Influence of physicochemical interactions between amylose and aroma compounds on the retention of aroma in food-like matrices

Mutual Relations between Texture and Aroma of Cooked Rice-A Pilot Study

Texture and aroma are two important attributes for the eating quality of cooked rice, but their mutual relations are not clear. Cooked rice with a desirable texture might suffer from a deteriorated aroma property. To better understand the relations between texture and aroma, six different rice varieties with desirable eating qualities have been selected, with their texture and aroma profile characterized by a texture analyzer and gas chromatography-ion mobility spectrometry, respectively. A large variance of textural attributes and a total number of 39 major volatile organic components were observed for these cooked rice varieties. Pearson correlation showed that the hardness of cooked rice was positively correlated with the content of E-2-hexenal, 2-hexanol-monomer, 1-propanol, and E-2-pentenal, while stickiness was positively correlated with 5-methyl-2-furanmethanol and dimethyl trisulfide. Possible underneath mechanisms were discussed for these relations. These results could help the rice industry to develop rice products with both desirable texture and aroma property.

Effects of composition and storage time of biopolymers-based emulsion-filled gels on the retention and release of aroma compounds: Thermodynamic and kinetic studies

Studies were performed to determine retention (R) and release kinetics (k_r) of aroma compounds (ACs): ethyl butyrate, linalool, 1-octen-3-ol, 2-heptanone and octanal from emulsion-filled gels (EFGs), stabilized by myofibrillar proteins and waxy rice starch (WRS) or tapioca starch (TS). The R and k_r parameters were affected by non-covalent interactions of ACs with biopolymers and the development of a compact structure induced by starch addition. Higher k_r magnitudes were found in WRS-based samples (88.2-12.8 × 10^-3 day^-1) than in counterparts prepared with TS (87.6-8.96 × 10^-3 day^-1). Thermodynamic tests revealed that vaporization enthalpies of ACs were in ranges: 22.6-41.2 kJ mol^-1 or 21.4-39.8 kJ mol^-1 in samples containing WRS or TS, respectively. This study provides new insight into the factors affecting ACs stability in the EFGs, and the results reported can be used by industry to design relevant systems with extended volatiles retention.

Encapsulation of Fruit Flavor Compounds through Interaction with Polysaccharides

Production and storage, the influence of packaging materials and the presence of other ingredients in fruit products can cause changes in flavor compounds or even their loss. Due to these issues, there is a need to encapsulate flavor compounds, and polysaccharides are often used as efficient carriers. In order to achieve effective encapsulation, satisfactory retention and/or controlled release of flavor compounds, it is necessary to understand the nature of the coated and coating materials. Interactions that occur between these compounds are mostly non-covalent interactions (hydrogen bonds, hydrophobic interactions and van der Waals forces); additionally, the formation of the inclusion complexes of flavor compounds and polysaccharides can also occur. This review provides insight into studies about the encapsulation of flavor compounds, as well as basic characteristics of encapsulation such as the choice of coating material, the effect of various factors on the encapsulation efficiency and an explanation of the nature of binding.

Contribution of starch to the flavor of rice-based instant foods

Increased consumption of instant foods has led to research attention, especially rice-based instant foods. Starch, one of the most important components of rice, significantly affects food quality. However, the mechanisms by which starch contributes to rice-based instant foods flavor are poorly understood in many cases. The review aims to describe the common mechanisms by which starch contributes to food flavor, including participating in flavor formation, and affecting flavor release throughout starch multiscale structure: particle morphology, crystal structure, molecular structure. Five specific examples of rice-based instant foods were further analyzed to summarize the specific contribution of starch to flavor, including instant rice, fermented rice cake, rice noodles, fried rice, and rice dumplings. During foods processing, reducing sugars produced by heating or enzymatic hydrolysis of starch participate in Maillard reaction, caramelization and thermal degradation, which directly or indirectly affect the formation of flavor compounds. In addition, adsorption by granules, encapsulation by retrograded V-type crystal, and controlled release by starch gel all contribute to rice-based instant food flavor qualities. These mechanisms jointly contribute to flavor compounds formation and release. Proper theoretical application and improved processing methods are needed to promote the high-quality, mechanization, and automation of rice-based instant foods production.

Real-Time Monitoring of Volatile Compounds Losses in the Oven during Baking and Toasting of Gluten-Free Bread Doughs: A PTR-MS Evidence

Losses of volatile compounds during baking are expected due to their evaporation at the high temperatures of the oven, which can lead to a decrease in the aroma intensity of the final product, which is crucial for gluten-free breads that are known for their weak aroma. Volatiles from fermentation and lipids oxidation are transferred from crumb to crust, and they flow out to the air together with Maillard and caramelisation compounds from the crust. In this study, the release to the oven of volatile compounds from five gluten-free breads (quinoa, teff and rice flours, and corn and wheat starches) and wheat bread during baking and toasting was measured in real-time using proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS). Baking showed different volatile release patterns that are described by bell-shaped curves, plateaus and exponential growths. Flour-based breads had the higher overall volatile release during baking, but also high ratios in the final bread, while starch-based breads showed high pyrazine releases due to moisture losses. Meanwhile, toasting promoted the release of volatile compounds from the bread matrix, but also the additional generation of volatiles from Maillard reaction and caramelisation. Interestingly, gluten-free breads presented higher losses of volatiles during baking than wheat bread, which could partially explain their weaker aroma.

Characterization of the Key Aroma Constituents in Fry Breads by Means of the Sensomics Concept

The key aroma constituents in the volatile fractions isolated FROM two differently processed fry breads by solvent-assisted flavor evaporation were characterized by an aroma extract dilution analysis (AEDA). Twenty-two compounds were identified with flavor dilution (FD) factor ranges of 2–516. Among them, 13 compounds (FD ≥ 16) were quantified by stable isotope dilution assays and analyzed by odor activity values (OAVs). Of these, 11 compounds had OAVs ≥ 1, and the highest concentrations were determined for δ-decalactone and 2,3-butanedione. Two recombination models of the fry breads showed similarity to the corresponding fry breads. Omission tests confirmed that aroma-active constituents, such as δ-decalactone (oily/peach), 2-acetyl-1-pyrroline (roasty/popcorn-like), 3-methylbutanal (malty), methional (baked potato-like), 2,3-butanedione (buttery), phenyl acetaldehyde (flowery), (E,E)-2,4-decadienal (deep-fried), butanoic acid, and 3-methylbutanoic acid, were the key aroma constituents of fry bread. In addition, 3-methoxy-4-vinylphenol (smoky) and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were also identified as important aroma constituents of fry bread.

Cellulose as a Delivery System of Raspberry Juice Volatiles and Their Stability

Formulation of delivery systems for active ingredients is of increasing importance for the food industry. For that purpose, we selected cellulose as a carrier polymer of raspberry volatiles. Freeze-dried cellulose/raspberry complexes were prepared by complexation of raspberry juice (constant amount) and cellulose (2.5%, 5%, 7.5% and 10%). In our study, cellulose was shown as a good carrier of raspberry juice volatiles. Thirty-nine volatiles were detected in raspberry juice while 11 of them were lost during preparation of the complexes. Berry flavor note was the dominant one in raspberry juice (40% of overall flavor), followed by citrus and woody notes (each around 18% of overall flavor) and floral, fruity, and green (each around 8% of overall flavor). Cellulose/raspberry complexes had different flavor profiles, but a berry flavor note was still the dominant one in all complexes. These results suggest an efficient plant-based approach to produce value-added cellulose/volatile dry complexes with possible utility as food flavoring ingredients.

Analytical feasibility of a solvent-assisted flavour evaporation method for aroma analyses in bread crumb

The analysis of bread aroma is essential in order to evaluate its quality as well as to improve it. The use of different methodologies for the analysis of volatile compounds lead to varying results. In the present study, the matrix effect, extraction efficiency, limits of detection and quantification as well as the precision of a proposed solvent-assisted flavour evaporation methodology were evaluated for the first time and compared with a reference method, both differing in the distillation step. The repeatability (<8%) and matrix effect (present in 15 of the 31 compounds) were improved with the proposed method but the extraction efficiencies (average of 52%) and the intermediate precision (>15%) were not as required. However, the applicability of the reference method was limited to breads with fat levels <2%. For breads higher in fat, the proposed method represents an alternative for aroma analysis.

Comparative Structural Characterization of Spiral Dextrin Inclusion Complexes with Vitamin E or Soy Isoflavone

In this study, the preparation and structural properties of spiral dextrin (SD)/vitamin E and SD/soy isoflavone inclusion complexes were studied. SD was obtained from debranched normal maize starch using isoamylases. After fractionation using a novel method of gradient ethanol precipitation, SD was separated into different fractions, among which SD-40 was found to be the optimal host molecule to prepare SD inclusion complexes with vitamin E or soy isoflavone. X-ray diffraction (XRD) and 13C cross-polarization magic angle spinning nuclear magnetic resonance (NMR) suggested that the crystalline structures of SD-40/vitamin E and SD-40/soy isoflavone were V6II and V6III types, respectively. Small-angle X-ray scattering revealed that the SD-40/vitamin E inclusion complex formed a tighter and more compact crystallite than the SD-40/soy isoflavone inclusion complex. Furthermore, the connection structures of inclusion complexes were investigated by two-dimensional nuclear Overhauser effect spectroscopy NMR, indicating that part of vitamin E with an alkyl chain was encapsulated in the helix cavity of SD-40, whereas the aromatic ring B of the soy isoflavone molecule was complexed by the helix cavity and screw of SD.

Impact of frozen storage time on the volatile profile of wheat bread crumb

The freezing of wheat bread before aroma analyses is a common practice in order to preserve loss of the volatile profile. However, the impact of the frozen storage time on the aroma profile has not been studied. For this purpose, the volatile profiles of wheat bread frozen for 1, 2 and 4weeks were analysed employing solvent extraction and static headspace methoologies with GC/MS. The results revealed that the freezing was effective to prevent the loss of volatiles during the first week. However, after two weeks, there was an increase of volatile compounds, probably generated by chemical reactions. Thus, a maximum of one week of frozen storage was recommended when using the solvent extraction methodology. When using the static headspace method, the samples should be analysed on the same day as preparation, since the extraction was surprisingly increased due to the starch retrogradation that occurred during freezing.

Effects of Agar Gel Strength and Fat on Oral Breakdown, Volatile Release, and Sensory Perception Using in Vivo and in Vitro Systems

The density and composition of a food matrix affect the rates of oral breakdown and in-mouth flavor release as well as the overall sensory experience. Agar gels of increasing concentration (1.0, 1.7, 2.9, and 5% agarose) with and without added fat (0, 2, 5, and 10%) were spiked with seven aroma volatiles. Differences in oral processing and sensory perception were systematically measured by a trained panel using a discrete interval time intensity method. Volatile release was measured in vivo and in vitro by proton transfer reaction mass spectrometry. Greater oral processing was required as agar gel strength increased, and the intensity of flavor-related sensory attributes decreased. Volatile release was inversely related to gel strength, showing that physicochemical phenomena were the main mechanisms underlying the perceived sensory changes. Fat addition reduced the amount of oral processing and had differential effects on release, depending on the fat solubility or lipophilicity of the volatiles.

Preparation and characterization of corn starch-β-carotene composites

Starch-β-carotene composites were generated by drop-wise addition of ethanol comprising varying β-carotene contents (5, 10, or 20mg) into starch pastes (1, 3, or 5% w/v) to improve water-dispersibility and stability of β-carotene. The mean diameter of the composites was less than 900 nm, allowing particles to be homogeneously dispersed in aqueous media for over two weeks without sedimentation. X-ray diffraction and differential scanning calorimetry analysis confirmed the composite mainly consisted of Vh-amylose, amorphous starch matrices, and starch-β-carotene ordered structures. Both amorphous matrices and Vh-amylose structures in the composite were readily digested within 20 min in vitro digestion, while highly ordered structures, which melted between 132 and 159 °C, exhibited inhibited and/or delayed enzymatic digestion. As more β-carotene was incorporated into the composite, the β-carotene content of the ordered structure was increased. Formation of starch-β-carotene composites also appeared to enhance the stability of β-carotene against chemical oxidation.

Preparation and characterization of debranched-starch/phosphatidylcholine inclusion complexes

In this study, debranched-starch/phosphatidylcholine inclusion complexes were prepared. The effect of reaction parameters such as reaction temperature, reaction time, and addition amount of phosphatidylcholine on the phosphatidylcholine payload and inclusion rate was investigated. The phosphatidylcholine payload and inclusion rate prepared under the optimal conditions were 106 mg/g and 84.8%, respectively. The formation of debranched-starch/phosphatidylcholine inclusion complexes was confirmed by the results of XRD and FT-IR. Furthermore, the molecular, cluster, and fractal structures of the complexes were investigated using (13)C CP/MAS NMR and SAXS. The results indicated that the inclusion complexes were formed by hydrophobic interactions between alkyl chain of phosphatidylcholine and debranched-starch helix cavity. The complexes possessed a mass fractal structure, and a semicrystalline structure with a Bragg distance of 19.04 nm formed. After complexation, the stability of phosphatidylcholine was significantly improved, and phosphatidylcholine of the complexes can be gradually released with pancreatin treatment. This study revealed that debranched-starch can be used as an effective carrier of phosphatidylcholine for the purpose of improving its stability.

Evaluation of Different Analysis Methods for the Encapsulation Efficiency of Amylose Inclusion Compound

Recently amylose has drawn much attention as a potential vehicle for the nanoencapsulation of different flavor molecules, and the encapsulation efficiency of the complex is an important index for the evaluation of its embedding effect. In this study, three different methods for assessing encapsulation efficiency of amylose-flavor complexes were compared. We chose heptanol and menthone as the flavor molecules, as both of them exhibit a typical odor. The complexes were prepared by the melting method, and their structures were characterized by XRD. In addition, the encapsulation efficiency was determined by thermal gravimetric analysis (TGA), potentiometric titration (PT), and headspace solid phase microextraction gas chromatography (HS-SPME-GC), respectively. The results showed that PT results were within the reported literature range while HS-SPME-GC seemed to overestimate the results and TGA results were the lowest. What is more, the operations of TGA and PT were relatively simple and the results were reproducible, while the HS-SPME-GC method displayed excellent high sensitivity. Therefore, PT method is the best method for assessing encapsulation efficiency of amylose-flavor complexes.

Partition of volatile compounds in pea globulin-maltodextrin aqueous two-phase system

This study is based on the assumption that the off-flavour of pea proteins might be decreased using the retention of volatile compounds by a mixture with another biopolymer. The partition of volatile compounds in an aqueous system containing pea protein and maltodextrins was followed under thermodynamic incompatibility conditions. Firstly, the phase diagram of the system was established. Then, the partition of aroma compounds between the phase rich in protein and the phase rich in maltodextrin was measured by SPME-GC-MS. There was a transfer of volatile compounds during phase separation. Variations of pH were also used to vary the retention of volatile compounds by proteins. The concentration of volatile compounds in protein solution at pH 2.4 was higher than at pH 7.2. It was possible to increase the transfer of volatile compounds from the phase rich in protein to the phase rich in maltodextrin using the effect of pH on protein denaturation.

Effect of konjac glucomannan addition on aroma release in gels containing potato starch

The present study aimed to measure the retention of aroma compounds (ethyl acetate, ethyl hexanoate and carvacrol) in dispersions based on konjac glucomannan and/or potato starch, and to highlight the influence of konjac glucomannan on the mechanisms involved in aroma retention. Publications on the effect of konjac glucomannan on aroma release are scarce. Konjac glucomannan is a polysaccharide used as a food additive for its viscous and emulsifying properties. Retention of aroma compounds in dispersions was calculated from partition coefficients which were measured using the phase ratio variation method. This method, consisting of analyses of the headspace at equilibrium, enables the determination of the partition coefficient of volatile compounds in a gas/liquid system without external or internal calibration. The three aroma compounds chosen for this study behave differently toward amylose. Prior to the release study, the complexing behavior of carvacrol with starch, hitherto unknown, was investigated by X-ray diffraction: V_6III amylose complexes were formed with carvacrol. Our results showed no specific interaction between ethyl hexanoate and potato starch or konjac glucomannan. Ethyl acetate retention seemed to be due to trapping in the complex network of polysaccharides and to the density of this network. Retention of carvacrol was influenced by the nature of polysaccharides present in the dispersion, and was mainly governed by specific interaction with starch. Additionally, the addition of konjac glucomannan to potato starch dispersions decreased the retention of volatile compounds complexing starch, but had little effect on the retention of the other aroma compounds.

Interaction between hydroxyethyl starch and propofol: computational and laboratorial study

BACKGROUND

Hydroxyethyl starch (HES) is one of the most used colloids for intravascular volume replacement during anesthesia.

AIM

To investigate the existence of a chemical interaction between HES and the anesthetic propofol by in vitro propofol dosing, computational docking, and examination of a complex between propofol and HES by infrared (IR), ultraviolet (UV), and (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy.

METHODS

Ten samples with human plasma mixed with HES or lactated Ringers (n = 5 for each fluid) were prepared, and the propofol free fraction was quantified until 50 min, using gas chromatography-mass spectrometry. The docking study was performed between HES and propofol and compared with controls. The binding affinities between HES and the small molecules were evaluated by binding free energy approximation (ΔGb, kJ mol(-1)). The IR, UV, and NMR spectra were measured for propofol, HES, and a mixture of both obtained by the kneading method.

RESULTS

Propofol concentrations were significantly lower in the HES samples than in the LR samples (p = .021). The spectroscopic characterization of propofol combined with HES revealed differences in spectra and docking studies reinforced a potential interaction between propofol and HES.

CONCLUSIONS

Propofol and HES form a complex with different physical-bio-chemical behavior than the single drugs, which may be an important drug interaction. Further studies should evaluate its clinical effects.

Improving bioavailability and stability of genistein by complexation with high-amylose corn starch

Genistein, like other phytochemicals, has beneficial health effects, but its bioavailability is limited. This research studied the effect of complexation of genistein with starch on genistein bioavailability. Genistein release from these complexes was tested in vitro under simulated intestinal conditions and in vivo in rats fed high-amylose corn starch (HACS)-genistein complexes (experimental group) as compared to those fed a physical mixture of HACS and genistein (controls). In vitro results showed that genistein release is sustained and fits the normal transit time of food in the intestine. The genistein concentration in the plasma was twice as high in the experimental group versus controls; the genistein concentration in the urine was also higher in the experimental group but lower in the feces. These results indicate that starch-genistein complexes increase genistein bioavailability and suggest that starch can affect the bioavailability of additional food components.

Influence of complexation between amylose and a flavored model sponge cake on the degree of aroma compound release

Flavoring is used in the food industry to reinforce the aroma profile of baked cereal goods. During the processing of such products, interactions between starch and aroma compounds can occur, and this may have an impact on aroma release and perception. In the present study, 20 aroma compounds were tested to establish whether they formed complexes with amylose. The structure of the complexes was determined by wide-angle X-ray scattering (WAXS). A cocomplexation study proved that several complexing compounds could be present in the same crystalline aggregate. WAXS and differential scanning calorimetry (DSC) experiments were performed in a flavored model sponge cake at different steps of processing and showed that aroma compounds might form complexes with amylose in a sponge cake as they can do in simple system containing only amylose. Some of the aroma compounds trapped in the sponge cake were quantified, and their release behavior was followed by headspace analysis. The V-type structure could partly explain aroma retention in the product and the rate of aroma release.