Analysis of Chemical Compositions of 15 Different Cold-Pressed Oils Produced in Turkey: A Case Study of Tocopherol Analysis

Quality Changes of Cold-Pressed Black Cumin (Nigella sativa L.), Safflower (Carthamus tinctorius L.), and Milk Thistle (Silybum marianum L.) Seed Oils during Storage

Oils derived from non-traditional seeds, such as safflower, milk thistle, and black cumin seeds, have recently grown in popularity. Seed oil is in high demand due to consumer interest in illness prevention and health promotion through healthier diets that include a high concentration of monounsaturated and polyunsaturated fatty acids and antioxidant phenolic components. This study assessed the quality characteristics of cold-pressed seed oil at three unique storage times: at the beginning of the trial (i.e., before storage), after 2 months, and after 4 months. The results of the performed analyses indicate that the acidity of extracted black cumin, safflower, and milk thistle seed oil fluctuates considerably over time. The highest acidity level change was detected for black cumin seed oil, from 10.26% after the extraction to 16.96% after 4 months of storage at 4 °C. Consequently, changes between pre- and post-storage peroxide concentrations were discernible after four months. Peroxide value in milk thistle and safflower seed oils increased by 0.92 meq/kg and 2.00 meq/kg, respectively, during the assessed storage time, while that of black cumin was very high and fluctuated. The storage period substantially affects oxidative changes and the oxidation stability of the oil. Major changes were observed in the polyunsaturated fatty acids in seed oil during storage. The essential changes were detected in the black cumin seed oil odor profile after 4 storage months. Their quality and stability, as well as the nature of the changes that occur during the storage of oil, require extensive investigation.

Cold-Pressed Pomegranate Seed Oil: Study of Punicic Acid Properties by Coupling of GC/FID and FTIR

Over the last decades, we have witnessed an increasing interest in food-related products containing vegetable oils. These oils can be obtained either by extraction or by mechanical pressing of different parts of plants (e.g., seeds, fruit, and drupels). Producers of nutraceuticals have ceaselessly searched for unique and effective natural ingredients. The enormous success of argan oil has been followed by discoveries of other interesting vegetable oils (e.g., pomegranate oil) containing several bioactives. This work describes the pomegranate fruit extract and seed oil as a rich source of conjugated linolenic acid as a metabolite of punicic acid (PA), deriving from the omega-5 family (ω-5). Through the chemical characterization of PA, its nutritional and therapeutic properties are highlighted together with the physiological properties that encourage its use in human nutrition. We analyzed the composition of all fatty acids with beneficial properties occurring in pomegranate seed oil using gas chromatography (GC) with flame-ionization detection (FID) analysis combined with Fourier transform infrared spectroscopy (FTIR). Pomegranate seed oil mainly consists of 9,11,13-octadic-trienoic acid (18:3), corresponding to 73 wt % of the total fatty acids. Nine components were identified by GC in PSO, varying between 0.58 and 73.19 wt %. Using midinfrared (MIR) spectroscopy, we compared the composition of pomegranate seed oil with that of meadowfoam seed oil (MSO), which is also becoming increasingly popular in the food industry due to its high content of long chain fatty acids (C20-22), providing increased oil stability. From the results of FTIR and MIR spectroscopy, we found that punicic acid is unique in PSO (73.19 wt %) but not in MSO.

Chemical Composition and in vitro Anti-inflammatory Activity of Wheat Germ Oil Depending on the Extraction Procedure

This study aimed to examine the chemical composition of wheat germ oil extracted by three different methods, and to evaluate its inhibitory effect on the cyclooxygenase and proteinase activities. The results showed that the contents of policosanols, tocopherols and phytosterols were affected by the extraction procedure. However, the fatty acid composition of the different oil extracts was nearly the same. Among the tested oils samples, cold pressed oil exhibited the strongest inhibitory activity against proteinase (93.4%, IC₅₀ =195.7 µg/mL) and cyclooxygenase 1 (80.5%, IC₅₀ =58.6 µg/mL). Furthermore, the cold pressed oil had the highest content of octacosanol, β-sitosterol and α-linolenic acid, suggesting that those bioactive compounds could be essential for the potent ani-cyclooxygenase activity. The present data revealed that wheat germ oil contained cyclooxygenase and trypsin inhibitors, which are the promising therapeutic target for the treatment of various inflammatory diseases. Thus, wheat germ oil might be used to develop functional foods and pharmaceutic products for the human health.

Rapid adulteration detection of cold pressed oils with their refined versions by UV-Vis spectroscopy

The aim of this study is the rapid detection of food pressed oils adulteration with their refined versions, using UV–Vis spectroscopy. The study investigates some common oil physico-chemical parameters such are: density, viscosity, refractive index, acid index, peroxide value, saponification index, to detect differences between cold pressed oils versus refined ones, for some food-grade oils found on Romanian market, as well as FT-IR spectroscopy and GC–MS analytical method, obtaining similar results to those presented in the literature data. The difference between some of the obtained results is not relevant for telling the cold-pressed oils from their refined version for adulteration investigation purpose. Colour analysis instead is a very good method to differentiate a cold pressed oil from a refined one. Taking this into account, the cold pressed oils and their refined versions were mixed in different proportions, and their colour properties were analyzed, obtaining linear dependences for a* and b* CIE L*a*b* parameters with cold pressed oil content in the mixture. Dependence equations were proposed.