Effect of argan kernel storage conditions on argan oil quality

In the present study, we investigated the relationships between storage conditions of argan kernels and argan oil quality over a 1‐year period. Argan kernels were packaged in black or white bags. Kernels in black bags were stored at room temperature (RT) while kernels in white bags were stored either at RT or at 4°C. Quality parameters periodically monitored over the 12 months were peroxide and acid value, oil yield, moisture content, UV absorption, and fatty acid composition. Whereas light had no impact on argan oil quality, only argan kernel storage at 4°C allowed a perfect preservation of argan oil quality after 1 year. Practical applications: In the present study we have established that solar light does not damage argan kernels in such a way that it could alter argan oil quality, and that argan kernels can be stored for up to 1 year at 4°C without alteration of argan oil quality. If stored at RT, argan kernels should be used within 10 months to prepare edible argan oil.     

Argan oil and other argan products: Use in dermocosmetology

Argan oil is of food or cosmetic (INCI name: Argania spinosa kernel oil) grade. During the past 15 years cosmetic argan oil, as beauty oil or cosmetic ingredient, has become one of the major actors in the dermocosmetic field. Beauty argan oil is produced by cold‐pressing argan‐fruit kernels. As a cosmetic ingredient, argan oil is produced by solvent‐assisted extraction of the finely crushed kernels. Enriched‐argan oil which is produced by distillation of cosmetic argan oil can be supplemented with antioxidants. Hence, it presents an even better cosmetic potential. Argan fruit pulp and argan leaves also contain proteins, peptides, saponins and other chemicals presenting highly interesting dermocosmetics. Therefore, the argan tree (A. spinosa) is sometimes nicknamed A. cosmetosa. We comprehensively review the current knowledge (literature and patent) related to argan oil and argan tree products in the dermocosmetic domain.     

Aroma‐Relevant Volatile Compounds as Markers for the Sensory Quality of Argan Oil

The aim of the present work is to identify and characterize the most important aroma active compounds of argan oil from unroasted and roasted argan almonds as well as roasted almonds obtained from goat‐digested fruits by dynamic headspace GC and GC‐olfactometry with aroma dilution analysis to classify samples from the market according to their processing. While fresh ground argan almonds are characterized by only seven aroma active compounds, in argan oil from unroasted and roasted almonds, 22 and 35 aroma active compounds are found, respectively. As a result of the roasting process, 14 aroma active compounds with dilution factors >64 are detected in the oil by GC‐olfactometry. 17 aroma active compounds show significant differences between the three different argan oil qualities. These compounds are used to differentiate the quality of argan oil from the market. Practical Application: Argan oil belongs to the high‐price oils on the market but sometimes the sensory quality of the oil contradicts the positive image that has been built up for oil by unpleasant cheese‐like and fusty sensory attributes. Although some information about the composition of the volatile compounds of cold‐pressed argan oil from unroasted and roasted kernels is available, the knowledge about compounds that are typical for the aroma of argan oil is important in order to develop analytical methods for the classification of different argan oil qualities. This reduces the work for a panel group that is often time and labor consuming and sometimes the results are not reliable. The present paper demonstrates which volatile compounds show significant differences between argan oil from unroasted and roasted argan almonds as well as roasted almonds obtained from goat‐digested fruits allowing a differentiation of these oils.     

Characterization of artisanally and semiautomatically extracted argan oils from Morocco

The present study was conducted to know the possible influence of the seed treatment, method of extraction and geographical origin on the quality and chemical composition of argan oil. Artisanally and semiautomatically extracted argan oils, from roasted and unroasted seeds, from interior and coast areas, were studied. The quality parameters analyzed were acid value, peroxide value, K₂₃₂ and K₂₇₀, triacylglycerols and fatty acid composition, polar compounds, total phenols, tocopherol content and oil stability index (OSI). Seed treatment and extraction method showed a higher influence on quality parameters than geographical area; the quality parameters of the different oils were discussed. The total phenolic content in all analyzed samples was lower than 10 ppm. γ‐Tocopherol was the major tocopherol (84.4–86.4%) with a high contribution to the total tocopherol content (383–485 ppm). The OSI of the argan oil samples were well correlated (R = 0.97) with the tocopherol contents. The argan oil samples obtained from roasted seeds presented higher stability (26–38 h) than the oils from unroasted seeds (16–32 h).     

Pentacyclic triterpenic acids from Argania spinosa

This work reports for the first time the presence of pentacyclic triterpenic acids in Argania spinosa. By solid/liquid extraction with absolute ethanol and GC‐FID analysis, we report that ursolic acid is the major triterpene in the leaf and fruit of argan (0.10–0.44% DW), followed by significant amounts of oleanolic acid (0.05–0.19% DW). Their contents in the leaf were four times higher than in the fruit. Minor levels of betulinic and maslinic acids were also determined in the fruit pulp. Our results suggest that the developmental stage of the plant organ and the environmental conditions modulate the biosynthesis of triterpenic acids in argan. Advanced stages of ontogeny and severe climatic conditions induced a selective production of lupenyl and ursanyl structures. Argan fruits and leaves constitute interesting raw materials for the obtaining of ursolic and oleanolic acids that are strongly demanded by the functional food and pharmaceutical industries. The utilization of dry pulp of argan fruits, a by‐product of the argan oil industry, for the obtaining of new triterpene‐based formulations of high added value would increase the profitability of these crops and might help to guarantee the survival of the A. spinosa forests in the long term. Practical applications: Argan fruits and leaves constitute interesting raw materials for obtaining ursolic and oleanolic acids. Morocco accumulates every year more than 44 500 tons of dry fruit pulp as a by‐product of the argan oil industry. The utilization of this biomass for the obtaining of bioactive compounds of high added value that could be used in the design of new functional food and drugs would help to increase the profitability of the argan crops and represent an intelligent manner of contributing to the A. spinosa survival.     

Controlling Argan Seed Quality by NIR

The suitability of using visible/near infrared spectroscopy (Vis/NIR), as a rapid and non‐destructive technique for monitoring the quality of argan seeds (Argania spinosa Skeels) was studied. The analyzed parameters were the fatty acid composition of argan seed oil, seed moisture content, seed oil content and oil stability index (OSI). The ratio between major unsaturated and saturated fatty acids (U/S) during the oxidation assay at constant temperature was studied. Values from infrared drying were used as a laboratory reference for the moisture. Argan seed oil content was determined by Soxhlet extraction. A fatty acid analysis was carried out by gas chromatography and the OSI was determined by the Rancimat test. Predictive models of argan seed moisture, ratio U/S and OSI showed good accuracy. Therefore, Vis/NIR measurements can be used for controlling several argan seed quality parameters. This procedure might be of interest to the argan oil industry, which is currently in the process of modernization and expansion.     

Argan oil-in-water emulsions: Preparation and stabilization

We prepared stable oil-in-water emulsions of argan oil with two different types of mixtures of nonionic emulsifiers. Three different types of oil (Israeli argan oil, Moroccan argan oil, and soybean oil) were emulsified with mixtures of Span 80 and Tween 80. The optimum HLB value for argon oil was 11.0 (±1.0). The argan oil-in-water emulsions were stable for more than 5 mon at 25°C. Synergistic effects were found in enhancing stability of emulsions prepared with sucrose monostearate. The origin of the oil and the internal content of natural emulsifiers, such as monoglycerides and phospholipids, have a profound influence on its interfacial properties and on the stability of the argan oil-in-water emulsions.     

Influence of physical pretreatments of sheanuts (Vitellaria paradoxa Gaertn.) on butter quality

Shea butter, usually extracted from kernels of Vitellaria paradoxa Gaertn. by rural women in Sub‐Saharran Africa, has multiple traditional and industrial uses. Traditional processing methods are not standardized and often lead to the production of poor quality butter, which attract low market prices. The aim of this work was to study the different pretreatments locally applied to sheanuts during processing in order to identify those that can affect butter quality. The effect of cooking, soaking as well as drying on the amount of butter extracted and its minor constituents were investigated. All these pretreatments significantly affected oil quality. The effect of soaking of the kernels on improving oil extraction yields (55%) was comparable to that of kernels digested with α‐amylase, acid protease, cellulase/hemicellulase, pectinase, and glucanase enzymes before oil extraction reported in the literature. Drying had a significant negative effect on tocopherol contents of the oil. However, residual amounts of tocopherols in the oil after drying were high enough to suggest that it may still confer anti‐oxidant activities. Soaking, cooking, and drying are important pretreatments involved in the production of shea butter locally that need to be standardized in order to produce better quality butter. Practical applications: In this work, we carried out scientific analysis of methods already used by rural women to process shea fruits into shea butter. This work should be useful for establishing processing conditions for obtaining good quality shea butter.     

Detection of Argan Oil Adulteration Using Quantitative Campesterol GC-Analysis

Detection of edible oil adulteration is of utmost important to ensure product quality and customer protection. Campesterol, a sterol found in seed oils, represents less than 0.4% of argan oil total sterol content. Quantitative analysis of campesterol by gas chromatography of argan oil and of a mixture of argan oil and readily commercially available vegetable oils, consecutively with sterol separation, was carried out. Our study clearly demonstrated that determination of the campesterol level in argan oil (or oil presented as argan oil) can be proposed as the major analysis method to assess unambiguously argan oil purity up to 98%.     

Determination of polyphenols,tocopherols, and antioxidant capacity in virgin argan oil (Argania spinosa,Skeels)

This study establishes data on polyphenols, tocopherols, and antioxidant capacity (AC) of virgin argan oil. A total of 22 samples from Morocco were analyzed. Total polyphenol content ranged between 6.07 and 152.04 mg GAE/kg. Total tocopherols varied between 427.0 and 654.0 mg/kg, being γ‐tocopherol the major fraction (84.68%); α‐, β‐, and δ‐tocopherols represent 7.75, 0.33, and 7.29%, respectively. No influence of oil extraction method on total tocopherols was observed. The AC of argan virgin oils determined by the ABTS method in n‐hexane oils dilution ranged between 14.16 and 28.02 mmol Trolox/kg, and by the ABTS, DPPH, and FRAP methods in methanolic oil extracts between 2.31–14.15, 0.19–0.87, and 0.62–2.32 mmol Trolox/kg, respectively. A high correlation was found between ABTS and DPPH methods applied to a methanolic oil extract. Virgin argan oil presents a higher polyphenol and tocopherol content, and total AC than other edible vegetable oils.     

Preparation and characterization of highly stable monodisperse argan oil‐in‐water emulsions using microchannel emulsification

Argan oil is well known for its nutraceutical properties. Its specific fatty acid composition and antioxidant content contribute to the stability of the oil and to its dietetic and culinary values. There is an increasing interest to use argan oil in cosmetics, pharmaceutics, and food products. However, the formulation of highly stable emulsions with prolonged shelf life is needed. In this study, argan oil‐in‐water (O/W) emulsions were prepared using microchannel (MC) emulsification process, stabilized by different non‐ionic emulsifiers. The effects of processing temperature on droplet size and size distribution were studied. Physical stability of argan O/W emulsions was also investigated by accelerated stability testing and during storage at room temperature (25 ± 2°C). Highly monodisperse argan O/W emulsions were produced at temperatures up to 70°C. The obtained emulsions were physically stable for several months at room temperature. Furthermore, emulsifier type, concentration, and temperature were the major determinants influencing the droplet size and size distribution. The results indicated that a suitable emulsifier should be selected by experimentation, since the interfacial tension and hydrophilic–lipophilic balance values were not suitable to predict the emulsifying efficiency. Practical applications: MC emulsification produces efficiently monodisperse droplets at wide range of temperatures. The findings of this work may be of great interest for both scientific and industrial purposes since highly stable and monodisperse argan oil‐in‐water emulsions were produced which can be incorporated into food, cosmetic, or pharmaceutical formulations.     

Tree Nut Oils: Chemical Profiles,Extraction, Stability,and Quality Concerns

Tree nuts are globally consumed. Their kernels are calorie‐rich, nutrient‐dense foods and contain several bioactive and health‐promoting components. While some nut crops have expanded through the world since ancient times (almond, hazelnut, walnut), more recently, there has been a parallel development of underexploited promising species (Brazil nut, macadamia, pecan). Nut kernels have high lipid content, ranging from 40% to 80% depending on nut species and varieties. In general, nut oils contain significant proportions of nutritionally and medicinally desirable fatty acids and nutraceutical compounds (sterols, tocopherols, and other phenolics). A considerable genetic variability in oil content and composition is present in nut genetic resources worldwide. This suggests the possibility of different breeding lines focused to enhance oil yields, chemical and quality traits. Regarding extraction, screw‐pressing is suitable to achieve high oil recovery and good quality standards, but seed materials should be conditioned appropriately. Seed moisture content and pressing temperature appear as key variables to enhance oil recovery. This article presents an overview on chemical profiles, mechanical extraction, and quality concerns of oils from the most widely produced tree nut crops. The revision is also aimed at identifying areas where knowledge is insufficient and to set priorities for further research. Practical applications: The review updates and increases knowledge about oils from tree nut genetic resources, encompassing genetic variability and environmental effects on oil yield and compositional traits. It also analyzes findings regarding oil extraction and provides useful insights to establish better conditions for achieving sustainable oil yields and good quality standards.     

A novel process for extraction of tea oil from Camellia oleifera seed kernels by combination of microwave puffing and aqueous enzymatic oil extraction

The objective of this study was to extract the oil from Camellia oleifera seed kernels by aqueous enzymatic oil extraction (AEOE). We describe a novel process for extraction of tea oil preceded by tea saponin extraction from C. oleifera seed kernels. The extraction efficiency obtained with microwave‐assisted extraction (MAE) is very high, which the recovery yield is up to 83% in 30 s and the saponins in camellia seed kernels can be completely removed by the second MAE. Moreover, an important step in the process development has been the pretreatment by microwave puffing of camellia seed kernel residues followed by AEOE increased oil extraction yield from 53% to 95%, which will is comparable to hexane oil extraction yields from plant materials.     

Optimization of industrial‐scale deodorization of high‐oleic sunflower oil via response surface methodology

Optimization of industrial‐scale deodorization of high‐oleic sunflower oil (HOSO) via response surface methodology is presented in this study. The results of an experimental program conducted on an industrial‐scale deodorizer were analyzed statistically. Predictive models were derived for each of the oil quality indicators (QI) in dependence on the studied variable deodorization process parameters. The deodorization behavior of some minor components was analyzed on a pilot‐scale deodorizer. For comparison, a similar experimental program was also performed on the laboratory‐scale. The results of this study demonstrate that optimization of the deodorization process requires a suitable compromise between often mutually opposing demands dictated by different oil QI. The production of HOSO with top‐quality organoleptic and nutritional values (high tocopherol and phytosterol contents and low free and trans fatty acid contents) and high oxidative stability demands deodorization temperatures in the range between 220 and 235 °C and a total sparge steam above 2.0% (wt/wt in oil). The response surface methodology provides the tools needed to identify the optimum deodorization process conditions. However, the laboratory‐scale experiments, while showing similar response characteristics of QI in dependence on the process parameters and thus helpful as a guide, are of limited value in the optimization of an industrial‐scale operation.     

Chemical Composition,Physical Properties,and the Oxidative Stability of Oil Bodies Extracted From Argania spinosa

Oil bodies (OB) were extracted from argan kernels using an aqueous extraction method. The composition of OB revealed its lipid profile, which had a high content of stearic and palmitic acid. Besides, evidence suggested an association between OB and tocopherols. The physical properties of argan OB (AOB) showed that their size was around 1.9 μm and the ζ‐potential went from +17.7 mV at pH 2.0 to ?32.25 mV at pH 8, with an isoelectric point around pH 5.1. OB were stable and small at pH 2.0, 7.0, and 8.0 but large near the pI. Additionally, AOB were stable against aggregation/coalescence even in high salt concentrations, and also against thermal processing (95 °C) with only a change in their interfacial properties. AOB emulsion showed interesting oxidative stability at different storage temperatures and heat treatment. Heat treatment and storage at low temperature preserved oleosins from degradation by the endogenous enzyme, and H‐oleosin 15 kDa resisted hydrolyzation even at a high storage temperature for 2 weeks.     

Cherry leafroll virus: Impact on olive fruit and virgin olive oil quality

We performed a survey on the yield, quality, and chemical characteristics of virgin olive oils from two olive varieties in Croatian Istria: Frantoio and Ascolana tenera, on Cherry leafroll virus‐infected and virus‐noninfected trees and on two harvest dates. Free acidity, peroxide value, specific spectrophotometric absorptions at 232 and 270 nm, fatty acid composition, total phenols, o‐diphenols, oil color, and pigments were determined. Infected olives had lower oil yield and maturity index versus healthy ones. Oils from infected fruits had significant lower value of K₂₃₂ and K₂₇₀ and very elevated total phenols content compared to those obtained from healthy olives. Infected Frantoio gave a lower content of o‐diphenols than the healthy ones, which is in contrast to infected Ascolana that had higher values. The aim of this study is to determine the chemical changes in virgin olive oils from healthy and infected trees related to virus influence. According to our knowledge, this is the first survey on the possible influence of viruses on olive fruits, oil yield, and virgin olive oil quality. Practical applications : There are only few papers which analyze the influence of viruses on crops (especially influence on wine quality) and their effects on yield or other agronomic parameters. This work evaluates for the first time the impact of Cherry leafroll virus on the quality of virgin olive oil obtained from Frantoio and A. tenera varieties in terms of basic parameters related to the hydrolitic and oxidative status, content in antioxidant compounds, and in pigments as well as in fatty acid composition.     

Effect of roasting on oxidative and tocopherol stability of walnut oil during storage in the dark

The effect of roasting on the oxidative stability of oil from walnut (Juglans sinensis Dode) was investigated by observing changes in the characteristics of oils from unroasted and roasted kernels during storage in the dark at 60°C. Walnut kernels were roasted at 160°C for 15 min prior to oil extraction with the solvent, hexane. Roasting of kernels increased the peroxide value (POV) and conjugated dienoic acid (CDA) value of the oil. The rate of increase in the POV was significantly lower in roasted than in the unroasted walnut oil during storage at 60°C (1.90 vs. 1.06 and 4.45 vs. 3.55 meq/kg/day during induction period (IP) and post‐IP, respectively). Roasting of kernels significantly increased the IP of walnut oil from 0.89 to 3.39 days during storage. The total tocopherol content in roasted walnut oil was lower as compared to that in unroasted one (277.77 vs. 314.88 µg/g). However, the rate of degradation of total tocopherol during storage was lower in roasted walnut oil compared to unroasted one (1.18 vs. 2.17%/day), which showed that the tocopherol retention was higher in roasted walnut oil. These results indicate that roasting of kernels increased the oxidative and tocopherol stability of oil during storage in the dark.     

Characterization of Extra Virgin Olive Oil from Southern Brazil

Six olive oils extracted from the cultivars Arbequina, Arbosana, Coratina, Frantoio, Koroneiki, and Picual from 2017 and 2018 harvests, cultivated in Pinheiro Machado, Rio Grande do Sul, Brazil, are evaluated for standard oil composition parameters and bioactive constituents (pigments, tocopherols, and phenolic compounds). Multivariate principal component analysis (PCA) and univariate ANOVA and Fisher's LSD test are used to verify the effect of cultivar and harvest year on oil composition. Olive oil composition met extra virgin olive oil (EVOO) standard parameters and is influenced by both cultivar and harvest year. EVOO produced in 2018 has greater chlorophyll, caffeic acid, ligstroside aglycone, hydroxyoleuropein aglycone, syringic acid, and hydroxytyrosol acetate contents than the EVOOs from 2017. Linoleic acid, ferulic acid, ligstroside aglycone, and hydroxytyrosol acetate are the variables whose contents most contributed to the differentiation of oils by cultivar in both harvest years. Chemical characterization analyses allow for the differentiation of oil composition based on harvest year and cultivar. Metabolic quality data obtained here support the establishment of a local EVOO profile and the compounds that most contributed to treatment differentiation may serve as markers that can be utilized in determining origin, cultivar, and harvest year. Practical Applications: Olive production in Brazil is recent and is based on European cultivars which have not been bred for the local environmental conditions. Therefore, the measurement of olive oil metabolic quality will determine cultivar adaptability to local edaphoclimatic conditions as well as assist in the establishment of a standard of identity for the product and promote the development of its market. Olive oil produced in Southern Brazil shows high quality, and is especially rich in phenolic compounds. Although harvest year influences oil composition, oil from both harvests meet EVOO standards and cultivar specific metabolic markers are observed. This study provides the foundation for olive producers in Southern Brazil to seek authentication of the geographical origin of olive oil.     

A Comparative Study on Response Surface Optimization of Supercritical Fluid Extraction Parameters to Obtain Portulaca Oleracea Seed Oil with Higher Bioactive Content and Antioxidant Activity Than Solvent Extraction

Portulaca oleracea (purslane) seed oil is a rich source of omega-6 and omega-3 fatty acids. Extraction of the purslane seed oil while preserving its high nutritive quality has been a challenge since conventional solvent extraction has many adverse effects on bioactive content. This study aims the optimization of purslane seed oil supercritical fluid extraction (SFE) conditions and to compare purslane seed oils obtained with SFE and conventional solvent extraction in terms of oil yield, along with the purslane seed oil quality and bioactive content. For this purpose, the SFE process parameters (pressure, temperature, static time, and dynamic time) are optimized for oil yield, omega-6, omega-3, and antioxidant activity using response surface methodology (RSM). Optimum SFE pressure, temperature, static time, and dynamic time levels are determined as 350 bar, 50 °C, 20 min, and 90 min, respectively. Oil yield and physicochemical quality properties of conventional solvent extract and SFE samples are determined and compared. Consequently, samples obtained via SFE and solvent extraction have similar quality properties. Distinctly, SFE allows an extraction with 5.6% higher total phenolic compound (TPC) and 33% higher antioxidant activity than solvent extraction. Practical Applications: In the study, the extraction of purslane oil using supercritical fluid extraction is optimized with different approaches. At optimum conditions, purslane oil is extracted and all physicochemical properties and the process efficiency (yield) are compared with the solvent-extracted samples. The results of this study make supercritical fluid extraction of purslane seed oil possible since all optimum operating conditions of a pilot-sized extractor are reported in the study. It is believed that the results provide a good starting point for industrial operations. Moreover, researchers also believe that research studies unveiling the new potential oil-bearing seeds are important to overcome the vegetable oil shortage that emerged this year.     

Palm kernel oil extraction - The malaysian experience

In direct screw pressing, kernels must undergo seed preparation steps of size reduction, flaking and steam conditioning prior to mechanical extraction. Mechanical wear and tear, maintenance expenses and electricity are the major costs. The direct solvent extraction process is used in larger plants. Production cost depends mainly on solvent loss and energy used in solvent recovery and pelletizing. However, oil recovery is more complete than in screw pressing. A third processing method uses pre-pressing followed by solvent extraction. The choice of process or machinery depends on capital investment, production cost, oil recovery and its value. Whether the higher investment and production cost incurred in solvent extraction is offset by the higher oil extraction rate needs to be determined. Strict quality control right from fruit processing to kernel extraction is necessary to ensure production of good quality oil and by-products. Malaysian palm kernel oil has proven to be of consistent quality, with narrow ranges in chemical characteristics. The palm kernel cake and pellets are important ingredients for animal feed.