Optimization of solvent extracted melon seed oil using RSM

Effect of roasting temperature and roasting duration on oil yield (OY) and quality of melon seed (Citrullus lanatus Thunb.) was studied using RSM. Five levels of roasting temperature (87.6, 100, 130, 160, and 172.4°C) and duration (12.9, 15, 20, 25, and 27.1 min) considered. Quality parameters determined were specific gravity (SG), color (CO), free fatty acid (FFA), and anisidine value (AV). Recorded range of OY, SG, CO, FFA, and AV were 44.0–67.5%, 0.9–1.0, and 13.1–94.0 abs, 1.7–5.3%, and 3.9–28.2 mg/L, respectively. The variables have significant effect (p<0.05) on all the responses with exception of SG. Coefficients of determination ($R^{2} $ ) of predictive equations for OY, CO, FFA, and AV were 0.79, 0.97, 0.95, and 0.95, respectively. Optimum roasting temperature and duration were 133.06°C and 20.19 min, respectively. These gave 63.5% OY, 0.9 SG, 13.1 abs CO, 1.7% FFA, and 3.4 mg/L AV. Practical applications: Melon seeds contain about 60% edible oil. Optimization of the process parameters (heating duration temperature) will enhance high OY with good quality. Models developed in this study can be useful for producers of oil extraction equipment and potential investors into commercial production of the oil.     

Heat treatment effects on extraction of roselle (Hibiscus sabdariffa L) seed oil

Fatty acid composition of roselle (Hibiscus sabdariffa L) seed oil was determined and oil extraction was optimized using RSM. Five levels of the variables, roasting duration (10, 15, 20, 25, and 30 min), and temperature (80, 90, 100, 110, and 120°C) were used. Oil yield (OY), free fatty acid (FFA), anisidine value (AV), specific gravity (SG), and stability were responses and determined using standard methods. Major fatty acids found were oleic acid (37.92%), linoleic (35.01%), palmitic (19.65%), and stearic (6.07%). Myristic (0.16), myristoleic (0.17), palmitoleic (0.56), arachidic (0.14), and eicosatrienoic (0.20) were minor fatty acids content. OY, FFA, AV, SG, and stability varied from 18 to 23%, from 0.56 to 4.11%, from 6.93 to 35.7 mg/L, from 0.90 to 0.95, and from 0.68 to 5.42%, respectively. The treatment had significant (p<0.05) effect on OY, AV, and SG. However, non‐significant effect of treatment was recorded on FFA and stability at 5% level of significance. The best desirability of 0.46 was achieved at roasting duration and temperature of 25 min and 110°C, respectively, which gave OY of 22%, initial FFA of 1.95%, AV of 31.2 mg/L, SG of 0.92, and stability of 2.67%. Practical applications: Roselle seed is a by‐product from the processing of roselle calyces. Reports from literature have shown that the seed contains about 20% edible health‐promoting oil. Research into effect of pre‐heat treatment on quality and quantity of oil extracted from roselle seed will serve as a guide in recommending optimum heating duration and temperature. The models developed in this study can be a working tool for producers of roselle oil extraction equipment and potential investors into commercial production of roselle oil. Output of this work may change the status of the seeds from a waste material to a valuable product.     

Effect of Roasting on Physicochemical Properties of Wild Almonds (Amygdalus scoparia)

Roasting enhances sensory quality of wild almonds (Amygdalus scoparia). The aim of the study was to evaluate the use of microwaves (480 W for 3 or 4 min) in roasting of wild almonds in comparison with traditional Spanish (165 °C for 20 min) and Iranian (soaking in 20 % NaCl in water for 30 min, drying at 60 °C for 2 h and roasting at 135 °C for 20 min) hot‐air processes. The influence of roasting wild almonds on moisture and oil contents, crispness, fatty acid profile, volatile compounds, and odour intensity was investigated. Roasting causes changes in appearance, texture and flavour, due to dehydration, browning, lipid oxidation, and diverse structural changes. The moisture content and hardness of the samples significantly decreased with all roasting methods. Roasting resulted in higher amounts of characteristics aroma compounds and only microwave roasting increased the oil content. The final recommendation is that microwave roasting at 480 W for 4 min led to roasted almonds of high physicochemical [dark and intense colour (L*44.9, a*8.4, and b*19.6), the highest content of total volatile compounds (132 mg kg^?1), 85.2 % of unsaturated fatty acids], and sensory (high intensity of “roasted almond” aroma) quality. Microwaves can be used for roasting wild almond as a quick, safe, and economical method.     

Microwave roasting effects on the physico-chemical composition and oxidative stability of sunflower seed oil

The purpose of the present study was to explore the influences of microwave heating on the composition of sunflower seeds and to extend our knowledge concerning the changes in oxidative stability, distribution of FA, and contents of tocopherols of sunflower seed oil. Microwaved sunflower seeds (Helianthus annuus L.) of two varieties, KL-39 and FH-330, were extracted using n-hexane. Roasting decreased the oil content of the seeds significantly (P<0.05). The oilseed residue analysis revealed no changes in the contents of fiber, ash, and protein that were attributable to the roasting. Analysis of the extracted oils demonstrated a significant increase in FFA, p-anisidine, saponification, conjugated diene, conjugated triene, density, and color values for roasting periods of 10 and 15 min. The iodine values of the oils were remarkably decreased. A significant (P<0.05) decrease in the amounts of tocopherol constituents of the microwaved sunflower oils also was found. However, after 15 min of roasting, the amount of α-tocopherol homologs was still over 76 and 81% of the original levels for the KL-39 and FH-330 varieties, respectively. In the same time period, the level of σ-tocopherol fell to zero. Regarding the FA composition of the extracted oils, microwave heating increased oleic acid 16–42% and decreased linoleic acid 17–19%, but palmitic and stearic acid contents were not affected significantly (P<0.05).     

Phytonutrient content and oil quality of selected edible oils upon twelve months storage

Edible oils contain naturally occurring phytonutrients and therefore exhibit numerous beneficial health effects. However, the phytonutrients tend to degrade in different extent with storage duration and temperature. In this study, the impact of storage conditions on the stability of phytonutrients, including vitamin E, carotenoid, phytosterols and squalene, and oil quality, including free fatty acids (FFA), peroxide value (PV), anisidine value (AV), and oxidative stability index (OSI) of red palm-pressed mesocarp olein, palm olein, extra virgin olive oil, and sunflower oil were investigated. The oils were stored in three conditions, 23°C (with light and without light) and 35°C (without light). Results showed that the retention percentages of phytonutrients where in the range of 0%–100% for vitamin E, 51.24%–83.63% for carotenoid, 83.40%–100% for phytosterols and 27.94%–100% for squalene. Pearson correlation analysis between phytonutrients and oil quality of oils in different storage conditions showed that correlation coefficient values (r) were in the range of −1 to 0 for FFA, −1 to 0.22 for PV, −1 to 0.33 for AV, and −0.23 to 1 for OSI, implying that correlations between both variables are not in same direction. Degradation studies of phytonutrients using zero-order kinetic model where optimum-case conditions exhibited highest half-life (t_1/2) among the three conditions. In conclusion, storage conditions and synergistic effect affected the phytonutrients stability in the oils and oil quality in different extent. In general, storage at ambient temperature and dark condition contributed to the best phytonutrients retention and oil quality.     

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.     

Influence of roasting conditions on fatty acids and oxidative changes of Robusta coffee oil

The aim of this study was to determine the influence of roasting conditions, including elevated humidity of air used in the process, on the properties of coffee oil. Beans of Robusta coffee were roasted in a laboratory convective roaster with a possibility of changing the temperature, humidity, and velocity of roasting air. Roasting temperatures from 190 to 216°C, air humidity from 0.07 to 1%, and air velocity of 0.5 and 1 m/s were used. Parameters analyzed in roasted beans were: oil content, fatty acids composition, including trans fatty acids using the GC/FID method and indicators of oxidation level, namely peroxide value and content of conjugated dienes and trienes. Also a thermal profile of oil with the use of the DSC method and finally the bean aroma were evaluated. For maintaining the maximal amount of PUFA, the most favorable roasting conditions were, either, roasting at relatively high temperature and short time, or roasting at low temperatures. Using moderately high temperature resulted in the highest oxidative changes, but on the other hand, the aroma of received beans presented the best sensory properties. For the best nutritional properties, the best roasting conditions were: temperature 210°C and 1% humidity content in roasting air at 1 m/s flow velocity. In such conditions roasted beans obtained a very high quality aroma, and the roasting time was relatively short. Practical applications: This research concerns the quality of oil obtained from roasted coffee beans. The composition of coffee oil changes slightly during roasting, but nevertheless it might be a source of peroxides and trans fatty acids in human diet. In industrial processing coffee oil is extracted from the remains left over from instant coffee production, and it is a popular agent for aromatizing food products. Thus, in this kind of processing, roasting conditions that limit the unfavorable changes of coffee oil should be used.     

Deterioration Kinetics of Crude Palm Oil,Canola Oil and Blend During Repeated Deep-Fat Frying

The oxidation of vegetable oils is generally treated as an apparent first order kinetic reaction. This study investigated the deterioration of crude palm oil (CPO), refined canola oil (RCO) and their blend (CPO:RCO 1:1 w/w) during 20 h of successive deep‐fat frying at 170, 180 and 190 °C. Kinetics of changes in oil quality indices, namely, free fatty acid (FFA), peroxide value (PV), anisidine value (p‐AV), total polar compounds (TPC) and color index (CI) were monitored. The results showed that FFA and PV accumulation followed the kinetic first order model, while p‐AV, TPC and CI followed the kinetic zero order model. The concentration and deterioration rate constants k, increased with increasing temperatures. This effect of temperature was modeled by the Arrhenius equation. The results showed that PV had the least activation energies E_a (kJ/mol) values of 5.4 ± 1 (RCO), 6.6 ± 0.7 (CPO) and 11.4 ± 1 (blend). The highest E_a requirement was exhibited by FFA with a range of 31.7 ± 3–76.5 ± 7 kJ/mol for the three oils. The overall E_a values showed that the stability of the blend was superior and not just intermediate of CPO and RCO. The correlation of the other oil quality indices with TPC indicated a positive linear correlation. The p‐AV displayed the strongest correlation, with mean correlation coefficient r_s of 0.998 ± 0.00, 0.994 ± 0.00 and 0.999 ± 0.00 for CPO, RCO and blend, respectively.     

Use of Phagotrophic Microalga Ochromonas danica to Pretreat Waste Cooking Oil for Biodiesel Production

In this study, the feasibility of pretreatment and/or upgrading of waste cooking oil (WCO) using the microalga Ochromonas danica was investigated. Two WCO samples with initial acid values (AV) of 10.7 mg KOH/g (~5.4 % FFA content) and 3.9 mg KOH/g (~2.0 % FFA content) were examined. The algal cells engulfed oil droplets and grew rapidly on both WCO samples. The cell growth rates on WCO were compared with the rates on olive oil, with or without surfactant addition to make the oil droplets smaller and easier for algal ingestion. Comparison was also made with the growth rate in a sugar‐based medium. More importantly, contacting the WCO with the phagotrophic O. danica cells was found to decrease the acid values of the remaining oil by 2.8 and 2.4 mg KOH/g WCO, respectively. The O. danica‐pretreated WCO, with lower acid values, are potentially better feedstock for biodiesel production.     

Aqueous Enzymatic Extraction of Oil and Protein Hydrolysates from Roasted Peanut Seeds

To evaluate the effects of the roasting process on the extraction yield and oil quality, peanut seeds were roasted at different temperatures (130–220 °C) for 20 min prior to the aqueous extraction of both oil and protein hydrolysates with Alcalase 2.4 L. Roasting temperatures did not significantly affect the yields of free oil, whereas the temperature of 220 °C led to a reduced recovery of protein hydrolysates. The color and acid values of peanut oils did not change significantly with roasting temperatures. The enzyme-extracted oil with roasting at 190 °C had a relatively low peroxide value, a strong oxidative stability, and the best flavor score. Using the same seed-roasting temperature (190 °C), quality attributes such as color, acid and peroxide values, phosphorus content and oxidative stability of the enzyme-extracted oil were better than those of the oil obtained by an expeller. After the peanut seeds were roasted at 190 °C for 20 min, with a seeds-to-water ratio of 1:5, an enzyme concentration of 2%, and an incubation time of 3 h, the yields of free oil and protein hydrolysates were 78.6 and 80.1%, respectively. After demulsification of the residual emulsion by a freezing and thawing method, the total free oil yield increased to 86–90%.     

Regeneration of Used Frying Oil

Used frying oils were purified in a packed column using different amounts of silica gel (SG), aluminum oxide (AO), activated charcoal (AC), bentonite (B), magnesol XL (M), calcium carbonate (CC), zeolite (Z), bleaching earth (BE) and/or their binary, triple, and quaternary combinations. SG (15 g) improved total polar material (TPM) by 100 %, conjugated diene (CD) content by 84 %, and p-anisidine value (AV) by 104 %, while AO and M improved free fatty acid (FFA) contents by 103 and 105 %, respectively. On the other hand, AC and M bleached the color by 100 and 90 %, respectively. As the amount of adsorbent in the column increased, FFA, CD, AV, and color improved. When the amount of used sunflower oil (UO1) loaded in the column containing SL was increased, FFA, CD, AV and color values increased, while no change was observed in TPM up to 60 g of UO1. Loading UO1 at 150 °C in the column caused the absorbance values at 460 nm to decrease from 0.740 to 0.240, while the amount of adsorbed tocopherol increased compared to UO1 at 25 °C. The increasing number of adsorbents within the column further improved the physicochemical properties of UO1 when it was used 30 g. However, as the amount of different type of used oils (UO2, UO3 and UO4) was increased to 300 g, improvement ratios of all parameters decreased.     

Chemical and sensory properties of gas-purged,minimum-refined,extruded-expelled soybean oil

Developing low-cost oil refining methods is critical to business that use low-cost extrusion-expelling (E-E) to crush soybeans so they can capture the full value-added potential by marketing finished oils. Normal commodity (CO) and high-oleic (HO) E-E soybean oils were minimum-refined, gas-purged, and evaluated in frying applications. Degummed commodity oil (DCO) and minimum-refined (degummed and deacidified by Magnesol® adsorption) CO and HO oils were gas-purged with N₂ for 1 h at 150°C. For DCO, gas purging did not affect PV, oxidative stability index (OSI), FFA, color, and total tocopherol content, but p-anisidine value (AV) increased. For CO, the minimum-refined, gas-purged oil did not differ from degummed, gas-purged oil in terms of p-AV, OSI, tocopherol content, and color. PV and FFA were lower in minimum-refined, gas-purged oil. Minimum-refined, gas-purged HO had much higher OSI, tocopherol, and FFA levels than did minimum-refined, gas-purged CO. The oils were used to fry bread cubes at 185°C. Fried bread cubes were stored under various conditions and evaluated for flavor attributes. These oils were different in toasty/nutty, beany/grassy, and oxidized flavors, as well as overall flavor intensity and desirability. Minimum-refined, gas-purged oils produced fried bread cubes having initial flavor profiles similar to those fried in commercial oil; however, when fresh oils were used they were less stable to oxidation. Longer heating times of the minimum-refined, gas-purged oils produced bread cubes with better oxidative stabilities than those produced with commercial oil.     

Characterisation of acorn oils extracted by hexane and by supercritical carbon dioxide

Acorn fruit oils from two species of oak, Quercus rotundifolia L. (holm‐oak) and Quercus suber L. (cork‐oak), were extracted by n‐hexane. The acorn fruit of Quercus rotundifolia L. was also extracted by supercritical CO₂ at 18 MPa and 313 K, a superficial velocity of 2.5 × 10^?4 ms^?1, and a particle size diameter of 2.7 × 10^?4 m. The oils were characterised in terms of fatty acids, triglycerides, sterols, tocopherols, and phospholipids. The main fatty acid in both fruit species was oleic acid (about 65%), followed by linoleic acid (about 16.5–17%) and palmitic acid (about 12.1–13.4%). The main triglyceride found in acorn oils was the OOO (oleic, oleic, oleic) triglyceride (33–38%), followed by the POO (palmitic, oleic, oleic) triglyceride (12.6–18.2%). In terms of sterols, the main component in acorn oils of both species was β‐sitosterol (83.5–89%), followed by stigmasterol (about 3%). However, in Quercus suber L., acorn oil was found to consist to 10.2% of campesterol. The amount of cholesterol was low (0.27% for the Quercus rotundifolia L. oil extracted by supercritical fluid extraction, and 0.18% for the oil extracted by n‐hexane). The Quercus suber L. acorn oil presented 0.1% of cholesterol. The total amount of tocopherols in Quercus rotundifolia L. acorn oils was almost the same when the oil was extracted by n‐hexane (973 mg/kg oil) or by supercritical CO₂ (1006 mg/kg oil). The Quercus suber L. acorn oil presented a high value of total tocopherols (1486 mg/kg oil). The supercritical CO₂ did not extract the phospholipids. The amount of phospholipids was very similar for both species of oak acorn oils extracted by n‐hexane. Oxidative stability was also studied, by using the peroxide value and the Rancimat method, revealing that all the oils were significantly protected against oxidation. The influence of storage, under several conditions, on the oxidative stability was also studied. The Quercus rotundifolia L. oil extracted by n‐hexane was better protected against oxidation after a few days of storage at 60 °C.     

A novel method for the determination of acid value of vegetable oils

The voltammetric behavior of naphthoquinone in the presence of free fatty acids (FFA) at the polypyrrole (PPy)‐modified electrode was investigated in an ethanol/1,2‐dichloroethane (3 : 1) solution containing 0.1 M LiClO₄. A well‐defined new reduction peak appeared at a more positive potential and was higher than that obtained at the bare Pt electrode. Based on the fact that the new reduction peak current showed a good correlation with the concentration of fatty acids, an electroanalytical method for the acid value (AV) of vegetable oils was developed using the PPy‐modified electrode in linear potential sweep voltammetry. The experimental parameters were optimized to obtain a sensitive voltammetric response in this work. A linear calibration graph was obtained in the concentration range of 5.0×10^–6–6×10^–3 M for FFA (R = 0.993), with a sensitivity of 2.41×10^–2 A L/mol and a detection limit of 1.2×10^–6 M (S/N = 3). Each assay of vegetable oil sample took about 80 s. The developed method is applied to the AV determination of six commercial vegetable oils. The results well agreed with those obtained by the titration method. Compared to the conventional titration method, the proposed method is superior in sensitivity and accuracy and requires a small amount of vegetable oil sample, with no pretreatment.     

Chemical and fungal evaluation of graded sunflowerseed

Thirty-four samples of commercial oil-type sunflower-seed graded No. 1, 10 samples graded No. 2 and 33 samples graded Sample grade (SG) were used to study the relationship between percent heat damage, an important grading character, and percent FFA, percent color and UV absorption of extracted oil, percent germination and number and identities of fungi present. Seventy-two fungal species belonging to 28 genera were isolated. Thirty-seven fungal species in 17 genera were isolated from grade No. 1 seed; 68 species in 13 genera were isolated from grade No. 2 seed, and 68 species in 26 genera were isolated from SG seed. The genera most frequently isolated from grade No. 1 seed wereAlternaria (85.3%),Phoma (4.7%) andCladosporium (4.5%).Alternaria alternata was recovered from all No. 1 samples and comprised 75.6% of all isolates. The genera most frequently isolated from grade No. 2 seed wereAlternaria (74.5%),Eurotium (8.4%) andPhoma (7.7%). Fewer fungal species were isolated from grade No. 2 than from No. 1 seed, but a greater recovery of storage fungi was found for No. 2 seed (13.3%) than for No. 1 seed (2.5%).Alternaria (33.8%),Eurotium (33.1%) andMicroascus (8.3%) were the genera most frequently isolated from SG seed. Species of common storage fungi (Eurotium, Microascus, Penicillium andAspergillus) were recovered more frequently from SG than from Grades No. 1 and No. 2. In general, as the quality of the seed decreased from grade No. 1 to grade No. 2 to SG, there was an increase in percent heat damage, percent FFA, Lovibond color and UV absorption of extracted oil, and a decrease in percent germination. Analysis of variance of the quality characteristics data showed no significant differences between grade No. 1 and No. 2 seed except for UV 228 nm absorption. However, the quality characteristics of SG seed all differed significantly from those of grades No. 1 and No. 2 seed with the exception of percent seed yielding fungi. Correlation coefficients of the quality characteristics of SG showed a slight relationship between heat damage and percent FFA (r=0.63) and UV 228 nm absorbance (r=0.68). Although many of the SG seed were badly heat damaged, no statistical relationship was found between percent heat damage and percent seed yielding fungi or total isolates of storage fungi. The data in this study show that errors exist in grading decisions when seed are judged visually to be heat damaged.     

Effects of Seed Coat on Oxidative Stability and Antioxidant Activity of Apricot (Prunus armeniaca L.) Kernel Oil at Different Roasting Temperatures

Apricot kernels were roasted at various temperatures (120–180 °C) for 10 min and changes in the fatty‐acid profiles, oxidative stability, and antioxidant activity, as well as the total phenolic contents (TPC) of the oils and skin (seed coat), were monitored. Roasting has no obvious influence on profiles and contents of fatty acid, induction period (IP), browning index, TPC, and antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid), (ABTS) and Oxygen Radical Absorbance Capacity (ORAC) of oils obtained from apricot naked‐kernel, but increases IP, TPC, and oxidative stability in oils obtained from apricot kernel with skin. All results in the present work demonstrated that thermal treatment accelerated the production and transference of alcohol‐soluble phenolics into the oil, and improved the oil oxidative stability. It is not Maillard reaction products but alcohol‐soluble phenolic compounds in skins that play a role in improving the oxidative stability and antioxidant activity of oils, and inhibition for primary peroxide production was more effective than secondary peroxide production at a low roasting temperature and a short roasting time. The present findings can advance knowledge on the conditions used for utilization of coproducts (skin) of apricot kernel and facilitate large‐scale production of stable oil against oxidation.     

Babassu Oil (Orbynia phalerata), an Artisanal Product: Process Optimization of Seed Roasting on Yield,Phenolic Compounds,and Antioxidant Capacity

Babassu oil has high concentrations of phenolic compounds. When seeds are preheated, these compounds tend to migrate to the oil depending on the degree of roasting applied. This study aims to optimize the roasting conditions of babassu seeds using response surface methodology (RSM) and the desirability functions. A central composite rotational design (CCRD) is employed to investigate the effects of two independent variables, temperature (X₁) and roasting time (X₂) which significantly affected response variables, namely yield (%), total phenolics content (TPC), number of phenolic compounds, oxygen radical absorbance capacity, acid value and peroxide value. The quadratic model is adjusted for most responses. The roasting temperature of 222 °C and the roasting time of 43 min are standardized as ideal conditions. Thus, the oil produced at the optimized conditions shows a yield of 54.47% and TPC of 91.53 mg GAE/100 g. In the control oil sample, the presence of phenolic compounds analyzed by HPLC-DAD is not observed while under optimized conditions, seven phenolic compounds are observed. The model of optimized conditions shows a good correlation between the predicted and experimental values. In general, these results demonstrate the effectiveness of optimum roasting conditions in improving the quality of bioactive compounds in babassu oil. Practical Applications : This work aims to optimize the babassu seeds roasting process to obtain oil with a greater number of phenolic compounds and better antioxidant capacity. As the first study on babassu seeds roasting, it contributes to the generation of important data in relation to the identification and quantification of phenolic compounds in the oil. Finally, the optimum roasting conditions established in this work can be explored commercially in babassu oil extraction.     

Physiochemical Properties of <Emphasis Type="Italic">Jatropha curcas</Emphasis> Seed Oil from Different Origins and Candidate Plus Plants (CPPs)

The physicochemical properties of Jatropha seed oil from 9 geographical origins and 24 candidate plus plants (CPPs) were evaluated. The yield of seed oil obtained by Soxhlet extraction using n-hexane as solvent varied from 40.0% (Malaysia) to 48.4% (Vietnam) among seeds from different origins and 32.1% (CPP-17) to 48.8% (CPP-01) (w/w) among CPPs. Density, specific gravity, and refractive index of oil showed very little differences among all the seed sources. Oil from Borneo had the highest free fatty acid (FFA) content (2.3%) and a South African sample had the lowest FFA (0.4%), as oleic acids. Seed oil of CPP-13 had the highest FFA content (1.2%) and seed oil of CPP-17 the lowest (0.3%). Most of the CPPs in this study had an FFA content of less than 1%. Jatropha seed oil of Philippine origin had the highest iodine value (187.3 mg/g oil) and seed oil from Borneo the lowest (83.5 mg/g oil). The lowest saponification values were obtained from seed oil of Philippine origin (189.5 mg KOH/g) and CPP-22 (183.3 mg KOH/g oil) from Malaysia. The maximum higher heating value (40.3 MJ/kg) was obtained from seed oil from Borneo. The cetane numbers range from 25.4 (Indonesia) to 56.0 (Borneo) among the oils of base material and 46.4 (CPP-15) to 53.7 (CPP-06) among CPPs. This study gives basic information of relevance for biodiesel production using Jatropha seeds from various origins.     

The Impact of Fat Deterioration on Formation of Acrylamide in Fried Foods

The current study investigates to what extent the reaction products of thermal degradation directly influence acrylamide formation in French fries. The frying tests at 170 and 180 °C are carried out with rapeseed oil for 32 h with 128 frying cycles. Acrylamide content in French fries is determined by LC-MS/MS. Oxidative and thermal degradation is followed by measuring total polar compounds (TPC), di- and polymerized triacylglycerols (DPTG), monomer oxidized triacylglycerols (MONOX), p-anisidine value (AnV), mono and di-acyl-glycerols (MAG and DAG), acid value (AV), epoxy fatty acids, iodine value (IV), saponification value, and fatty acid composition. During frying, the nature and degradation level of the frying medium have a direct impact on acrylamide formation. It can be shown that the pH-dependent reaction is strongly inhibited at acid values above 0.5 mg KOH g⁻¹ oil. Acidity measured as AV or FFA is mainly caused by oxidation, and less so by hydrolysis of triacylglycerols (TAG) as assumed up to now. Obviously, acid functional groups formed by oxidation of unsaturated fatty acids bound in TAG can act not only as catalyst for dimerization of TAG but also interact with asparagine as most important precursor for acrylamide formation so that no reaction with carbonyl groups for the formation of acrylamide is necessary. Practical applications: The same acidic functional groups that are known to catalyze the formation of dimeric TAG under frying conditions (160–190 °C, access of oxygen) in a nonradical mechanism apparently can also deactivate asparagine by protonization as a potential precursor for the formation of acrylamide. It is recommended not to reduce acidity of used frying oil by active filter aids below AV ≥ 0.5 as it helps to reduce acrylamide contamination of fried food.     

Deodorization optimization of Camelina sativa oil: Oxidative and sensory studies

Camelina sativa oil (CO) is characterized by a high content (up to 40 wt %) of essential α‐linolenic acid and characteristic odour and flavour. Deodorization of highly unsaturated oils requires great attention as the refining process involves thermal treatment which affects oil integrity. In the present study RSM and principal component analysis (PCA) were used to optimize bench‐scale deodorization of CO. Mathematical models were generated through multiple regressions with backward elimination, describing the effects of process parameters (temperature, steam flow, time) on oil quality indicators [peroxide value (PV), p‐anisidine value (p‐AV), γ‐tocopherol (γ‐T) and oxidative stability (OS)]. Additionally, sensory evaluation was performed. RSM analysis showed a significant effect of deodorization temperature and to a lesser extent, deodorization steam flow and time on removal of oxidative compounds, flavour and odour. PCA of chemical and sensory results showed that deodorization temperature affected the sensory properties in the samples. The best conditions for removing undesirable flavour and odour were achieved by using a deodorization temperature of 195–210°C.