Effects of pH on protein components of extracted oil bodies from diverse plant seeds and endogenous protease-induced oleosin hydrolysis

Effect of extraction pH on the emulsion stability and surface protein structure of soybean oil body

In this study, the pH was varied (6.0-11.0) during the extraction of soybean oil body (SOB), and the stabilities of the corresponding emulsions as well as the structural properties of SOB surface proteins were investigated. The extraction pH was found to affect both the SOB emulsion stability and surface protein structure. Micromorphological analysis showed that the degree of SOB dispersion was higher under alkaline conditions compared to other treatment conditions (acidic or neutral). Structural changes in the SOB surface proteins, as evaluated using changes in the α-helix and β-sheet contents and fluorescence intensity, were more pronounced when extraction was performed at pH 11.0. Structural changes in SOB surface proteins also affected the amino acid fractions, surface hydrophobicity, and free sulfhydryl content. Overall, an extraction pH of 11.0 resulted in optimal SOB emulsion stability and had the greatest effect on the structural properties of the SOB surface proteins.

Proteolysis and lipolysis induced by acidification of sesame seeds

Vinegar-soaked seeds can be consumed as functional foods, and the acidification of vacuoles during seed germination is key for protein mobilization. Inspired by these, sesame seeds, containing proteases with peak activity at pH 4.5, were soaked in a 2 % acetic acid solution at 25 °C. Transmission electron microscopy showed that the acidic sesame proteases localized in protein storage vacuoles (PSVs), while liquid chromatography tandem mass spectrometry identified nine lipases. The seeds were acidified to pH 4.5 within 9 h, and the proteases were fully activated to hydrolyze the storage proteins and tonoplast of PSVs. The proteases were released and attacked almost all organelles. Oil body membrane proteins were degraded, causing the inner oil accessible to lipases. By 7 days of soaking, the protein components in the soaking system consisted of 39 % small peptides and 31 % free amino acids, while the oil was hydrolyzed into 26 % free fatty acids and 13 % diacylglycerols.

Performance of an integrated system for the treatment of veterinary hospital wastewaters: assessment of organic load and toxicity levels

Despite its toxic potential, the treatment of wastewaters generated at veterinary hospitals has been neglected. Thus, this is a pioneering study that addresses the treatment of this effluent through an integrated system composed of an upflow anaerobic sludge blanket (UASB), an anoxic filter (AF), an aerobic reactor (AR), a sludge thickener tank (STT) a horizontal flow subsurface constructed wetland (HFSSCW) and a parshall gutter (PG) and with a hydraulic retention time of 10 days. Approximately 5 m³ of wastewater is produced daily, with antibiotics and analgesics being the most commonly used classes of pharmaceutical compounds. Several of the analyzed parameters did not comply with national and international guidelines. In this context, the integrated treatment system demonstrated good results, achieving mean removals of: 98% for COD and 59% for BOD5; 87.5% for Total N and 44% for Total P; 83.8% and 69.9% for DOC and TDC; 95% and 65% for Turbidity and EC; and 78% for TDS. The bioassays with Allium cepa indicated a strong genotoxic potential of the raw wastewater, which was completely eliminated after treatment. Thus, it can be concluded that the integrated treatment system showed promising results regarding the treatment of the investigated wastewaters and can be considered a viable alternative to meet effluent disposal limits established in Brazilian and international standards, as well as significantly reduce their toxic potential.

Assembly of oleosin during efficient extraction: Altering the sequence of defatting solvents

During the extraction of membrane proteins from oil bodies (OBs), organic solvents dissolve the lipid core and precipitate proteins through solvent stress. Here the effects of solvent type and defatting sequence on the composition and structure of membrane proteins were investigated via SDS-PAGE, FTIR, and SEM-EDS. High purity oleosin (86 %) was obtained by treatment first with a Floch solution and then with cold acetone and petroleum ether after twice washing OBs with urea. The 3D spatial structure of oleosin was predicted using AlphaFold 2, revealing that the secondary structure of oleosin was dominated by α-helices (>60 %). Oleosin consisted of two district types, with oleosin-H (16-17 kDa) being the part of the molecule with limited water solubility, while oleosin-L (13-14 kDa) constituted the non-soluble part. The results provided a technical means of efficient extraction of Camellia oleosins and selective separation of oleosin-L and oleosin-H.

Unveiling the applications of membrane proteins from oil bodies: leading the way in artificial oil body technology and other biotechnological advancements

Oil bodies (OBs) function as organelles that store lipids in plant seeds. An oil body (OB) is encased by a membrane composed of proteins (e.g., oleosins, caleosins, and steroleosins) and a phospholipid monolayer. The distinctive protein-phospholipid membrane architecture of OBs imparts exceptional stability even in extreme environments, thereby sparking increasing interest in their structure and properties. However, a comprehensive understanding of the structure-activity relationships determining the stability and properties of oil bodies requires a more profound exploration of the associated membrane proteins, an aspect that remains relatively unexplored. In this review, we aim to summarize and discuss the structural attributes, biological functions, and properties of OB membrane proteins. From a commercial perspective, an in-depth understanding of the structural and functional properties of OBs is important for the expansion of their applications by producing artificial oil bodies (AOB). Besides exploring their structural intricacies, we describe various methods that are used for purifying and isolating OB membrane proteins. These insights may provide a foundational framework for the practical utilization of OB membrane proteins in diverse applications within the realm of AOB technology, including biological and probiotic delivery, protein purification, enzyme immobilization, astringency detection, and antibody production.

Effects of Roasting Temperatures on Peanut Oil and Protein Yield Extracted via Aqueous Enzymatic Extraction and Stability of the Oil Body Emulsion

Oil body emulsions (OBEs) affect the final oil yield as an intermediate in the concurrent peanut oil and protein extraction process using an aqueous enzyme extraction (AEE) method. Roasting temperature promotes peanut cell structure breakdown, affecting OBE composition and stability and improving peanut oil and protein extraction rates. Therefore, this study aimed to investigate the effects of pretreatment at different roasting temperatures on peanut oil and protein yield extracted through AEE. The results showed that peanut oil and protein extraction rates peaked at 90 °C, 92.21%, and 77.02%, respectively. The roasting temperature did not change OBE composition but affected its stability. The OBE average particle size increased significantly with increasing temperature, while at 90 °C, the zeta potential peaked, and the interfacial protein concentration hit its lowest, indicating OBE stability was the lowest. Optical microscopy and confocal laser scanning microscopy confirmed the average particle size findings. The oil quality obtained after roasting treatment at 90 °C did not differ significantly from that at 50 °C. The protein composition remained unaffected by the roasting temperature. Conclusively, the 90 °C roasting treatment effectively improved the yield of peanut oil extracted using AEE, providing a theoretical basis for choosing a suitable pretreatment roasting temperature.

Molecular Machinery of Lipid Droplet Degradation and Turnover in Plants

Lipid droplets (LDs) are important organelles conserved across eukaryotes with a fascinating biogenesis and consumption cycle. Recent intensive research has focused on uncovering the cellular biology of LDs, with emphasis on their degradation. Briefly, two major pathways for LD degradation have been recognized: (1) lipolysis, in which lipid degradation is catalyzed by lipases on the LD surface, and (2) lipophagy, in which LDs are degraded by autophagy. Both of these pathways require the collective actions of several lipolytic and proteolytic enzymes, some of which have been purified and analyzed for their in vitro activities. Furthermore, several genes encoding these proteins have been cloned and characterized. In seed plants, seed germination is initiated by the hydrolysis of stored lipids in LDs to provide energy and carbon equivalents for the germinating seedling. However, little is known about the mechanism regulating the LD mobilization. In this review, we focus on recent progress toward understanding how lipids are degraded and the specific pathways that coordinate LD mobilization in plants, aiming to provide an accurate and detailed outline of the process. This will set the stage for future studies of LD dynamics and help to utilize LDs to their full potential.

Effects of Quillaja Saponin on Physicochemical Properties of Oil Bodies Recovered from Peony (Paeonia ostii) Seed Aqueous Extract at Different pH

Peony seeds, an important oil resource, have been attracting much attention because of α-linolenic acid. Oil bodies (OBs), naturally pre-emulsified oils, have great potential applications in the food industry. This study investigated the effects of extraction pH and Quillaja saponin (QS) on the physicochemical properties of peony oil body (POB) emulsions. POBs were extracted from raw peony milk at pH 4.0, 5.0, 6.0, and 7.0 (named pH 4.0-, 5.0-, 6.0-, and 7.0-POBs). All POBs contained extrinsic proteins and oleosins. The extrinsic proteins of pH 4.0- and pH 5.0-POB were 23 kDa and 38 kDa glycoproteins, the unknown proteins were 48 kDa and 60 kDa, while the 48 kDa and 38 kDa proteins were completely removed under the extraction condition of pH 6.0 and 7.0. The percentage of extrinsic proteins gradually decreased from 78.4% at pH 4.0-POB to 33.88% at pH 7.0-POB, while oleosin contents increased. The particle size and zeta potential of the POB emulsions decreased, whereas the oxidative stability, storage stability, and pI increased with the increasing extraction pH. QS (0.05~0.3%) increased the negative charges of all the POB emulsions, and 0.1% QS significantly improved the dispersion, storage, and the oxidative stability of the POB emulsions. This study provides guidance for selecting the proper conditions for the aqueous extraction of POBs and improving the stability of OB emulsions.

A novel integrated automatic strategy for amino acid composition analysis of seeds from 67 species

The composition and quantity of amino acids (AAs) in seeds are complicated due to the various origins and modifications of different species. In this study, a novel automatic neutral loss filtering (ANLF) strategy based on accurate mass searching by Python was developed to analyze the free and hydrolyzed AA-phenyl isothiocyanate (PITC) derivatives from seeds of Gymnosperm and Angiosperm phyla. Compared with traditional strategies, ANLF showed much higher accuracy in screening AA derivatives by filtering nitrogen-containing non-AA compounds and efficiency in processing large datasets. Meanwhile, the content phenotype of 20 proteinogenic AAs from seeds of these two families was characterized by a 35-min HPLC method combined with an automated peak-matching strategy. AA profiles of 232 batches of seeds from 67 species, consisting of 19 proteinogenic AAs, 21 modified AAs, and 77 unknown AAs, would be a good reference for their application in food and medicine.

Lipid Droplets from Plants and Microalgae: Characteristics, Extractions, and Applications

Plant and algal LDs are gaining popularity as a promising non-chemical technology for the production of lipids and oils. In general, these organelles are composed of a neutral lipid core surrounded by a phospholipid monolayer and various surface-associated proteins. Many studies have shown that LDs are involved in numerous biological processes such as lipid trafficking and signaling, membrane remodeling, and intercellular organelle communications. To fully exploit the potential of LDs for scientific research and commercial applications, it is important to develop suitable extraction processes that preserve their properties and functions. However, research on LD extraction strategies is limited. This review first describes recent progress in understanding the characteristics of LDs, and then systematically introduces LD extraction strategies. Finally, the potential functions and applications of LDs in various fields are discussed. Overall, this review provides valuable insights into the properties and functions of LDs, as well as potential approaches for their extraction and utilization. It is hoped that these findings will inspire further research and innovation in the field of LD-based technology.

Extraction of structurally intact and well-stabilized rice bran oil bodies as natural pre-emulsified O/W emulsions and investigation of their rheological properties and components interaction

The isolated plant oil bodies (OBs) have shown promising applications as natural pre-emulsified O/W emulsions. Rice bran OBs can be used as a new type plant-based resource with superior fatty acids composition and abundant γ-oryzanol. This paper investigated the method of extracting structurally intact and stable rice bran OBs. Due to the adequate steric hindrance and electrostatic repulsion effects, rice bran OBs extracted by NaHCO₃ medium had smaller particle size, better physical stability, and natural structure. The protein profile of NaHCO₃-extracted rice bran OBs showed oleosin-L and oleosin-H, while exogenous proteins in PBS and enzyme-assisted- extracted rice bran OBs could interact with interfacial proteins through hydrophobic forces to aggregate adjacent OBs, further remodeling the OBs interface. It was also found that the small-sized rice bran OBs could adsorb on the interface of the larger-sized rice bran OBs like Pickering stabilizers. Rice bran OBs exhibited pseudoplastic fluids characteristic, but underwent a transition from solid-like to liquid-like behavior depending on the extraction method. The disorder of NaHCO₃-extracted rice bran OBs protein molecules increased their surface hydrophobicity. The random coil structure favored more proteins adsorption at the interface of rice bran OBs extracted by PBS. Enzyme-assisted extraction of rice bran OBs had the highest content of β-sheet structure, which facilitated the stretching and aggregation of protein spatial structure. It was also confirmed the hydrogen bonding and hydrophobic interaction between the triacylglycerol or phospholipid and proteins molecules, and the membrane compositions of rice bran OBs differed between extraction methods.

Effect of maltodextrin on the oxidative stability of ultrasonically induced soybean oil bodies microcapsules

Introduction

Encapsulation of soybean oil bodies (OBs) using maltodextrin (MD) can improve their stability in different environmental stresses and enhance the transport and storage performance of OBs.

Methods

In this study, the effects of different MD addition ratios [OBs: MD = 1:0, 1:0.5, 1:1, 1:1.5, and 1:2 (v/v)] on the physicochemical properties and oxidative stability of freeze-dried soybean OBs microcapsules were investigated. The effect of ultrasonic power (150–250 W) on the encapsulation effect and structural properties of oil body-maltodextrin (OB-MD) microcapsules were studied.

Results

The addition of MD to OBs decreased the surface oil content and improved the encapsulation efficiency and oxidative stability of OBs. Scanning electron microscopy images revealed that the sonication promoted the adsorption of MD on the surface of OBs, forming a rugged spherical structure. The oil-body-maltodextrin (OB-MD) microcapsules showed a narrower particle size distribution and a lower-potential absolute value at an MD addition ratio of 1:1.5 and ultrasonic power of 250 W (32.1 mV). At this time, MD-encapsulated OBs particles had the highest encapsulation efficiency of 85.3%. Ultrasonic treatment improved encapsulation efficiency of OBs and increased wettability and emulsifying properties of MD. The encapsulation of OBs by MD was improved, and its oxidative stability was enhanced by ultrasound treatment, showing a lower hydrogen peroxide value (3.35 meq peroxide/kg) and thiobarbituric acid value (1.65 μmol/kg).

Discussion

This study showed that the encapsulation of soybean OBs by MD improved the stability of OBs microcapsules and decreased the degree of lipid oxidation during storage. Ultrasonic pretreatment further improved the encapsulation efficiency of MD on soybean OBs, and significantly enhanced its physicochemical properties and oxidative stability.

Raw walnut kernel: A natural source for dietary proteases and bioactive proteins

Walnut kernels are health-promoting nuts, which are mainly attributed to polyunsaturated fatty acids, phenolics, and phytosterols. However, the information concerning benefits of walnut proteins are limited. In this study, endopeptidases, aminopeptidases, carboxypeptidases, superoxide dismutases, catalases, and phospholipases with respective relative abundance of 2.730, 1.728, 0.477, 3.148, 0.743, and 0.173‰ were identified by liquid chromatography tandem mass spectrometry. These endogenous proteases exhibited activity in a broad pH range of 2-6.5, and optimal at pH 4.5 and 50 °C. Aspartic endopeptidases were predominant endopeptidases, followed by cysteine ones. There were two types of aspartic endopeptidases, one (not inhibited by pepstatin A) exerted activity at pH 2-3 and the other (inhibited by pepstatin A) optimal at pH 4.5. Carboxypeptidases were optimal at pH 4.5, and aminopeptidases exerted activity at pH near 6.5. These endogenous proteases assisted the digestion of walnut proteins, and soaking, especially peeling, greatly improved the in vitro digestibility.

Structural and Physicochemical Characteristics of Oil Bodies from Hemp Seeds (Cannabis sativa L.)

The structural and physicochemical characteristics of oil bodies from hemp seeds were explored in this study. Oil bodies from several plant-based sources have been previously studied; however, this is the first time a characterisation of oil bodies from the seeds of industrial hemp is provided. The morphology of oil bodies in hemp seeds and after extraction was investigated using cryo-scanning electron microscopy (cryo-SEM), and the interfacial characteristics of isolated oil bodies were studied by confocal laser scanning microscopy (CLSM). Proteins associated with oil bodies were characterised using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The effect of pH and ionic strength on colloidal properties of the oil bodies was investigated. Oil bodies in hemp seeds appeared spherical and sporadically distributed in the cell, with diameters of 3 to 5 μm. CLSM images of isolated oil bodies revealed the uniform distribution of phospholipids and proteins at their interface. Polyunsaturated fatty acids were predominant in the lipid fraction and linoleic acid accounted for ≈61% of the total fatty acids. The SDS-PAGE analysis of washed and purified oil bodies revealed major bands at 15 kDa and 50–25 kDa, which could be linked to membrane-specific proteins of oil bodies or extraneous proteins. The colloidal stability of oil bodies in different pH environments indicated that the isoelectric point was between pH 4 and 4.5, where oil bodies experienced maximum aggregation. Changes in the ionic strength decreased the interfacial charge density of oil bodies (ζ-potential), but it did not affect their mean particle size. This suggested that the steric hindrance provided by membrane-specific proteins at the interface of the oil bodies could have prevented them from flocculation at low interfacial charge density. The results of this study provide new tertiary knowledge on the structure, composition, and colloidal properties of oil bodies extracted from hemp seeds, which could be used as natural emulsions or lipid-based delivery systems for food products.

Effect of simulated saliva components on the in vitro digestion of peanut oil body emulsion

The digestion properties of natural oil bodies (OBs) are very important to their potential applications such as traditional fat replacement or bioactive delivery systems. However, study on the complete digestion behaviours of OBs has not been reported yet. In this paper, peanut OBs were extracted by an aqueous medium method, and their digestion behaviour was studied using completed in vitro oral-gastric-intestinal digestion simulation. In particular, the effects of saliva components, mainly α-amylase and mucin, on the digestion of the peanut OBs were systematically investigated. The OB emulsion microstructure, average particle size d_4,3, ζ-potential, and surface protein compositions during oral, gastric and intestinal digestion, and the free fatty acid (FFA) release rate of the peanut OBs during intestinal digestion were determined. Interestingly, it was revealed from both the periodic acid-Schiff staining technique and the confocal laser microscopy characterization that glycosidic bonds exist on the surface of the peanut OBs, though how they were produced was unknown. The results from the digestion measurements showed that α-amylase in saliva can break the glycosidic bonds in oral digestion, promoting the digestion of the OBs in the gastric and intestinal environments. Saliva mucin caused bridging flocculation of OBs by electrostatic attraction in the gastric tract, and depletion flocculation of OBs in the intestinal tract. The former hindered the fusion of oil droplets, and the latter promoted FFA release rate by increasing the contacting surface area of OBs with bile salts.

Glycosidic bonds exist on the surface of OBs, and α-amylase in saliva breaks the glycosidic bonds, promoting gastrointestinal digestion of OBs.

Preliminary Evaluation of Supercritical Carbon Dioxide Extracted Dabai Pulp Oleoresin as a New Alternative Fat

There has been growing interest among food scientists in producing a toxin-free fat as an end product with varying physical or nutritional properties of interest to the food industry. Oleoresin is a rich source of bioactive compounds which consumers can easily add to a large variety of food. Dabai (Canarium odontophyllum) pulp oleoresin (DPL) was extracted using supercritical carbon dioxide (SC-CO2) extraction, a green extraction technology. This study investigates the quality of SC-CO2 extracted DPL in discovering its potential as a new alternative fat. The extraction experiment was carried out at a pressure of 40 MPa and a temperature of 40 °C. DPL is a saturated fatty acid (SFA)-rich fat due to its high SFA composition (47.72 ± 0.01%). In addition, the low content of peroxide value (PV) (5.60 ± 0.09 mEq/kg) and free fatty acids (FFA) (3.40 ± 0.03%) indicate the quality and stability of DPL for various applications besides food consumption. DPL also has a low slip melting point (SMP) (20.20 ± 0.03 °C), and HPLC-FID revealed that DPL contained 0.13 ± 0.02 mg/100 g of vitamin E (α-tocopherol), indicating its potential application as a solid fat with a bioactive compound. This present work demonstrates the possible prospect of DPL in the formulation of end products for food industries.

Optimization of the extraction conditions and dermal toxicity of oil body fused with acidic fibroblast growth factor (OLAF)

INTRODUCTION

Oil body (OB), a subcellular organelle that stores oil in plant seeds, is considered a new transdermal drug delivery system. With the increasing understanding of the OB and its main protein (oleosin), numerous studies have been conducted on OB as "carrier" for the expression of exogenous proteins. In our previous study, oil body fused with aFGF (OLAF) was obtained using a plant oil body expression system that had been preliminarily proven to be effective in accelerating the healing of skin wounds. However, no dermal toxicological information on OLAF is available.

OBJECTIVE

To ensure the dermal safety of OLAF, a series of tests (the acute dermal toxicity test, 21-day repeat dermal toxicity test, dermal irritation test and skin sensitisation test) were conducted after optimising the extraction protocol of OLAF.

MATERIALS AND METHODS

To improve the extraction rate of OLAF, response surface methodology (RSM) was first employed to optimise the extraction conditions. Then, Wistar rats were exposed to OLAF (400 mg·kg^-1 body weight) in two different ways (6 hours/time for 24 hours and 1 time/day for 21 days) to evaluate the acute dermal toxicity and 21-day repeated dermal toxicity of OLAF. In the acute dermal toxicity test, clinical observations were conducted to evaluate the toxicity, behaviour, and health of the animals for 14 consecutive days. Similarly, the clinical signs, body weight, haematological and biochemical parameters, histopathological changes and other indicators were also detected during the 21 days administration. For the dermal irritation test, single and multiple doses of OLAF (125 mg·kg^-1 body weight) were administered to albino rabbits for 14 days (1 time/day). The irritation reaction on the skin of each albino rabbit was recorded and scored. Meanwhile, skin sensitisation to OLAF was conducted using guinea pigs for a period of 28 days.

RESULTS

Suitable extraction conditions for OLAF (PBS concentration 0.01, pH of PBS 8.6, solid-liquid ratio 1:385 g·mL^-1) were obtained using RSM. Under these conditions, the extraction rate and particle size of OLAF were 7.29% and 1290 nm, respectively. In the tests of acute dermal toxicity and 21-day repeated dermal toxicity, no mortality or significant differences were observed in terms of clinical signs, body weight, haematological parameters, biochemical parameters and anatomopathological analysis. With respect to the dermal irritation test and skin sensitisation test, no differences in erythema, oedema or other abnormalities were observed between treatment and control groups on gross and histopathological examinations.

CONCLUSIONS

The results of this study suggest that OLAF does not cause obvious toxicity, skin sensitisation or irritation in animals.

Effects of preheat treatments on the composition, rheological properties, and physical stability of soybean oil bodies

This study investigated the effects of preheat treatments on the composition, rheological properties, and the physical stability of soybean oil bodies and examined the stability of coffee containing those oil bodies. Three preheat treatment methods were compared, including heating (at 65, 75, and 85 °C for 30 min) of raw soymilk, high-pressure steam heating (at 110, 120, and 130 °C for 10 s, ultra high temperature [UHT] treated) of dry soybeans, and milling of soaked soybeans in boiling water. Three UHT samples showed the highest oil body yields (13.59 to 13.87%) and protein yield (2.47 to 3.03%), while oil content in extracts was the lowest (30.97 to 46.25%). Soymilk heated at 65 or 75 °C for 30 min showed high oil body extraction yields (13.38 and 11.46%) and the highest oil extraction yields (6.38 to 8.38%) among all the samples. Three UHT samples had a higher average particle size and higher apparent viscosity compared with those of all the other samples. The results from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and particle size distribution suggested heat treatment at 65 to 85 °C just lead to the partially denaturation and unfolding of storage protein instead of severe aggregation, while UHT (samples 5, 6, and 7) could lead to large amount soluble aggregates within oleosins and storage proteins via disulfide bonds. The diluted emulsion with 12% fat content remained stable during a 15-day storage period at 4 °C. The coffee stability of the diluted oil body emulsion indicated high oleosins and low storage protein content in the oil body was a benefit for the coffee stability. PRACTICAL APPLICATION: Soybean oil bodies are natural sources of pre-emulsified oil derived from soybean and can be dispersed in an aqueous medium to form a stable emulsion system. This study provides the foundation for the preparation and application of soybean oil bodies with differing emulsion stabilities and extraction yields in the food industry.

Combination of Alcalase 2.4 L and CaCl2 for aqueous extraction of peanut oil

The combined application of CaCl₂ and Alcalase 2.4 L to the aqueous extraction process of peanuts was evaluated as a method to destabilize the oil body (OB) emulsion and improve the oil yield. After adding 5 mM CaCl₂ , the oil yield was reached to 92.0% which was similar with that obtained using Alcalase 2.4 L alone, and the required enzyme loading was decreased by approximately 60 times. In addition, the demulsification mechanism during aqueous extraction process was also investigated. Particle size and zeta-potential measurements indicated that the stability of the peanut OB emulsion dramatically decreased when CaCl₂ was added. Under these conditions, the demulsification of Alcalase 2.4 L performed was more efficiently. SDS-PAGE results showed that adding CaCl₂ changed the subunit structure of the peanut OB interface proteins and promoted the cross-linking among the arachin Ara h3 isoforms, resulting in unstable emulsions.

The effect of monovalent (Na+, K+) and divalent (Ca2+, Mg2+) cations on rapeseed oleosome (oil body) extraction and stability at pH 7

Oleosomes are storage vehicles of TAGs in plant seeds. They are protected with a phospholipid-protein monolayer and extracted with alkaline aqueous media; however, pH adjustment intensifies the extraction process. Therefore, the aim of this work was to investigate the extraction mechanism of rapeseed oleosomes at pH 7 and at the presence of monovalent and divalent cations (Na⁺, K⁺, Mg²⁺_, and Ca⁺²). The oleosome yield at pH 9.5 was 64 wt%, while the yield at pH 7 with H₂O was just 43 wt.%. The presence of cations at pH 7, significantly enhanced the yield, with K⁺ giving the highest yield (64 wt.%). The cations affected the oleosome interface and their interactions. The presence of monovalent cations resulted in aggregation and minor coalescence, while divalent cations resulted in extensive coalescence. These results help to understand the interactions of oleosomes in their native matrix and design simple extraction processes at neutral conditions.

Improving the Stability of Oil Body Emulsions from Diverse Plant Seeds Using Sodium Alginate

In this study, peanut, sesame, and rapeseed oil bodies (OBs) were extracted by the aqueous medium method. The surface protein composition, microstructure, average particle size d 4 ,   3 , ζ-potential of the extracted OBs in aqueous emulsion were characterized. The stability of the OB emulsions was investigated. It was found that different OB emulsions contained different types and contents of endogenous and exogenous proteins. Aggregation at low pHs (<6) and creaming at high pHs (7 and 8) both occurred for all of three OB emulsions. Sodium alginate (ALG) was used to solve the instability of OB emulsions under different conditions-low concentration of ALG improved the stability of OB emulsions below and near the isoelectric point of the OBs, through electrostatic interaction. While a high concentration of ALG improved the OB emulsion stability through the viscosity effect at pH 7. The OB emulsions stabilized by ALG were salt-tolerant and freeze-thaw resistant.

Peanut Oil Body Composition and Stability

This study was aimed to assess the effect of membrane structure on the stability of peanut oil bodies extracted by enzyme-assisted extraction. The influence of pH, NaCl concentration, and temperature on the physicochemical properties of peanut oil bodies was characterized using ζ-potential and particle size. The results indicated that the peanut oil bodies had strong stability (ζ-potential, >20 mV) at pH values away from the isoelectric point (pH 4.8), at a low salt concentration (NaCl concentration, <10 mM), and in a certain temperature range (35 to 55 °C). The stable structure of the oil body was closely related to its structure. Phospholipids, along with membrane proteins, were major components of the oil body membrane. Therefore, the phospholipid composition and content were measured and the types of membrane proteins of the oil bodies were identified. The results showed that phosphatidylcholine and phosphatidylserine were major components of the oil body phospholipids. Two-dimensional electrophoresis showed that the oil bodies contained both intrinsic proteins and extrinsic proteins, which might play an important role in the stability of oil bodies during enzyme-assisted extraction processing.

Expression of a functional recombinant vascular endothelial growth factor 165 (VEGF165) in Arabidopsis thaliana

Objective

Targeting the protein of interest to a particular tissue to achieve high-level expression is an important strategy to increase expression efficiency. The use of the plant seed oil body as a bioreactor can not only increase the amount of target protein, but also reduce the cost of downstream processing.

Methods

VEGF165 was expressed in Arabidopsis thaliana seeds via oilbody fusion technology. The pKO-VEGF165 vector was construted and transformed into A. thaliana seeds. T3 transgenic seeds was detected by SDS-PAGE and western blot methods. The cell activity was tested by MTT methods.

Result

The phaseolin promoter was used to drive seed-specific expression of the VEGF165 gene in transgenic A. thaliana. The coding region of VEGF165 was fused to the Arabidopsis oleosin sequence to target the protein to the oil bodies in the seeds of transgenic plants. The T-DNA region of recombinant plasmid pKO-VEGF165 was shifted to A. thaliana seeds via the floral-dip method. Protein was analyzed by electrophoresis and protein hybridization analyses. Finally, MTT assays showed that the oleosin-VEGF165 fusion protein played a part in the proliferation of HUVEC cells in vitro.

Conclusion

Oleosin-VEGF165 was successfully expressed and it had stimulated HUVEC cell proliferation activity.

Genotoxicity of titanium dioxide nanoparticles and triggering of defense mechanisms in Allium cepa

Titanium dioxide nanoparticles (TiO2NPs) are widely used and may impact the environment. Thus, this study used a high concentration of TiO2NP (1000 mg/L) to verify the defense mechanisms triggered by a plant system - an indicator of toxicity. Furthermore, this study aimed at completely characterizing TiO2NP suspensions to elucidate their toxic behavior. TiO2NPs were taken up by meristematic cells of Allium cepa, leading to slight inhibition of seed germination and root growth. However, severe cellular and DNA damages were observed in a concentration-dependent manner (10, 100, and 1000 mg/L). For this reason, we used the highest tested concentration (1000 mg/L) to verify if the plant cells developed defense mechanisms against the TiO2NPs and evaluated other evidences of TiO2NP genotoxicity. Nucleolar alterations and plant defense responses (i.e., increased lytic vacuoles, oil bodies and NP phase change) were observed in meristematic cells exposed to TiO2NP at 1000 mg/L. In summary, TiO2NPs can damage the genetic material of plants; however, plants displayed defense mechanisms against the deleterious effects of these NPs. In addition, A. cepa was found to be a suitable test system to evaluate the cyto- and genotoxicity of NPs.

Protein analysis reveals differential accumulation of late embryogenesis abundant and storage proteins in seeds of wild and cultivated amaranth species

BACKGROUND

Amaranth is a plant naturally resistant to various types of stresses that produces seeds of excellent nutritional quality, so amaranth is a promising system for food production. Amaranth wild relatives have survived climate changes and grow under harsh conditions, however no studies about morphological and molecular characteristics of their seeds are known. Therefore, we carried out a detailed morphological and molecular characterization of wild species A. powellii and A. hybridus, and compared them with the cultivated amaranth species A. hypochondriacus (waxy and non-waxy seeds) and A. cruentus.

RESULTS

Seed proteins were fractionated according to their polarity properties and were analysed in one-dimensional gel electrophoresis (1-DE) followed by nano-liquid chromatography coupled to tandem mass spectrometry (nLC-MS/MS). A total of 34 differentially accumulated protein bands were detected and 105 proteins were successfully identified. Late embryogenesis abundant proteins were detected as species-specific. Oleosins and oil bodies associated proteins were observed preferentially in A. cruentus. Different isoforms of the granule-bound starch synthase I, and several paralogs of 7S and 11S globulins were also identified. The in silico structural analysis from different isoforms of 11S globulins was carried out, including new types of 11S globulin not reported so far.

CONCLUSIONS

The results provide novel information about 11S globulins and proteins related in seed protection, which could play important roles in the nutritional value and adaptive tolerance to stress in amaranth species.

Supercritical Fluid Extraction of Berry Seeds: Chemical Composition and Antioxidant Activity

The influence of supercritical fluid extraction (SFE) and solvent extraction of oils from cloudberry, bilberry, and black currant seeds on the yield, chemical properties, and recovery of antioxidant compounds was investigated. SFE was performed for 1 h at 350 bar and at 50°C and 80°C. Fatty acids, vitamin E, carotenoids, and free radical-scavenging activity (DPPH) were assayed. SFE at 80°C resulted in higher oil yields for cloudberry and black currant seeds. The oils were rich in polyunsaturated fatty acids (PUFAs) (66.8%–75.9% w/w), with high percentages of linoleic and α-linolenic acids. The black currant seed extracts had the highest concentrations of vitamin E (range, 113.0–241.8 mg/100 g oil) and carotenoids (range, 11.5–32.3 mg/100 g oil) and the highest antioxidant activity. The cloudberry seed oils also had high antioxidant content and activity. These findings indicate the potential of SFE for the recovery of PUFA and antioxidant compounds in berry by-products.

Efficient salt-aided aqueous extraction of bitter almond oil

BACKGROUND

Salt-aided aqueous extraction (SAAE) is an inexpensive and environmentally friendly method of oil extraction that is influenced by many factors. In the present study, we investigated the effect of SAAE on bitter almond oil yield.

RESULTS

This study used sodium bicarbonate solution as extraction solvent and the optimal extraction parameters predicted by Box-Behnken design (i.e., concentration of sodium bicarbonate, 0.4 mol L^-1 ; solvent-to-sample ratio, 5:1; extraction temperature, 84 °C; extraction time, 60 min), for oil recovery of 90.9%. The physiochemical characteristics of the extracted oil suggest that the quality was similar to that of the aqueous enzymatic extracted oil. Moreover, the content of hydrocyanic acid (HCN) in bitter almond oil was found to be less than 5 mg kg^-1 , which was lower compared to that obtained by other reported methods. Results of microanalysis indicated that SAAE led to significant improvement in oil yield by allowing the release of oil and decreasing the emulsion fraction. Therefore, extraction of bitter almond oil by SAAE is feasible.

CONCLUSION

These results demonstrate that extraction of bitter almond oil by SAAE based on the salt effect is feasible on a laboratory scale. © 2017 Society of Chemical Industry.