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2.2. Fatty Acid Composition

The main fatty acids in olive oil are oleic (18:1), linoleic (18:2), palmitic (16:0), and stearic acid (18:0). The fatty acid composition is a quality parameter and an authenticity indicator of virgin olive oils []. As shown in , oleic acid displayed the highest content that ranged between 76.60% (Koroneiki from Lesvos) and 71.92% (Kolovi from Lesvos). Linoleic acid ranged between 11.63% (Kolovi from Lesvos) and 5.71% (Koroneiki from Chania), while the corresponding values for palmitic acid ranged between 13.61% (Koroneiki from Chania) and 9.65% (Kolovi from Lesvos). The stearic acid content ranged between 2.76% (Koroneiki from Chania) and 2.20% (Kolovi from Lesvos). The fatty acids, such as palmitoleic (16:1), linolenic (18:3), arachidic (20:0), gadoleic (20:1), and behenic (22:0) acid, were detected in smaller amounts (<0.9%). The content of myristic (14:0), margaric (17:0), heptadecenoic (17:1), and lignoceric (24:0) acid did not exceed 0.1%.

2.3. Classification of EVOOs According to Cultivar

It is evident (a) that samples produced from the Koroneiki cultivar form a distinct group (green area), which is clearly separated from that of Kolovi (red area). The two Koroneiki samples that lie outside the confidence eclipse originated from Lesvos. The two principal components explain 67.7% of the total variance. Examining the loading plot (b), samples from the Kolovi cultivar are positively correlated with the content of γ-tocopherol as well as linoleic (18:2), linolenic (18:3), and gadoleic (20:1) acid. The remaining fatty acids (16:0, 16:1, 18:0, 18:1, 20:0, and 22:0) and squalene correlated positively with the Koroneiki EVOOs. When student’s t-test was applied, it turned out that all variables were statistically significant (p < 0.05) between the two cultivars except from α-tocopherol, implying that its content is not dependent on variety.

2.3. Classification of EVOOs According to Cultivar

The results can be better visualized using a heatmap (). γ-Tocopherol, 20:1, 18:2, and 18:3 are present at higher levels in samples from the Kolovi cultivar and lower in the Koroneiki cultivar. The rest of the components display the opposite pattern, except for α-tocopherol, which does not show a specific pattern between the two cultivars.

4.1. Olive Oil Samples

A total of 68 monovarietal EVOOs were obtained during the harvesting period of 2018–2019 (). They were produced from two cultivars (Kolovi and Koroneiki) in three different geographical regions of Greece (Crete island, Lesvos island, and Peloponnese). The samples were packaged in dark-brown glass bottles and stored at 4 °C until analysis.

Abstract

Virgin olive oil (VOO) is one of the key components of the Mediterranean diet owing to the presence of monounsaturated fatty acids and various bioactive compounds. These beneficial traits, which are usually associated with the cultivar genotype, are highlighting the demand of identifying characteristics of olive oil that will ensure its authenticity. In this work, the fatty acid (FA) composition of 199 VOO samples from Koroneiki, Megaritiki, Amfissis, and Manaki cultivars was determined and studied by chemometrics. Olive cultivar greatly influenced the FA composition, namely, oleic acid (from 75.36% for Amfissis to 65.81% for Megaritiki) and linoleic acid (from 13.35% for Manaki to 6.70% for Koroneiki). Spearman’s rho correlation coefficients revealed differences and similarities among the olive oil cultivars. The use of the forward stepwise algorithm identified the FAs arachidonic acid, gadoleic acid, linoleic acid, α-linolenic acid, palmitoleic acid, and palmitic acid as the most significant for the differentiation of samples. The application of linear and quadratic cross-validation discriminant analysis resulted in the correct classification of 100.00% and 99.37% of samples, respectively. The findings demonstrated the special characteristics of the VOO samples derived from the four cultivars and their successful botanical differentiation based on FA composition.

2.2. Fatty Acid Composition

The dominant FA was oleic acid (C18:1) with the highest concentrations observed in Amfissis (75.36 ± 1.14%) and Koroneiki (74.70 ± 1.58%) VOO samples. Lower levels were detected in Megaritiki (65.81 ± 2.75%) and Manaki (70.15 ± 1.72%) cultivars. Adversely, for the polyunsaturated FA, linoleic acid (C18:2), the highest levels were observed in the Manaki (13.35 ± 1.07%) and Megaritiki (12.51 ± 2.02%) cultivars. The major saturated FAs were palmitic acid (C16:0), determined in the highest concentration in Megaritiki (15.53 ± 1.01%), and stearic acid (C18:0) in Koroneiki (2.78 ± 0.28%) and Manaki (2.63 ± 0.15%) samples. Interestingly, the highest levels of oleic/linoleic acid (C18:1/C18:2) and MUFA/PUFA ratios were observed in the Koroneiki cultivar which indicates a high performance against oxidative deterioration [].

2.2. Fatty Acid Composition

ANOVA and subsequent post-hoc tests between FA in association with botanical origin were performed (). Statistically significant differences were observed among the VOOs based on the levels of palmitoleic acid (16:1) and gadoleic acid (20:1), indicating a strong contribution on the discrimination between the four cultivars. Other FA such as arachidonic acid (20:4) and linoleic acid (18:2) were also significant for the differentiation of VOOs from Koroneiki, Megaritiki, and Amfissis cultivars. From the obtained results it is evident that a further application of chemometric methods to FA composition could be successful for the classification of samples with regard to cultivar.

2.3. Correlation Coefficients

Correlations of FA concentrations from the combination of the four olive oil cultivars as well as in each cultivar separately () were studied using Spearman’s rho correlation coefficients to designate potent similarities and differences between the cultivars. From the combined FA results of the four cultivars, strong positive correlations (p ≤ 0.01) were observed (a) between palmitic acid (16:0)—palmitoleic acid (16:1), arachidic acid (20:0)—behenic acid (22:0), and arachidic acid (20:0)—stearic acid (18:0), while strong negative correlations were observed between gadoleic acid (20:1)—palmitoleic acid (16:1) and gadoleic acid (20:1)—palmitic acid (16:0). A medium to strong antagonistic relationships was detected among oleic acid (18:1)—linoleic acid (18:2), oleic acid (18:1)—palmitoleic acid (16:1), and oleic acid (18:1)—stearic acid (18:0) (). The correlations between palmitic acid (16:0)—palmitoleic acid (16:1) and arachidic acid (20:0)—stearic acid (18:0) have been previously reported from Stefanoudaki et al. [] and Kritioti et al. [] who studied olive oil samples from Mastoides, Koroneiki, and Cypriot (ladoelia) cultivars. The antagonistic relationship between oleic acid (18:1)—stearic acid (18:0) has also been reported by Kritioti et al. [].

2.3. Correlation Coefficients

A high degree of positive correlation coefficients were observed between palmitic (16:0)—palmitoleic acid (16:1) for all cultivars, especially in Manaki VOO samples (d). Differences were observed in arachidic acid (20:0)—behenic acid (22:0), medium to strong correlations were observed in Megaritiki and Amfissis, while in Koroneiki and Manaki were low positive (). Positive correlations of arachidic acid (20:0)—stearic acid (18:0) were detected in all cultivars except from Manaki where the significance level was above 0.01. Strong negative correlations were observed between gadoleic acid (20:1)—palmitoleic acid (16:1) in Manaki and Megaritiki while in Koroneiki and Amfissis the correlations were insignificant. Strong negative correlations were also observed in gadoleic acid (20:1)—palmitic acid (16:0) in all cultivars except for Koroneiki samples. Medium to strong negative correlations of oleic acid (18:1)—palmitoleic acid (16:1) were detected in all cultivars. Strong antagonistic relationships were detected among oleic acid (18:1)—linoleic acid (18:2) in all cultivars except Amfissis, and medium antagonistic relationships were among oleic acid (18:1)—stearic acid (18:0) for Koroneiki and Megaritiki VOO samples. Summarizing the above results, common correlation patterns were detected in the four cultivars for the FA palmitic acid (16:0)—palmitoleic acid (16:1) and oleic acid (18:1)—palmitoleic acid (16:1), while several differences were observed among the remaining FA of this study depicting the differences in each cultivar.

2.4. Principal Component Analysis

The variables that contributed primarily in component 1 () were palmitic (16:0), palmitoleic (16:1), oleic (18:1), stearic (18:0), gadoleic (20:1), arachidic (20:0), behenic (22:0), and linoleic acid (18:2), with the highest contribution observed from palmitoleic (16:1) and oleic (18:1) acid. Arachidonic acid (20:4) mainly contributed to the formation of the second axis, followed by stearic (18:0), lignoceric (24:0), and gadoleic acid (20:1). α-linolenic acid (18:3) had a major contribution in the third component (), palmitic (16:0), linoleic acid (18:2), and lignoceric acid (24:0). Based on the first two principal components a good separation has been achieved for the Megaritiki and Amfissis cultivars. Thus, the FA that participate in the formation of the two axes are successfully contributing to the differentiation of the VOO samples from Megaritiki and Amfissis. Nevertheless, VOO samples from the Manaki cultivar were not clearly separated from the Koroneiki samples. Consequently, other chemometric methods should be applied for their differentiation.

Abstract

Jojoba oil (JO) extracted from seeds has outstanding properties, including anti-inflammatory, antioxidant, and antibacterial activities, and can be stored forlong periodsof time. The unique properties of jojoba oil depend on its chemical composition; therefore, the effect of the jojoba genotype on the chemical properties and active components of the seed oil was evaluated in this study. Oil samples were collected from 15 elite Egyptian jojoba lines. The chemical composition, such as moisture, crude fiber, crude oil, ash, and crude protein of elite lines’ seeds was determined to investigate the variation among them based on the jojoba genotype. In addition, the iodine value was obtained to measure the degree of jojoba oil unsaturation, whereas the peroxide number was determined as an indicator of the damage level in jojoba oil. Fatty acid composition was studied to compare elite jojoba lines. Fatty acid profiles varied significantly depending on the jojoba genotype. Gadoleic acid exhibited the highest percentage value (67.85–75.50%) in the extracted jojoba oil, followed by erucic acid (12.60–14.81%) and oleic acid (7.86–10.99%). The iodine value, peroxide number, and fatty acid composition of the tested elite jojoba lines were compared withthose reported by the International Jojoba Export Council (IJEC). The results showed that the chemical properties of jojoba oils varied significantly, depending on the jojoba genotype.

2.1. Chemical Composition of the JO

The chemical composition of the seeds of elite jojoba lines was determined to study the effect of jojoba genotype on the chemical constituents of the seeds. Notably, the crude oil, moisture, ash, crude protein, and crude fiber contents varied depending on the jojoba genotype properties, as listed in . The results obtained from the chemical composition analysis revealed that S3, S6, and S14 showed higher oil percentage values of 48.11, 48.05, and 48.15, respectively, compared to the other tested lines. In contrast, S2, S4, and S9 had lower oil contents of approximately 42%. Gad et al. reported similar results and found that oil weight represented approximately 52% of the total weight of jojoba seeds. JO, the only unsaturated liquid wax extracted from plant sources in large quantities, has a chemical composition similar to sperm whale oil []. This similarity enhances the applicability of JO as an inexpensive replacement for sperm whale oil. The total protein content of jojoba seeds was determined by a colorimetric method using a Biuret solution. S7 had the highest protein content (12.55%), whereas S1 seeds had the lowest protein content (11.93%) compared to the other lines. Cappillino et al. and Mohamed [,] determined the total protein content of jojoba seeds and found similar protein contents of 15.2 and 14.72%, respectively. Additionally, the moisture percentage in the seeds of the different elite jojoba lines was determined to study the potential variation among these lines based on their chemical constituents. In this respect, there was a notable change in the moisture content rangingfrom 3.4 to 5.2%. The crude fiber content of jojoba seeds differed significantly as the change in jojoba lines was in the range of 9.94–17.74%.

2.3. Fatty Acid Profile

Gadoleic acid (C20:1), also known as gondoic acid, is an unsaturated omega-9 fatty acid. It representsthe main fatty acid in the oil of jojoba seeds and exhibitsthe highest percentage value, ranging from 67.85% to 75.50%, compared to the other fatty acids, as shown in . It is similar to human sebum, which acquires high absorption in the human skin and can thereforemoisturize the skin without a greasy effect []. The high content of gadoleic acid in the oils of elite jojoba lines enhances their applicability in the pharmaceutical and cosmetic industries. In addition, the presence of gadoleic acid, an unsaturated fatty acid, at high concentrations confirmed the high iodine values determined for different elite jojoba lines.

Abstract

Root-knot nematodes (RKNs) are a vital pest that causes significant yield losses and economic damage to potato plants. The use of chemical pesticides to control these nematodes has led to environmental concerns and the development of resistance in the nematode populations. Endophytic fungi offer an eco-friendly alternative to control these pests and produce secondary metabolites that have nematicidal activity against RKNs. The objective of this study is to assess the efficacy of Aspergillus flavus (), an entophyte fungus isolated from Trigonella foenum-graecum seeds, against Meloidogyne incognita in filtered culture broth using GC–MS analysis. Among them, various nematicidal secondary metabolites were produced: Gadoleic acid, Oleic acid di-ethanolamide, Oleic acid, and Palmitic acid. In addition, biochemical compounds such as Gallic acid, Catechin, Protocatechuic acid, Esculatin, Vanillic acid, Pyrocatechol, Coumarine, Cinnamic acid, 4, 3-indol butyl acetic acid and Naphthyl acetic acid by HPLC. The fungus was identified through morphological and molecular analysis, including ITS 1–4 regions of ribosomal DNA. In vitro experiments showed that culture filtrate of A. flavus had a variable effect on reducing the number of egg hatchings and larval mortality, with higher concentrations showing greater efficacy than Abamectin. The fungus inhibited the development and multiplication of M. incognita in potato plants, reducing the number of galls and eggs by 90% and 89%, respectively. A. flavus increased the activity of defense-related enzymes Chitinas, Catalyse, and Peroxidase after 15, 45, and 60 days. Leaching of the concentrated culture significantly reduced the second juveniles’ stage to 97% /250 g soil and decreased the penetration of nematodes into the roots. A. flavus cultural filtrates via soil spraying improved seedling growth and reduced nematode propagation, resulting in systemic resistance to nematode infection. Therefore, A. flavus can be an effective biological control agent for root-knot nematodes in potato plants. This approach provides a sustainable solution for farmers and minimizes the environmental impact.