Free Fatty Acid Values Research Articles

Efficacy of vitamin E with or without probiotic, astaxanthin or rosemary extract on microbiological and chemical characteristics of fresh and frozen fillet of rainbow trout (Oncorhynchus mykiss)

Microbiological properties, proximate composition, total volatile base nitrogen (TVB-N), pH, fatty acid (FA) composition, peroxide value (PV), free fatty acids (FFA), histamine and water holding capacity (WHC) in fresh and frozen-stored (3, 6, and 12 months at −18 °C) fillets of rainbow trout (Oncorhynchus mykiss) (170.46 ± 1.16 g) fed diets containing 50 mg vitamin E (control) alone or with 200 mg vitamin E (VE), 500 mg probiotic (PR), 50 mg astaxanthin (AS) and 500 mg rosemary extract (RE) kg−1 for 4 months were assessed. Decreasing trends in fillet WHC (specially in control and AS groups) were observed in the 12-month storage. Although a low increase in fillet bacterial population occurred during the storage time in all groups, lower bacterial counts were observed in PR group. Fillet histamine, TVN and pH levels were in the accepted ranges in all treatments during the storage. Also, FFA level and proximate composition of fillets didn’t show any significant change during the storage time. The PR diet controlled microbiological activity and variations of pH and PV of fillet samples better than the other experimental diets. It also prepared an appropriate FA composition and retained the desired amounts of both n-3 and n-6 polyunsaturated fatty acids (PUFAs) in fish fillets until the end of storage period, while no significant differences were seen in values of TVN, pH, FFA and histamine among the treatments. However, AS and RE diets tended to be less functional maintaining the fillet quality during the storage time than the other experimental diets. According to the results, a diet containing 500 mg bacilli probiotic with 50 mg vitamin E kg−1 could be highly efficient in maintaining a good quality of trout fillet stored at − 18°C for 12 months.

Optimization and characterization of acid catalyzed castor biodiesel and its blends

In terms of energy security, biodiesel has become an alternative, safe, and biodegradable fuel. Here, to produce biodiesel from castor oil, a transesterification process was carried out using an acid-catalyzed catalyst. Three blends (B10, B20 and B30) were prepared by using different proportions of castor biodiesel and petro-diesel. Biodiesel optimum yield of 80% was obtained from 5 mL of castor oil with the influence of different parameters such as 1.75 mL of methanol and 0.08 mL of conc. H2SO4, at 65 ℃, for 3 hours with 600 revolutions per minute stirring speed for 5 mL of castor oil. Physiochemical properties of all samples such as moisture contents, iodine value, free fatty acid value, saponification value, ester value, acid value, peroxide value, viscosity (at 40 ℃), specific gravity, refractive index, density, boiling point, average molecular weight, and higher heating value were determined. Castor biodiesel characterization was resulted as 0.112 (percentage), 86 mg KOH/g, 1.0878 mg KOH/g, 0.439 mg KOH/g, 84.9122 mg KOH/g, 86.32 gI2/100 g, 20.66 Meq/100 g, 0.8850 g, 17.21 cSt, 1.4667 nD, 0.8910 g, 290 ℃, 1982.05 g, and 44.479 MJ/Kg min, respectively. The functional groups were investigated by using FTIR. In the present study, it was demonstrated that biodiesel can be produced using a method of acid-catalyzed transesterification by using castor oil.

Formulation with sage tea-loaded fish oil-based microcapsules to delay oxidation.

Fish (Engraulis encrasicolus) oil was successfully microencapsulated using sage essential oils prepared in three different concentrations as 1% (S1), 2% (S2) and 3% (S3). The microencapsulated fish oil powders fabricated with spray drying were stored at room temperature (24 ± 1°C) in order to determine the oxidative deterioration for 12weeks. The highest microencapsulation efficiency was observed in the S3 (60.17%) as compared with other groups. Although the changes in free fatty acid (FFA) values were defined between 6.04 and 9.29% at the end of the storage period, the lowest FFA value was found in S2 samples (p < 0.05). Among the microencapsulated samples, the highest peroxide value (PV) was measured as 20.24meq O2/kg for S1 at the 11th week of the experimental period. Moreover, statistical differences between the control (25.93meq O2/kg) and S1 samples were observed (p < 0.05). The rapid increase in the thiobarbituric acid (TBA) value of fish powders was delayed by microencapsulation technique fabricated with spray drying. The use of sage essential oils within this combination effectively retarded the oxidation in fish oil powders at ambient storage, indicating cost-effective for the food industry. Therefore, encapsulation of fish oils with sage oil using the spray drying technique has improved oxidation stability of fish oil and can be used for food applications.

Recycling of used vegetable oils by powder adsorption.

The treatment of used vegetable oil (UVO) with seven different adsorbents and through two different procedures (stirring and gravity filtration) was explored. Important differences in terms of density, turbidity, electrical resistance, free fatty acids (FFAs) content and relative fatty acid distribution were observed. Different outcomes were shown depending both on the adsorbent and on the procedure. Lower values of density and FFAs were registered for oils treated by gravity filtration with portland (respectively 0.6% and 0.81 g/ml) and celite (respectively 0.7% and 0.72 g/ml). Considering the undesired leaching from the powder to the oil, related to the turbidity, the celite resulted more suitable for the oil recycling (241 Nephelometric Turbidity Unit (NTU) for portland vs 184 NTU for celite). In addition, Fourier-transform infrared spectroscopy combined with multivariate analysis allowed to determine a chemical fingerprint relative characteristic of vegetable oils recycled by gravity or by adsorption by stirring.

Safety and quality assessment of street-vended barbecue chicken samples from Faisalabad, Pakistan.

The current study was designed to assess the safety and quality status of street-vended barbecue chicken samples. The samples were collected from four regions of Faisalabad city: Ghulam Mohammad Abad (R1), Jhang Road (R2), Sargodha Road (R3), and Satiana Road (R4); and compared with the self-prepared barbecue chicken sample (R0). Purposely, all the collected samples were subjected to assess the quality aspects by physicochemical analyses. The results of the physicochemical analysis showed that moisture content varied from 54% to 60%, crude protein 26.97% to 32.87%, crude fat 7.25% to 9.00%, crude ash 1.61% to 1.72%, pH 5.60 to 6.30, free fatty acid value 1.00% to 1.39%, and peroxide value 0.63 to 0.84 meq/Kg. Results pertaining to the enumeration of total microbial load and total coliform count exhibit 2.39-5.17 and 1.20-3.20 log cfu/g, respectively. The samples were assessed for heavy metals (Pb, Zn, Cd, and Fe) by atomic absorption spectrophotometer (AAS). The concentration of highly toxic metals Pb and Cd was found to be much higher than recommended value as they ranged from 1.90 to 3.70 mg/kg for Pb and 0.10 to 0.90 mg/kg for Cd. However, the level of essential metals (Fe and Zn) in barbecue chicken samples ranged from 67.10 to 180 and 8.30 to 35.80 mg/kg which was much higher than their safe limits for Fe (15 ppm) and Zn (5ppm), respectively. The study concludes that the consumption of street-vended barbecue chicken possesses to be a serious public health risk for consumers.

EXTRACTION, CHARACTERIZATION AND FTIR ANALYSIS OF OIL EXTRACTED FROM COTTON SEED (GOSSYPIUMHIRSUTUM)

In this study cottonseed oil extracted from Gossypiumhirsutum (Cotton seed) was carried out. The extraction was done using soxhlet method with n-hexane as the solvent. The extracted oil was characterized by different parameters. This includes the acid value, the free fatty acid value, the saponification value, the boiling point, the density, the pH value as well as the FT-IR spectra. The acid value, free fatty acid value, saponification value, and boiling point were found to be 3.903 mg KOH/g, 1.914 mg KOH/g, 193.23 mg KOH/g and 2340C respectively. The density of the oil was found to be 0.928 gcm-3 , while the pH value was 5.6. FT-IR analysis was carried out to ensure the quality of the extracted oil. The functional groups detected were sp2 CH stretches, sp3 C-H stretches, a strong band of –C=O of an ester and medium band of –C-O of an ester, this confirmed that the oil was not rancid and my resist rancidity due to the presence of tocopherol. The oil was found to be edible and of numerous potentials domestically and industrially after comparisons were made with values obtained from literature.

Quality assessment and degradative changes of deep-fried oils in street fried food chain of Kashmir, India

Repetitive use of same oil for deep-frying over a prolonged time period is a common practice followed by street vendors across various developing countries. This practice usually results in generation of harmful compounds imposing serious health threats to consumers. Frying oil samples (fresh, in-use and discarded) and commonly consumed fried street foods of Kashmir were randomly collected from 16 street food vendors of srinagar town and its adjacent areas for the assessment of their quality changes during repetitive deep frying. Significant increase in total SFA (saturated fatty acids), total MUFA (monounsaturated fatty acids) and total TFA (transfatty acids) content and decrease in total PUFA (polyunsaturated fatty acids) was observed in in-use, discarded oil and street foods as compared to fresh oil, reflecting the higher degree of oxidative degradation on repetitive use of same oil. The extent of oxidative degradation was highly influenced by the type of food fried, with lipid-based products showing higher degradation. High free fatty acid value (FFA˃1%), peroxide value (PV˃10meq/kg), P-anisidine value (P-Av˃6), color (higher ΔE), and TOTOX (Totox value˃19.5 mEq/kg) value revealed that only 20% of the in-use frying oil and 10% food products were safe for consumption. However, TPC test, a widely used measure of oxidative degradation suggested that majority of the in-use frying oil were of acceptable quality, thus greatly underestimating oil degradation.

Meat yield and meat quality characteristics of indigenous, Hilly♂×Sonali♀ crossbred and commercial broiler chicken of similar weight at different storage time

The experiment was conducted to investigate meat yield and quality characteristics of indigenous, crossbred Hilly♂ × Sonali♀ and commercial broiler chickens at similar live weight. For this purpose male and female indigenous chickens were purchased from local market, while Hilly♂ × Sonali♀ crossbred was reared up to 12 weeks at Bangladesh Agricultural University (BAU) poultry farm. Sexed male and female of Ross 308 broiler chicks were also reared BAU poultry farm up to 30 days. Six male and six female chickens from each of indigenous, Hilly♂  Sonali♀ and commercial broiler were slaughtered, eviscerated and dissected to compare meat yield and meat quality characteristics during 0, 15 and 30 days of storage period at 1000 g (±50 g) body weight. The eviscerated and defeathered carcasses were stored at -18°C for 0, 15 and 30 days .Considering Indigenous, Hilly♂ ×Sonali ♀ and Broiler chickens of both sexes, shank, neck, carcass yield, dressed weight, breast meat weight were significantly (p&lt;0.05) higher in commercial broiler while wing meat and thigh meat were higher in Hilly♂ × Sonali♀ chicken. The dry matter, crude protein were significantly higher in indigenous chicken while cooking loss, ether extract, ash, peroxide value, free fatty acid value and thiobarbituric acid value were found significantly higher in commercial broiler during different storage time in both sexes. The meat yield parameters did not differ significantly among three storage time. However, cooking loss, pH and crude protein decreased, while dry matter, ether extract, ash, peroxide vale, free fatty acid value, thiobarbituric acid value, increased with the increasing of storage time.

Utilizing the Bioactivity of Nutmeg Leaf Oil to Raise the Natural Antioxidant Content of Cooking Oil

Nutmeg oil, also known as essential oil, is an oil extracted from the seeds or leaves of nutmeg through a distillation process. Nutmeg oil has several advantages, including as an antibacterial ingredient, an additive in the perfume industry, and as a raw material for medicines in the pharmaceutical industry. In this study, the essential oil from nutmeg leaves was produced using the steam-water distillation method, where the nutmeg leaves were dried before the steam-water distillation process was carried out. As a fixed variable, 150 g of bulk cooking oil and 150 g of bimoli cooking oil were used, while as a variable, steam-water distillation temperature was used with temperature variations of 105 oC, 115 oC, and 125 oC. Samples of 1 mL, 2 mL, 3 mL, and 4 mL of nutmeg leaf oil were mixed with bulk cooking oil to compare the free fatty acid oxidation ability and peroxide value after 1 day, 3 days, 5 days, and 7 days. Analysis of the compound content of nutmeg leaf oil, free fatty acids, peroxide number, and antioxidant activity was carried out using GC-MS and 0.004% DPPH. The production of nutmeg leaf oil was obtained as much as 91 ml by steam distillation at a maximum temperature of 125 oC. Using a DPPH of 0.004 percent and a quantitative measure of IC50, the optimal antioxidant activity at 125 oC was found to be 2.03 percent. A comparison of free fatty acid numbers and peroxide values found in this study revealed that pure bimoli cooking oil had the lowest free fatty acid and peroxide values.

Physicochemical Properties and Fatty Acid Composition of Tamarindus Indica Seeds Oil

A research work was carried out on the physicochemical properties and fatty acid composition of Tamarindus indica seeds oil using standard Analytical methods and PYE Unican 304 Gas Chromatography. The physicochemical properties results for seed oil were: acid value (5.10), peroxide value (9.60), free fatty acid (2.05), iodine value (82.50), saponification value (279.20), refractive index (1.467) and specific gravity (0.8423).The results indicated that the oils of Tamarindus indica seed might be useful for domestic consumption due to low acid value, free fatty acid and peroxide value. The fatty acids compositions showed that seed oil contained higher unsaturated fatty acids (74.0%) and low saturated fatty acid (26.0%) with most abundant acid being linoleic acid methyl ester (44.967%), thus making it more nutritionally important.

Valorisation of Basa fish (Pangasius bocourti) waste: Oil extraction and encapsulation

SummaryFish waste is a source of various nutraceuticals and bioactive compounds such as polyunsaturated fatty acids (PUFAs), peptides, vitamins and minerals. This waste can be utilised for the extraction of fish oil for the preparation of value‐added supplements for humans. In this study, oil was extracted from wastes (bones, head and viscera) of Basa (Pangasius bocourti) fish and encapsulated with alginate as a coating material using the simple extrusion process. In total fatty acid composition, the most predominant was monounsaturated fatty acid (MUFA) (30.74–61.67%), followed by saturated fatty acid (SFA) (26.45–38.22%) and PUFA (7.03–21.01%) in different sections. Alginate concentration (2.5%) with oil loading of 30% showed higher emulsion stability with the least pore space, hence, considered optimum for encapsulation of oil. The encapsulated beads were stable up to 12 days as determined by peroxide value (18.67 ± 1.15 meq Kg−1), acid value (14.13 ± 0.35 mg KOH g−1) and free fatty acid value (8.42 ± 0.51%) when stored at room temperature.

Rheological and Physicochemical Analysis of Nonedible Oils Used for Biodiesel Production.

Rheological and physicochemical characteristics of edible oils used for biodiesel production are well established; nonetheless, the rheological and physicochemical characteristics of nonedible oils are yet to be established. The present study therefore focuses on rheological and physicochemical characterization of nonedible vegetable oils that can be used as biodiesel feedstock. The selected vegetable oils studied include cashew nut shell liquid (CNSL), castor oil (CO), Croton megalocarpus oil (CMO), Podocarpus usambarensis oil (PUO), and Thevetia peruviana oil (TPO). Physicochemical parameters analyzed were free fatty acids, acid value, saponification value, peroxide value, iodine value, specific gravity, and moisture content using methods by the Association of Official Analytical Chemists (AOAC). Rheological properties were analyzed using a VT-550 Thermo Haake Viscotester operated by the Rheowin 3 Job Manager software. The preset parameters in the Viscotester were shear rate and temperature. The shear rate increased uniformly from 5 to 100 s–1 at the temperature range of 30–60 °C. The experimental data were fitted into rheological models of Newton, Bingham, Ostwald–de Waele (power-law), and Herschel–Bulkley using Rheowin 3 Data Manager. The oil yield was 29–65%, highlighting the feedstock’s potential for commercial biodiesel production. At a constant temperature, all oil samples exhibited a Newtonian flow behavior. In contrast to edible oils, nonedible oils exhibited high shear stress, emphasizing the reconstruction of new appropriate designs of production systems. The rheological models appropriate to represent the flow behavior of the samples were the Newton and Ostwald–de Waele models, with a fit of R2 = 0.990–1.000.

Solvent extraction of oil from three cultivars of Nigerian mango seed kernel: Process modeling, GA - optimization, nonlinear kinetics and comparative characterization

This work investigated the physicochemical and instrumental characterization of oil optimally extracted from three species of mango kernels (Alphonso, Glenn and Fazli) by highlighting their isolated qualities. The effect of temperature (40-58 °C), dosage (0.0033-0.0267 g/mL) and time (0-360 min) was varied at the course of experiment. It was observed that while temperature increment had a corresponding positive impact on mango kernel oil extraction efficiency, the influence of dosage produced a quadratic effect, reaching maximum efficiency at 0.017 g/mL, beyond which an undesirable decline was recorded. Analysis of variance (ANOVA) of process factors gave an F-value of > 80.5 for temperature, indicating that temperature was the most important parameter that influenced the extraction process, while kernel dosage having F-value < 20 was the least influential process parameter. Process optimization by response surface methodology coupled genetic algorithm (RSM-GA) gave an optimum validation yield of 13.62%, 14.7% and 16.1% for Fazli, Glenn and Alphonso, respectively, at temperature of 56.61 °C, dosage of 0.021 g/mL and extraction time of 275 min. Error function indices obtained from comparative kinetic modeling illustrated that the extraction process was best described by pseudo second order model (R2 > 0.96, Adj-R2 > 0.95). Also, Elovich kinetics highlighted the dominance of rate diffusion over washing mechanism in the extraction process. Physicochemical characterization showed that while all the mango kernel oil (MKO) species exhibited stability against oxidative rancidity, Alphonso species having an acid value of 2.74 mg KOH/g and 1.37% free fatty acid value, highlighted its superior physicochemical qualities over Fazli and Glenn mango kernel oil. GC-MS analysis portrayed the dominance of stearic and palmitic saturated fatty acids in all the three species while myristic acid was only detected in Alphonso mango kernel oil (MKO), emphasizing its application in food and cosmetics industries. X-ray florescence (XRF) demonstrated the significant presence of molybdenum (Mo) element in Glenn mango kernel oil, revealing its unique suitability for application in synthesis of special purpose industrial lubricants. For Alphonso mango kernel oil, XRF revealed that while this oil species has potential application in the production of lubricants with high detergent properties, caution must be taken in the utilization due to the presence of sulphur element in the sample.

Oxidation kinetics and ANN model for shelf life estimation of pearl millet (Pennisetum glaucum L.) grains during storage

AbstractThis work analyzed the impact of storage period and temperature (5, 25, and 45°C) on the rancidity indicators and oxidation kinetics of pearl millet grains stored for 120 days. The storage period and temperature had a significant (p ≤ 0.05) effect on the free fatty acid (FFA), acid value (AV), and peroxide value (PV). An Arrhenius‐type equation was used to estimate the shelf life of grains derived from the oxidation kinetics data of the rancidity parameters. A pseudo‐zero‐order reaction model fit the kinetics of pearl millet grains better than the first‐order reaction model, and this model was also exploited to anticipate the shelf life of the grains during storage. Higher storage temperatures have a less shelf life as compared to the grains stored at a lower temperature. Similarly, the pearl millet grains stored at 45°C have a shelf life of 8.5 weeks, which was much lower than the shelf life of 15.7 weeks at 5°C, respectively. FFA, AV, and PV of pearl millet grains were estimated using artificial neural network modeling based on Levenberg–Marquardt's backpropagation algorithm. Low root mean square error (0.262) values and high R2 (0.998) values indicate a good fit for the developed model. The developed shelf‐life prediction model has a positive significance for the assessment of quality deterioration of grains during storage.Novelty Impact StatementStorage temperature and time impacted the rancidity indicators, such as FFA, PV, and AV in pearl millet grain. These rancidity indicators can be modeled using oxidation kinetics and on Arrehenius equation and ANN modeling shelf life of the grains can be predicted.

Retardation of oxidative rancidity in ghee adding orange peel powder at different storage temperature.

This study is aimed to determine and compare the antioxidant activity of Orange Peel Powder (OPP) in ghee at different temperatures (4°C, 25°C and 60°C) for divergent storage periods (0, 7, 14 and 21days). To compare the antioxidant potentiality, synthetic antioxidant BHA (Butylated Hydroxy Anisole) is used. Twelve ghee samples were prepared where one was control, another one was BHA treated and the rest ten were admixing OPP in ghee at different ratios. After sensory evaluation three highest scored ghee samples (0.5%. 1.0% and 1.5%) were selected. Samples were analyzed for peroxide (PV), thiobarbituric acid (TBA), free fatty acids (FFA) value and radical scavenging activity. Though storage temperature and storage period were increased OPP treated ghee samples peroxide, TBA and FFA values were lowered significantly compared to control samples. Moreover, 1.0% and 1.5% OPP treated ghee samples such values were lowered than BHA treated ghee samples and all these are on the favor of ghee quality. OPP treated ghee samples' DPPH quench potentiality is also stronger than BHA treated ghee samples. Therefore, OPP is a great source of antioxidants and this can be used in ghee as a natural source of antioxidants.

Molecular Hydrogen Improves Rice Storage Quality via Alleviating Lipid Deterioration and Maintaining Nutritional Values.

Improvement of the storage quality of rice is a critical challenge for the scientific community. This study assesses the effects of the irrigation with hydrogen nanobubble water (HNW) on the storage quality of rice (Oryza sativa ‘Huruan1212’). Compared with ditch water control, after one year of storage at 25 °C and 70% RH, the HNW-irrigated rice had higher contents of essential amino acids, especially lysine. Importantly, the generation of off-flavors in the stored rice was significantly decreased, which was confirmed by the lower levels of volatile substances, including pentanal, hexanal, heptanal, octanal, 1-octen-3-ol, and 2-heptanone. The subsequent results showed that the HNW-irrigated rice not only retained lower levels of free fatty acid values, but also had increased antioxidant capacity and decreased lipoxygenase activity and transcripts, thus resulting in decreased lipid peroxidation. This study opens a new window for the practical application of HNW irrigation in the production and subsequent storage of crops.

Pig Slaughterhouse Wastewater: Medium Culture for Microalgae Biomass Generation as Raw Material in Biofuel Industries

Microalgae are photosynthetic microorganisms with high lipid content, capable of degrading nutrients from wastewater. In this research, two strains of microalgae, Scenedesmus sp. and Chlorella vulgaris were cultivated in sterilized pig slaughterhouse wastewater using outdoor flat photobioreactors. Cell growth, total lipids, free fatty acids (FFA), fatty acid methyl esters (FAME) and physicochemical parameters of wastewater were measured. The results indicated that pig slaughterhouse wastewater is adequate to grow these species of microalgae, obtaining a higher biomass growth for Scenedesmus sp. compared to Chlorella vulgaris (0.41 g/L vs. 0.2 g/L); additionally, these species can be used in bioremediation processes due to the nutrient removal achieved in terms of Total Nitrogen (TN), Total Phosphorous (TP) and Total Organic Carbon (TOC). Methylcyclohexane, chloroform: methanol (1:2) and ethyl acetate had better yield of lipids and FFA. The percentages of FAMEs from FFA were in the range of 52.5–89.5 wt% for Scenedesmus sp. and for Chlorella vulgaris from 52–80.5 wt%. Although the values of lipids, FFA and FAME are below of the range reported by other authors, the use of this type of wastewater as culture medium for the two species cannot be ruled out for lipid extraction in biofuel production.

The Combined Effects of Bio-Components and Alginate Coating on Chemical and Sensory Quality of Chill-Stored Rainbow Trout Fillets

ABSTRACT The objective of the present study was to reduce lipid oxidation and preserve sensory quality of fish fillets maintained under refrigerator condition. The lactoperoxidase system (LPOS) or Zataria multiflora Boiss essential oil (ZEO) was added individually or in combination in biodegradable coatings. Fish fillets were analyzed for peroxide value (PV), free fatty acid value (FFA), fatty acid profile, thiobarbituric acid reactive substances (TBARS) value, and sensory evaluation. Suppressive effect of ZEO and LPOS was seen in the combined groups; so that PV value ranged from 0.32 (0 day) and 0.41 (4 day) meq/kg to 1.97 meq/kg on day 8. The lowest amount of TBARS (1.54 mg MDA/kg) and FFA (1.84% of oleic acid) was obtained in the samples treated with alginate coating containing LPOS and ZEO 1% at the end of storage. The use of ZEO and natural preservatives such as LPOS is presented as alternatives to chemical preservatives in seafood.

Comparative Study on Frying Performance of Three Different Oils for the Preparation of Ripe Plantain Banana

In this study, the effect of traditional frying on oils degradation namely frial oil (FO), soybean oil (SBO) and refined blanded deodorized palm olein oil (RBDPOo) was investigated. Oils degradation was monitored by measuring the free fatty acids (FFA), peroxides (PV), p-anisidine (p-AV),) iodine value (IV), totox value (TxV), total polar compounds (TPC), fatty acid composition and C18:2/C16:0 ratio, viscosity, conjugated dienes (CD) value and oil color. Oils samples were taken every 4 h of frying during 10 consecutive days. Values of all physic-chemicals measures significantly changed with frying and type of fat. Values of FFA, p-AV, TPC, CD, TxV, ΔE and viscosity increased significantly, whereas IV and C18:2/C16:0 ratio decreased significantly at the end of the frying processes. Excepted PV, where the values reached a maximum and then decreased at to final frying. These results suggested that a traditional frying process has an impact on degradation on edible oils.

Determination of Maximum Oil Yield, Quality Indicators and Absorbance Spectra of Hulled Sunflower Seeds Oil Extraction under Axial Loading

The present study aims to estimate the maximum oil yield of hulled sunflower seed samples in a uniaxial process under a load of 40 kN and speed of 4 mm/min. The oil samples were assessed for their quality parameters and spectra curves within the wavelength range of 325–600 nm. The results show that heating temperatures in the range of 40 °C to 80 °C increased the oil output; however, a maximum oil yield of 48.869 ± 6.023% with a minimum energy of 533.709 ± 65.644 J at the fifth repeated pressing was obtained from the unheated sample compared to the heated samples. The peroxide values ranged from 6.898 ± 0.144 to 7.290 ± 0.507 meq O2/kg, acid values from 1.043 ± 0.166 to 1.998 ± 0.276 mg KOH/g oil and free fatty acid values from 0.521 ± 0.083 to 0.999 ± 0.138 mg KOH/g oil, which were within the recommended quality threshold. There were significant spectral differences among the oil samples. A single absorbance peak was observed at 350 nm for all oil samples, indicating low levels of pigment molecules in the oil. The study revealed the need for repeated pressings to recover the considerable residual oil remaining in the seedcake after the first pressing.