered. Oil oxidation is accelerated at high temperatures, typically above 110°C, where tri-acylglycerides are converted into toxic compounds and viscous deleterious polymers. Polymerization of mono-unsaturated oil (210°C, 3h, open to air) was investigated by comparing four similar sized molecules with different functional groups: oleic acid, methyl oleate, trans-7-tetradecene and stearic acid. Non-volatile products identified by NMR spectroscopy are minor ketones for saturated fatty acid (stearic acid), epoxides for acyl chains without acid groups (methyl oleate, tetradecane) and copious oligomerization, through ester cross-links, for acyl chains with acid and olefinic groups (oleic acid). Long range C-H coupling clearly shows ester (not ether) cross-links, contradicting long held beliefs. Chain fragmentation also occurs as revealed by species with methylene groups bonded to oxygen, -CH2-O-C(=O)-R. Large size (slow diffusion) of the first oligomer (trimer) formed by thermal oxidation of oleic acid, (representing hydrolyzed vegetable oil) was evidenced by DOSY (diffusion ordered spectroscopy). Since the first oligomers formed still have reactive groups (olefin, carboxylic acid), poly-ester formation is inevitable at longer oxidation times. Model oil reactions monitored by NMR spectroscopy are important for resolving the complex chemistry of vegetable oil polymerization.
The present study investigated the effect of solid-state fermentation (SSF) of cold-pressed (CP) and hexane-extracted (HE) canola meals with Aspergillus niger NRRL 334 and A. oryzae NRRL 5590 on the functionalities of protein products extracted from them. After SSF, proteins were recovered using alkaline extraction-isoelectric precipitation (AE-IP) or salt extraction-dialysis (SE). SSF of the two meal types reduced the protein content of the extracts produced by AE-IP. There were varied effects to solubility, foaming, and emulsifying properties as a result of SSF under the combined influence of functionality pH, strain, meal type, and protein extraction method. The protein isolate produced from CP meal using SE had increased solubility at pH 7 (from 51.8 to 90.7%) when the meal was fermented with A. oryzae. Both strains resulted in an over 2-fold increase in the emulsifying activity index (at pH 7) of AE-IP products from CP meal. For both protein extraction methods, the protein products from A. niger fermented HE meal had better foaming capacity (FC) at pH 7 than the controls (non-fermented), but reduced FC at pH 3. Overall, regardless of meal fermentation, the SE products were richer in protein and had higher oil holding capacity (OHC), whereas the water holding capacity (WHC) was higher for AE-IP isolates. SSF of the meals generally improved the O/WHC of the extracted proteins. The findings suggest that canola protein functionality could be effectively modulated by SSF with different microbial strains under various processing conditions to enhance their applicability in the food industry.
The extraction of butter from cocoa seeds involves various processing steps that weak the lipid-storing cell walls of cocoa cotyledons. Roasting is particularly critical, making cocoa nibs porous and brittle. In this study, the degree of disruption of the microstructure of cocoa nibs, and the quality and aroma profile of cocoa butter, were evaluated using two roasting techniques, forced convective oven, and fluidized bed. Fluidized bed roasting, recognized for its energy efficiency and low-footprint synthesis, was more than 10 times faster than oven roasting. This technique allowed a fast release of steam when parenchyma cell walls were still in a glassy state, while oven roasting caused gradual physical modification allowing the cell wall to become more elastic. Consequently, when using fluidizing bed technique, small pores of unroasted cocoa nibs swelled and coalesced to produce more large-sized ones. 3-D microscopic image analysis showed a total porosity in unroasted cocoa beans of 8.5 ± 2.0% (v/v): this value doubled upon oven roasting and triplicated upon fluidized bed roasting. The higher porosity in fast-roasted nibs was reflected in the lowest densities and highest cocoa butter yield. Cocoa butter obtained from fluidized-bed roasted cocoa showed a higher presence of pyrazines and 3-methylbutanal, and a lower concentration of hydroperoxides, thus enhancing the chocolate flavor and quality. In this paper, we showed that pore-structure of cocoa nibs is a key quality descriptor of roasting processing, and we concluded by energetic and quality considerations that fluidized bed roasting of cocoa nibs should be preferred over conventional roasting.
The upgrading of oleyl alcohol synthesis via methyl oleate reduction using NaBH4 without H2 supply was investigated. It was possible to synthesize selectively the valuable unsaturated fatty alcohol with high yields. Non-catalytic and catalytic experiments were developed trying to improve the low final oleyl alcohol yield previously obtained. The effect of reaction temperature, methyl oleate/NaBH4 molar ratio and properties of different catalysts on final oleyl alcohol yield was analyzed. Thus, alumina-supported metal (M) catalysts (M = Fe, Ce, Mo) were synthesized by impregnation at incipient wetness. The M/Al2O3 catalysts were characterized in their chemical, textural, structural and acid-base properties using ICP, N2 physisorption, XRD and NH3 and CO2 TPD. During non-catalytic methyl oleate reduction final methyl oleate conversion and oleyl alcohol yield of 94% were obtained using a methyl oleate/NaBH4 molar ratio of 0.11 at 333 K. Catalytic activity of M/Al2O3 solids did not correlate with basic site number but increased as acid site number and ionic potential of M cations increase. This suggests that cations with high acid site number and polarizing power are the ones that promote the polarization of the ester C=O and anion [BH4]- bonds favoring de methyl oleate conversion. In addition, the reaction mechanism for fatty acid methyl ester reduction was investigated from a theoretical approach using Density Functional Theory method at B3LYP/6-31++G(d,p) computational level. Results obtained during theoretical calculations confirmed that the formation of reducing alcoxyborohydride species is energetically favored and allowed to understand the events at microscopic level involved in the reaction mechanism.
The aim of this study was to determine and optimize culture media for Chlorella vulgaris microalgae under mixotrophic conditions using waste molasses as a cheap carbon source containing both organic carbons and other nutrients. In the current study, at first the growth and lipid productivity of Chlorella vulgaris were assessed in different culture media and the best media was selected for mixotrophic growth conditions. Significant medium ingredients were screened through Plackett–Burman design. Then ingredients with positive effect were considered as a mixture component and their combinations were evaluated on lipid productivity using mixture design. According to results, Zarrouk medium was considered as the base medium with the highest biomass and lipid productivity of 72 and 7.1 mg/l.d , respectively. Based on the Plackett–Burman design, out of eleven factors, molasses, NaNO3 and K2HPO4 demonstrated key roles in biomass and lipid productivity in mixotrophic conditions. Consequently, the selected three factors were investigated by mixture design. The results showed that high concentration of molasses causes decrease in biomass and lipid productivity due to high turbidity and a blend consisting of approximately 9.5 g/l molasses, 5 g/l NaNO3 and 0.15 g/l K2HPO4 was found as the optimum mixture with obtained lipid productivity of 115 mg/l.d. In conclusion, waste molasses can be used as a promising feedstock for cost effective cultivation of C. vulgaris.
The initial oleogelation process (microstructuring) as well as the formulation are determinant to obtain the desired characteristics in oleogels with potential application in the industry. The microstructuring process in oleogels has been extensively studied by means of techniques highly sensitive to thermal variations, such as differential scanning calorimetry (DSC). However, there are other readily available techniques and equipment that can be employed to perform similar evaluations. Non-isothermal nucleation kinetics by spectrophotometric methods can be used as alternatives to basic crystallization studies in oleogels. Therefore, in this research a comparison of both techniques is presented, highlighting their similarities, advantages and limitations, in the study of the microstructure of oleogels. Oleogels were obtained with a minimum concentration of gelator and another saturated one, using vegetable oils of different degrees of saturation. The crystallization profiles of the oleogels were obtained by DSC, a non-isothermal nucleation kinetics was performed from the molten system and the final microstructure was evaluated by optical microscopy. The Fisher-Turnbull and Avrami model was used to evaluate the behavior during microstructuring. A gap was observed during the crystallization process by DSC which can be evaluated by spectrophotometry. Differences in the microstructuring process were found in both methods due to the temperature ramp used and formulation variables. The results obtained by spectrophotometry indicate that it can be a good alternative, easily accessible in oleogel crystallization studies, when high sensitivity or very specific thermal parameters are not required.
Protein extraction from soybeans is a vital part of the soy industry. Traditionally, the extraction of soy protein has been done by alkaline extraction and isoelectric precipitation. As technology has advanced, more extraction techniques are superior to this traditional method. In this review, the composition and classification of soy protein are summarized. Next, the current emerging technologies for soy protein extraction are highlighted. Three extraction technologies, namely reverse micellar, enzyme-assisted and membrane ultrafiltration, are reviewed in detail. Finally, the research prospects and trends of soy protein extraction technology are also summarized.
Glycerol monooleate (GMO)-stabilized liquid water-in-vegetable oil (W/VO) emulsions are difficult to stabilize due to the desorption of GMO from the W-VO interface towards the oil phase. This work improved the stability of GMO-stabilized liquid 20 wt% water-in-canola oil (W/CO) emulsion by modifying the dispersed aqueous phase composition with hydrogen bond-forming agents. As a control, 20 wt% water-in-mineral oil (W/MO) emulsion was also utilized. Different concentrations of hydrogen bond-forming agents (citric acid (CA), ascorbic acid (AA), low methoxyl pectin (LMP)) with and without salts (sodium chloride (S) or calcium chloride (Ca)) was added to the aqueous phase before emulsification, which enhanced emulsifier binding to the water-oil interface. The emulsions were characterized by phase separation, stability against accelerated gravitation, microstructure and rheology. W/CO emulsion without any aqueous phase additive destabilized instantly, whereas W/MO emulsion stayed stable. The addition of hydrogen bond-forming agents and salts significantly improved emulsion stability. LMP, with many hydrogen bond-forming groups, was able to provide the highest emulsion stability after 7 days in both oils compared to AA, CA and their mixtures with S. Emulsions with both oils formed weak gels with viscous and elastic characteristics due to the formation of an extensive network of water droplet aggregates. Overall, the hydrogen bond-forming agents interacted with GMO at the interface, thereby improving their presence at the water droplet surface, allowing significantly improved stability of GMO-stabilized liquid W/CO emulsions. The knowledge developed in this research can be useful in applying GMO in stabilizing liquid water-in-oil emulsion without using any crystal network.
Striped mullet (Mugil cephalus) roe is used for the production of traditional delicacies in Greece (avgotaracho), Japan (karasumi) and Italy (botargo). In Greece avgotaracho is a Protected Designation of Origin product and its special taste combined with its high nutritional value of this rich in polyunsaturated fatty acids (PUFA) and bioactive compounds delicacy attracts many consumers. During the production of avgotaracho and the similar products some of the egg sacs (skeins) either break or have an inappropriate size (too small) and they can not be used for avgotaracho production. On the other hand the nutritional quality of the eggs in the broken or smaller skein is by no means inferior comparing to the rest. Proper valorization of the mullet roe by-products could lead to high nutrition value products. This work focuses on examining the potential valorization of these high nutritional value by-products for producing mullet roe oil. Three different extraction methods with potential of scale-up are examined. Namely pressure, supercritical extraction, solvent extraction are examined where mild temperature conditions and (wherever applicable) food-grade solvents are used. The oil yield, the composition of oils in fatty acids by GC-FID, the level of oil oxidation (peroxide value, p-anisidine value, K232 K268, TOTOX) and antioxidant activity (DPPH, ABTS) are determined. The potential of the above extraction methods for the production of mullet roe oil in terms of yield and oil quality is discussed.