Quality attributes and fatty acid, volatile and sensory profiles of “Arbequina” hydrosostainable olive oil

molecules Article Quality Attributes and Fatty Acid, Volatile and Sensory Profiles of “Arbequina” hydroSOStainable Olive Oil Lucía Sánchez-Rodríguez 1, Marina Kranjac 2, Zvonimir Marijanovi´c 3, Igor Jerkovi´c 2, Mireia Corell 4,5, Alfonso Moriana 4,5,Ángel A. Carbonell-Barrachina 1,* , Esther Sendra 6 and Francisca Hernández 7 1Department of Agro-Food Technology, Research Group “Food Quality and Safety”, Universidad Miguel Hernández de Elche, Escuela Politécnica Superior de Orihuela, 03312 Orihuela, Alicante, Spain; [email protected] 2Department of Organic Chemistry, Faculty of Chemistry and Technology, University of Split, 21000 Split, Croatia; [email protected] (M.K.); [email protected] (I.J.) 3Department of Food Technology and Biotechnology, Faculty of Chemistry and Technology, University of Split, 21000 Split, Croatia; [email protected] 4Departamento de Ciencias Agroforestales, ETSIA, Universidad de Sevilla, 41013 Sevilla, Spain; [email protected] (M.C.); [email protected] (A.M.) 5Unidad Asociada al CSIC de Uso Sostenible del Suelo y el Agua en la Agricultura (US-IRNAS), 41013 Sevilla, Spain 6Department of Agro-Food Technology, Research Group “IPOA”, Universidad Miguel Hernández de Elche, Escuela Politécnica Superior de Orihuela, 03312 Alicante, Spain; esther[email protected] 7Department of Plant Science and Microbiology, Research Group “Plant Production and Technology”, Universidad Miguel Hernández de Elche, Escuela Politécnica Superior de Orihuela, 03312 Orihuela, Alicante, Spain; [email protected] *Correspondence: [email protected]; Tel.: +349-6674-9754 Academic Editor: Diego A. Moreno Received: 20 May 2019; Accepted: 4 June 2019; Published: 6 June 2019   Abstract: The use of deficit irrigation techniques on olive orchards is the main trend aiming to optimize water savings while improving functional and sensory characteristics of oils from trees under deficit irrigation techniques. The brand hydroSOStainable has been defined for crops produced under water restriction conditions. HydroSOStainable olive oils obtained under two new regulated deficit irrigation and one sustained deficit irrigation treatments in “Arbequina” olive trees were evaluated by analyzing quality parameters, antioxidant activity, total phenol content, fatty acid profile, volatile compounds, and sensory descriptors. Results showed that some of these irrigation strategies improved the phenol content at “moderate” stress levels, slightly enriched the fatty acid profile (~3.5% increased oleic acid and simultaneously decreased saturated fatty acids), and increased some key volatile compounds and also several key sensory attributes. Therefore, hydroSOStainable olive oil may be more attractive to consumers as it is environmentally friendly, has a higher content of several bioactive compounds, and has improved sensory characteristics as compared to control (fully irrigated) oils. Keywords: total phenol content; oleic acid; regulated deficit irrigation; sustained deficit irrigation; antioxidants; fatty acids 1. Introduction Olive trees were extended all over the Mediterranean countries by eastern civilization. Local wild trees were protected by families and tribes; thus, during many years, those olive trees that were Molecules 2019,24, 2148; doi:10.3390/molecules24112148 www.mdpi.com/journal/molecules Molecules 2019,24, 2148 2 of 16 well-adapted to environmental conditions were selected for cultivation. Consequently, olive trees are nowadays a traditional crop located in the Mediterranean basin, where originally wild olive trees existed. During the last decades, the demand for olive oil experienced a global increase; hence, it was necessary to increase its production using new intensification agronomic techniques [ 1 ]; one of these techniques was irrigation. This intensification produced an increase in tree growth and yield without affecting the quality of olive oil [1]. The three best-known olive tree varieties for super-high-density systems are “Arbequina”, “Arbosana”, and “Koroneiki”. These cultivars have fast entry into production, tend to yield good annual productions, start bearing at an early age, and have excellent oil quality characteristics [2]. In Spain, olive orchards are nowadays one of the main irrigated crops (818,505 ha), only exceeded by cereals (889,411 ha) [ 3 ]. Water scarcity is one of the main issues all over the world, and it has a clear effect on agriculture. Regulated deficit irrigation (RDI) and sustained deficit irrigation (SDI) are some of the techniques that are being developed to confront this problem. RDI decreases the use of water during some specific growing states of olives, while SDI decreases the water applied in a uniform way during all the growing season [4]. Regarding olive oil quality, the European Union and the International Olive Council have regulations to classify olive oil according to their quality [ 5 , 6 ]. With respect to nutritional and functional quality, it is well known that the lipid profile is one of the main contributors due to the high proportion of monounsaturated fatty acids (MUFAs) of this specific oil. Also, polyphenols have an important role, and, in fact, olive oil is the only food that has an authorized health claim [ 7 ]: “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress.” Volatile compounds are essential to olive oil quality, with both main and minor compounds having important roles on flavor. The odor-active compounds are responsible for the oil aroma, while the minor ones, even when they are below the olfactory threshold, can be used as quality markers as they can be essential to understand degradation or formation reactions dealing with odor-active substances [8]. HydroSOStainable products have been defined as fruits and vegetables cultivated under controlled deficit irrigation treatments, which give them differentiating characteristics that make them unique and environmentally friendly [ 9 ]. HydroSOStainable products provide special characteristics to the final commercial commodities, which are richer in some bioactive compounds and have a higher intensity of key sensory attributes, making them attractive for consumers [ 9 , 10 ]. Several products from olive trees under RDI are being studied as hydroSOStainable; for instance, “Manzanilla” table olives have been studied [ 11 – 13 ]. Arbequina olive oil under water deficit techniques have been previously studied [14–18] , but there is not a clear trend on the effect of irrigation on its quality. At this time, there is not a systematic body of knowledge considering agronomic practices, phenological stage during RDI, climatic constraints, etc. to have a full understanding of the effects of RDI on “Arbequina” oil quality, and further studies looking for the best water saving technique are necessary. Therefore, the aim of this work was to study the effect of (i) two new regulated deficit irrigation (RDI) treatments applied during phase II (pit hardening phase) [ 19 ] and (ii) one sustained deficit irrigation (SDI) treatment on “Arbequina” olive oil composition and properties. olive oil quality parameters (free acidity, peroxide value, and UV absorption characteristics), antioxidant, total phenol content, fatty acid profile, volatile compounds, and descriptive sensory analysis were carried out. 2. Results 2.1. Irrigation Four irrigation treatments were applied to olive trees with different types of stress following crop water status by measuring midday stem water potential. Results of the applied water, stress integral (SI), minimum stem water potential (min ψstem ), yield, and mill oil yield are shown in Table 1. Not statistically significant differences in min ψstem and SI were found. Such lack of results was likely related with a wide variability of data, and min ψstem in control trees (T0) was low due to irrigation Molecules 2019,24, 2148 3 of 16 problems (for a few weeks in July). SI described better the levels of stress reached in the irrigation treatments. SI showed a tendency (p<0.1). Control trees (T0) reached lower levels of stress than deficit irrigation treatments. While Confederation RDI (T2) had the highest stress (182 MPa × day) because of the reduced volume of water applied. Although Optimal RDI (T1) received a higher water volume than the Confederation SDI (T3), T1 water stress was higher because water deprivation was applied during stage II. The treatments did not affect significantly (p<0.05) neither the yield, expressed in kilograms per hectare, nor the oil yield. Table 1. Watering technique conditions, oil technological parameters, antioxidant activity (ABTS + and DPPH·methods), and total phenol content (TPC) of “Arbequina” olive oil. ANOVA†T0 T1 T2 T3 Watering Technique Conditions Applied water (mm) 468 197 160 162 Stress integral (MPa ×day) NS†53.4 152 182 132 Min ψstem (MPa) NS −3.80 −4.00 −4.68 −4.04 Yield (kg ha−1)NS 7287 6902 6316 6764 Oil Yield (% dry weight) NS 28.0 30.4 30.1 33.0 Olive Oil Quality Parameters Acidity index (%) NS 0.31 0.37 0.24 0.31 Peroxide value (meq O2kg−1)NS 9.29 8.07 9.36 10.1 K232 NS 2.15 1.91 2.14 2.02 K270 NS 0.10 0.10 0.11 0.10 ∆K NS −0.03 −0.02 −0.02 −0.02 Antioxidant Activity and Total Phenol Content ABTS+(mmol Trolox eq L−1)NS 0.113 0.098 0.114 0.151 DPPH (mmol Trolox eq L−1)NS 0.233 0.223 0.265 0.282 TPC (mg GAE L−1)*259.8 a‡126.8 b 267.3 a 181.5 ab † NS =not significant at p<0.05; *, significant at p<0.05. ‡ Values of olive oil quality parameters, antioxidant activity, and total phenolic content (TPC) (mean of 12 replications per irrigation treatments) followed by the same letter, within the same row, were not significantly different (p<0.05), according to Tukey’s least significant difference test. Note : Acidity index: Threshold value for extra virgin olive oil (EVOO) is ≤ 0.8%; peroxide value: threshold value for EVOO is ≤ 20 meq O 2 kg −1 ; K 232 : threshold value for EVOO is ≤ 2.5; K 270 : threshold value for EVOO is ≤ 0.22; ∆ K: threshold value for EVOO is ≤ 0.01; (EEC Regulation 2568/91). T0: control (100% ETc); T1: Optimal RDI (RDI during stage II); T2: Confederation RDI (RDI during stage II using water limitation of Guadalquivir hydrographic confederation); T3: Confederation SDI (SDI using water limitation of Guadalquivir hydrographic confederation). ABTS+: azino-bis (3-ethylbenzothiazoline-6-sulfonic acid; DPPH·2,2-diphenyl-1-pirylhydrazyl. 2.2. Analytical Parameters for Olive Oil Grading Analytical parameters for olive oil grading are used to determine oil commercial quality. Following European Regulation [ 5 ], olive oil could be cataloged as extra virgin olive oil (EVOO), virgin olive oil (VOO), or lampante olive oil, which needs to be refined before consumption. EVOO has the highest quality. Results of olive oil grading are shown in Table 1. Acidity index, peroxide value, and UV absorption characteristics were under the limit established by the EU legislation; thus, it could be concluded that all oils evaluated in this study met the criteria to be categorized as EVOOs. 2.3. Antioxidant Activity (ABTS+and DPPH·Methods) and Total Polyphenols Results of antioxidant activity (AA), measured by two methods (ABTS + and DPPH · ), and total phenolic content (TPC) are shown in Table 1. No statistical differences between irrigation treatments were found regarding both AA methods, although a different trend was observed for TPC. Treatment 2 showed the highest value of TPC, while T1 had the smallest one. The correlation between TPC and stress level was studied, and Figure 1shows that this correlation produced a quadratic relationship in which it could be seen that TPV increased as the minimum midday stem water potential decreased until −4 MPa; at this stress level, phenols start to decrease. Molecules 2019,24, 2148 4 of 16 Figure 1. Quadratic correlation between total phenolic content (TPC (mg GAE eq L −1 )) and minimum midday stem water potential (Min ψstem (MPa)). Data shown in this figure are the mean of 12 replications per irrigation treatment. 2.4. Fatty Acids Fatty acids are one of the most important parameters to be analyzed in olive oil, and, in this study, 22 fatty acid methyl esters (FAMEs) were identified (Table 2), providing a very detailed characterization of the composition of the oils. Ten saturated fatty acids (SFAs) were found, with palmitic and stearic acids being the predominant ones. Regarding monounsaturated fatty acids (MUFAs), eight compounds were found, among which, oleic acid was the major one; also, the compounds C18:1 cis-11 and C16:1 cis-9 (palmitoleic acid) had important concentrations. Concerning polyunsaturated fatty acids (PUFAs), five compounds were found, standing out linoleic acid. Table 2. Fatty acid profiles of “Arbequina” olive oil as affected by the irrigation treatment. Compound Concentration (g 100 g−1Olive Oil) ANOVA†T0 T1 T2 T3 1 Tetradecanoic acid (Myristic acid) NS 0.025 0.024 0.022 0.025 2 Pentadecanoic acid NS 0.016 0.018 0.019 0.017 3 Hexadecanoic acid (Palmitic acid) * 19.93 a‡19.06 b 18.96 b 19.05 b 4cis-6-Hexadecenoic acid (Sapienic acid) NS 0.207 0.206 0.196 0.202 5cis-9-Hexadecenoic acid (Palmitoleic acid) NS 3.624 3.254 3.292 3.071 6cis-11-Hexadecenoic acid NS 0.030 0.025 0.023 0.021 7 Heptadecanoic acid (Margaric acid) NS 0.135 0.150 0.161 0.154 8cis-9-Heptadecenoic acid * 0.279 b 0.310 a 0.324 a 0.312 ab 9 Octadecanoic acid (Stearic acid) * 1.880 b 1.970 a 2.039 a 2.052 a 10 trans-9-Octadecenoic acid (Eleaidic acid) NS 0.013 0.020 0.015 0.016 11 cis-9-Octadecenoic acid (Oleic acid) ** 47.38 b 50.13 a 51.29 a 51.00 a 12 cis-11-Octadecenoic acid NS 7.026 6.514 6.537 6.419 13 9,12-Octadecadienoic acid (Linoleaidic acid) NS 0.032 0.031 0.027 0.029 14 9,12-Octadecadienoic acid (Linoleic acid) NS 17.55 15.90 14.76 15.38 15 Eicosanoic acid (Arachidic acid) NS 0.512 0.499 0.497 0.506 16 6,9,12-Octadecatrienoic acid (γ-linolenic acid) NS 0.007 0.010 0.010 0.008 17 cis-11-Eicosenoic acid (Gondoic acid) NS 0.333 0.341 0.339 0.341 18 9,12,15-Octadecatrienoic acid (α-linolenic acid NS 0.902 0.866 0.799 0.794 19 Heneicosanoic acid NS 0.014 0.015 0.014 0.015 20 Docosanoic acid (Behenic acid) NS 0.159 0.155 0.154 0.161 21 Tricosanoic acid NS 0.043 0.040 0.040 0.035 22 Tetracosanoic acid (Lignoceric acid) * 0.101 a 0.091 b 0.090 b 0.091 b ΣSFAs NS 22.29 22.00 21.98 22.09 ΣMUFAs ** 59.78 b 61.66 a 62.81 a 62.17 a ΣPUFAs NS 17.61 15.96 14.82 15.43 Atherogenic index, AI NS 0.326 0.311 0.303 0.308 Thrombogenic index, TI NS 0.520 0.513 0.515 0.517 † NS =not significant at p<0.05; *, **, significant at <0.05 and 0.01, respectively. ‡ Values (mean of 12 replications per irrigation treatment) followed by the same letter, within the same row, were not significantly different (p<0.05), according to Tukey’s least significant difference test. Note : SFAs: saturated fatty acids; MUFAs: monounsaturated fatty acids; PUFAs: polyunsaturated fatty acids. Irrigation treatments induced some differences among the oil composition. In general, the highest content of SFAs was found in control oils, while the smallest one was found in the Confederation SDI (T3) oils. Palmitic acid, the predominant SFA, showed this same pattern (19.93 and 19.05 g Molecules 2019,24, 2148 5 of 16 100 g−1 olive oil for T0 and T3, respectively), as well as lignoceric acid. Regarding the MUFAs content, the Optimal RDI (T1) oil showed a lower value than all deficit irrigation treatments. Oleic acid was affected by the irrigation treatments, having control (47.38 g 100 g −1 olive oil) oils the smallest content in comparison with Optimus RDI (50.13 g 100 g −1 olive oil), Confederation RDI ( 51.29 g 100 g -1 olive oil), and Confederation SDI (51.00 g 100 g −1 olive oil). In the case of cis-9-heptadecenoic acid, all the oils under deficit irrigation increased their concentration in comparison to the control. Finally, and as a general finding, PUFAs were not affected by the irrigation strategies. Results of the atherogenic index (AI) and thrombogenic index (TI) are also shown in Table 2. The oils under study had the smallest indexes compared to different oils [ 20 ], which means that olive oil is one of the most healthy oils as reflected by their low AI and TI indexes. Low AI values represent low possibilities of atheroma formation (the possibility of lipid adhesion to cells of the immune circulatory system); besides, low TI values are associated with low chances of formation of clots in the blood vessels [20]. 2.5. Volatile Compounds Volatile profile and composition of oils under study are shown in Table 3. Alcohols were the main chemical family found in all oils, and an increase of concentration was found in all stressed olive trees as compared to the control one. Confederation SDI (T3) was the oil with the highest alcohol content mainly due to the high contents of several compounds, including ethanol ( 149 mg L-1 olive oil), 3-methylbutan-1-ol (15.7 mg L −1 ), 2-methylbutan-1-ol (31.1 mg L −1 ), pentan-1-ol (12.0 mg L −1 ), (Z)-pent-2-en-1-ol (22.7 mg L −1 ), (Z)-hex-3-en-1-ol (303 mg L −1 ), and (E)-hex-2-en-1-ol (727 mg L −1 olive oil). Optimal RDI (T1) and Confederation RDI (T2) oils also showed an increase in the content of several alcohols (3-methylbutan-1-ol, 2-methylbutan-1-ol, pentan-1-ol, (Z)-hex-3-en-1-ol and (E)-hex-2-en-1-ol) as compared to the control treatment. Regarding aldehydes, the smallest concentration was found in T1 due to a decrease of pentanal, hexanal, (E)-hex-2-enal, and nonanal (0.01, 38.3, 161, and 5.86 mg L−1 , respectively). Similarly, 2-methylbutanal and heptanal experienced a decrease in treatment T3. In general, the ketones content decreased in T1 mainly due to a reduction in the content of pentan-2-one; however, its content increased in oils T2 and T3, while pentan-3-one increased in all stressed olive trees. An intensification of the esters contents was found in T1 and T2 oils, mainly as a result of the increased contents of (Z)-hex-3-enyl acetate and hexyl acetate. Finally, a decrease in hydrocarbons was found in T1 and T3 oils, always as compared to the control, due to significant decreases in the contents of 4,8-dimethylnona-1,7-diene and (E)-4,8-dimethylnona-1,3,7-triene in the T1 oils and of (E)- β -ocimene in the T3 ones. To summarize, the highest total volatile compound contents were those of the Confederation SDI (T3) and Confederation RDI (T2) oil. Therefore, it can be concluded that hydroSOStainable olive oils had higher contents of volatile compounds than oil from fully irrigated trees. Molecules 2019,24, 2148 6 of 16 Table 3. Volatile profile (polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber) of “Arbequina” olive oils as affected by irrigation treatment. RI¥Compound Sensory Descriptor Concentration (mg L−1Olive Oil) ANOVA†T0 T1 T2 T3 V1 <500 Ethanol Alcohol, apple, sweet * 56.3 b‡51.0 b 54.7 b 149 a V2 568 Ethyl acetate Aromatic, bitter, fruity * 11.0 b 13.7 b 0.00 c 41.4 a V3 609 Pentanal Nutty, fruity, vanilla * 12.8 a 0.01 c 9.68 b 11.2 ab V4 659 2-Methylbutanal Apple, fruity, ripe ** 7.00 b 8.93 b 17.1 a 0.01 c V5 677 Pent-1-en-3-ol Butter, fruity, green * 19.7 c 17.0 c 32.5 a 26.0 b V6 684 Pentan-2-one Fruity, apple, pineapple ** 30.8 b 26.9 c 41.4 a 36.3 ab V7 697 Pentan-3-one Bitter, green, mustard * 30.1 c 34.1 bc 39.7 b 49.2 a V8 726 3-Methylbutan-1-ol Sweet, woody, yeast *** 10.2 c 12.1 b 11.3 b 15.7 a V9 730 2-Methylbutan-1-ol Winey, spicy * 14.0 c 20.6 b 21.3 b 31.1 a V10 757 Pentan-1-ol Balsamic, fruity, pungent * 5.52 c 8.07 b 9.30 b 12.0 a V11 762 (Z)-Pent-2-en-1-ol Almond, banana, fruity ** 10.5 b 13.2 b 12.3 b 22.7 a V12 799 Hexanal Apple, banana, grass, green *** 63.1 b 38.3 c 65.9 b 87.3 a V13 848 (E)-Hex-2-enal Almond, apple, astringent *** 373 a 161 c 237 b 187 bc V14 851 (Z)-Hex-3-en-1-ol Apple, banana, fresh, grass *** 198 b 285 ab 279 ab 303 a V15 861 (E)-Hex-2-en-1-ol Apple, flowers, fruity, grass * 237 b 362 ab 360 ab 727 a V16 863 Hexan-1-ol Banana, fruity, soft, tomato NS 388 397 345 368 V17 890 Heptan-2-one Banana, cinnamon, fruity NS 4.51 1.22 3.07 0.00 V18 898 2-propenylcyclopentane NS 9.01 4.47 14.2 8.27 V19 904 Heptanal * 10.0 ab 12.2 ab 16.6 a 8.48 b V20 935 3-Ethylocta-1,5-diene (isomer 1) * 25.4 ab 19.8 b 28.5 a 28.6 a V21 942 3-Ethylocta-1,5-diene (isomer 2) * 26.7 ab 18.6 b 28.5 a 28.3 a V22 998 4,8-dimethylnona-1,7-diene ** 45.8 a 27.7 b 48.7 a 42.3 a V23 1007 (Z)-Hex-3-enyl acetate Green, banana *** 229 b 377 a 357 a 236 b V24 1016 Hexyl acetate Green, fruity, sweet * 70.7 c 112 a 116 a 103 b V25 1019 (Z)-Hex-2-enyl acetate Apple, banana, grape *** 8.41 a 8.35 a 8.85 a 0.87 b V26 1053 (E)-β-Ocimene Sweet, herbal * 22.7 a 10.3 ab 8.96 ab 6.61 b V27 1098 Methyl benzoate Fruity ** 5.65 a 0.21 b 0.01 b 0.87 b V28 1107 Nonanal Apple, coconut, grape * 12.7 a 5.86 b 10.6 ab 8.51 ab V29 1120 (E)-4,8-Dimethylnona-1,3,7-triene - * 14.4 a 9.25 b 13.2 ab 12.9 ab V30 1208 Methylcyclodecane - NS 17.3 7.85 12.7 11.8 ΣAlcohols *** 938 b 1165 ab 1124 ab 1654 a ΣAldehydes *** 478 a 226 b 356 ab 302 ab ΣKetones ** 143 ab 112 b 167 a 162 a ΣEsters *** 324 b 511 a 482 a 382 b ΣHydrocarbons ** 82.9 a 47.3 c 70.8 ab 61.8 b ΣVolatile compounds * 1966 b 2061 b 2200 ab 2562 a † NS =not significant at p<0.05; *, **, ***, significant at p<0.05, 0.01, and 0.001, respectively. ‡ Values (mean of 12 replications per irrigation treatment) followed by the same letter, within the same row, were not significantly different (p<0.05), according to Tukey’s least significant difference test. ¥Retention index. Molecules 2019,24, 2148 7 of 16 2.6. Descriptive Sensory Analysis After the official panel determined the commercial quality of all oils under study as EVOO, (average of 4.0 on fruity attribute), the “Food quality and safety” panel conducted descriptive sensory analysis. The lexicon and reference materials used and the sensory profiles of the studied oils are summarized in Table 4. Regarding the positive attributes of flavor, all olive oils under deficit irrigation shared a lower intensity of both green-herbs note and sourness in comparison with the control oil but increased intensities of almond and walnut notes and sweetness. In the Optimal RDI (T1), a decrease in intensity was found for most of the attributes (fruity-olive, fruity-green, floral, green-grass, and bitter). Concerning the Confederation RDI (T2) oil, fruity-olive, fruity-green, and green-herbs increased, and woody note decreased. Finally, the Confederation SDI (T3) oils also increased the intensity of the fruity-olive and woody notes but decreased that of the green-herbs note. No negative attributes (defects) were found in any of the oils under study. Concerning mouthfeel descriptors, astringency increased in T2 and T3, which could be correlated with increased polyphenol content, and, lastly, viscosity also showed an increase in the T2 and T3 oils. In general, it can be stated that deficit irrigation during phase II of the phenological stage of “Arbequina” affected some attributes, such as fruity, green, and nuts, and the intensity of these attributes reached the highest values in the Confederation RDI (T2) oil, which experienced the highest stress. Therefore, it could be concluded that hydroSOStainable olive oil had a higher intensity of several key attributes than the control. Molecules 2019,24, 2148 8 of 16 Table 4. Descriptive sensory profiles of “Arbequina” olive oil as affected by the irrigation treatment. Descriptor References ANOVA†T0 T1 T2 T3 Flavor (positive attributes) D1 Fruity-olive Canned Ripe Olives, Pitted Black =2.3 Hacendado, Manzanilla Green olives =5.3 *** 3.9 ab‡3.3 b 4.2 a 4.3 a D2 Fruity-green (under-ripe olive) Canned Ripe Olives, Pitted Black =1.0 Hacendado, Manzanilla Green olives =2.7 * 2.6 ab 2.2 b 3.0 a 2.6 ab D3 Fruity-ripe (ripe olive) Canned, Ripe Olives, Pitted Black =1.0 Hacendado, Manzanilla Green olives =3.7 NS 1.50 1.75 1.63 1.75 D4 Floral Pompadour, Chamomile Herbal Tea =5.0 Carrefour, White Grape Juice (diluted 1:1) =4.7 * 1.3 a 0..8 b 1.2 a 1.3 a D5 Green-artichoke Hacendado, Artichoke Hearts =3.0 NS 0.8 0.5 0.6 0.7 D6 Green-avocado Under-ripe Fresh Avocado =5.3 NS 0.5 0.5 0.5 0.6 D7 Green-banana Under-ripe Green Banana =4.0 NS 0.40 0.38 0.34 0.31 D8 Green-herbs Verdifresh Arugula (organic, washed) =5.7 * 2.2 a 1.3 b 1.6 b 1.6 b D9 Green-grass Cis-3-Hexen-1-ol 1000 ppm=10.0 * 1.3 ab 0.8 b 1.5 a 0.9 b D10 Green-peppery Hacendado, Green-Peppercorns (dried) =2.0 NS 0.6 0.5 0.6 0.5 D11 Apple Fuji Apple =5.0 NS 0.1 0. 0.21 0.4 D12 Buttery Under-ripe Fresh Avocado =4.0 NS 0.9 0.7 0.7 0.9 D13 Almond Hacendado, almonds =5.0 * 0.3 b 0.4 a 0.4 a 0.5 a D14 Walnut Hacendado, walnuts =6.0 * 0.2 b 0.5 a 0.4 a 0.4 a D15 Woody Hacendado, walnuts =3.0 * 0.4 ab 0.5 a 0.4 b 0.6 a D16 Piney Hacendado, pine nuts =3.5 NS 0.4 0.5 0.5 0.5 D17 Sweet 1% sucrose solution =3.0 * 0.8 b 1.4 a 1.3 a 1.4 a D18 Sour 0.05% citric solution =2.5 ** 0.8 a 0.4 b 0.6 b 0.6 b D19 Bitter 0,01% caffeine solution =1.0 ** 0.8 a 0.5 b 0.7 a 0.9 a Flavor (negative attributes) D20 Oxidized La Masía, 100% sunflower oil a=4.0 NS 0.00 0.00 0.00 0.00 D21 Painty Hacendado, Green-Peppercorns (dried) =3.3 NS 0.00 0.00 0.00 0.00 D22 Rancid International olive council standard =9.2 NS 0.00 0.00 0.00 0.00 D23 Musty International olive council standard =4.65 NS 0.00 0.00 0.00 0.00 D24 Muddy International olive council standard =7.9 NS 0.00 0.00 0.00 0.00 Mouthfeel D25 Astringent 0,10% alum solution =4.0 *** 0.9 b 0.7 b 1.9 a 1.2 ab D26 Pungent Verdifresh Arugula (organic, washed) =5.0 NS 2.7 2.5 2.6 2.9 D27 Viscosity Hacendado, condensed milk =10.0 *** 3.9 b 3.3 b 4.2 a 4.2 a † NS =not significant at p<0.05; *, **, ***, significant at p<0.05, 0.01, and 0.001, respectively. ‡ Values (mean of 12 replications per irrigation treatment) followed by the same letter, within the same row, were not significantly different (p<0.05), according to Tukey’s least significant difference test. Molecules 2019,24, 2148 9 of 16 2.7. Pearson Correlation In order to study the correlation between the accumulative stress in the trees and all the studied functional and sensory parameters, Pearson correlation was done with SI, and significant results are compiled in Table 5. Regarding fatty acids, a positive correlation was found between the SI and C17:1 cis and a negative correlation with linoleic and the total content of SFAs, meaning that the higher the stress, the better the fatty acid profile (an increase of MUFAs and decrease of SFAs). Regarding volatile compounds, a negative correlation between the SI and the aldehydes was found, but the correlation was positive for the total ester content and six compounds of this chemical family (2-methylbutanal, 2-methylbuan-1-ol, (Z)-hex-3-en-1-ol, (Z)-hex-3-enyl acetate, hexyl acetate, and (Z)-hex-2-enyl acetate), which are associated with increased intensity of key aroma notes, such as apple, fruity, sweet, fresh, green, and grass. Finally, green-herbs and sour showed a negative correlation with the SI, although almond, walnut, sweet, and astringency were positively correlated with the SI. Table 5. Pearson correlation between Stress Integral (SI) and fatty acids, volatile compounds, and descriptive sensory analysis attributes. SI Fatty Acids C17:1 cis 0.546†* Linoleic (C18:2 cis)−0.568* SFAs −0.562* Volatile Compounds 2-Methylbutanal 0.657** 2-Methylbutan-1-ol 0.559* (Z)-Hex-3-en-1-ol 0.670** (Z)-Hex-3-enyl acetate 0.778** Hexyl acetate 0.729** (Z)-Hex-2-enyl acetate 0.602* ΣAldehydes −0.706** ΣEsters 0.871*** Descriptive Sensory Analysis Green-herbs −0.841*** Almond 0.834*** Walnut 0.811*** Sweet 0.881*** Sour −0.849*** Astringent 0.603* †*, ** and ***, significant at p<0.05, 0.01, and 0.001, respectively. 3. Discussion Olive oil classification (EVOO) was not affected by RDI/SDI, in agreement with results from previous studies about water deficit irrigation on olive trees [ 14 , 18 , 21 , 22 ]. Description of water stress was not clear with all parameters measured and could affect some of the relationship proposed. Min ψstem was affected for variability within treatments and defined timely water stress, but presented a good agreement with some oil features. Although this measurement was not the most accurate for described irrigation treatments, it could be useful in order to describe oil features because of the reported extreme conditions. On the contrary, SI, though was also limited in comparison to irrigation treatments, it presented clear trends but did not influence the oil features. In the literature on irrigation, both indicators presented a good agreement with some yield components, such as fruit drop [ 23 ]. From our knowledge, there are very few works with the presented relationship between these water status parameter and oil features, probably because of these problems of variability. Molecules 2019,24, 2148 16 of 16 29. 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