Tocopherol Contents of Pulp Oils Extracted from Ripe and Unripe Avocado Fruits Dried by Different Drying Systems

1 ） avocado fruit and the variety can influence the Abstract: The tocopherol contents of unripe and ripe avocado fruit oil extracted from Pinkerton, Hass and Fuerte varieties were determined after drying fruit using air, microwave or oven drying methods. The α-tocopherol content changed between 13.70 mg/100 g (microwave-dried) and 28.06 mg/100 g (air-dried) in oil from unripe Pinkerton fruit; between 14.86 mg/100 g (microwave-dried) and 88.12 mg/100 g (fresh) in oil from unripe Hass fruit and between 13.31 mg/100 g (microwave-dried) and 17.35 mg/100 g (oven-dried) in oil from unripe Fuerte fruit. The α-tocopherol contents in oil from ripe Fuerte fruit changed between 13.21 mg/100 g (fresh) and 17.61 mg/100 g (oven-dried). In addition, γ-tocopherol contents varied between 11.55 mg/100 g (air-dried) and 14.61 mg/100 g (microwave-dried) unripe “Pinkerton” fruit; between 11.52 mg/100 g (air-dried) and 15.01 mg/100 g (fresh) in unripe Hass fruit and between 12.17 mg/100 g (air-dried) and 15.27 mg/100 g (microwave-dried) unripe Fuerte fruit. The γ-tocopherol contents ranged from 12.71 mg/100 g (fresh) to 17.40 mg/100 g (oven-dried) in ripe Hass fruit; from 10.29 mg/100 g (fresh) and 17.20 mg/100 g (microwave-dried) ripe Fuerte fruit. α-, β-, γ- and δ-tocopherols could not be detected in ripe fresh Pinkerton fruit. In general, β- and δ-tocopherol could not be detected in most of the unripe and ripe avocado fruit oils. α-Tocopherol and γ-tocopherol contents of dried ripe Fuerte fruit oils were found to be higher compared to those of dried unripe Fuerte fruits.

ally regarded as beneficial in maintaining cardiovascular health 8,9 . Lu et al. 10 observed inhibition of prostate cancer cell growth using a lipophilic extract of avocado fruit.
Hence, different uses of avocado fruit require application of appropriate processing techniques that maintain its functional properties in the final product. Drying is a commonly used and well-known postharvest technology aimed at increasing the shelf life of fruits or vegetables, preserving their quality and stability by reducing water activity and moisture content thereby avoiding spoilage and contamination during storage and making possible their utilization in different products including spices, folk medicine 11 . The content of avocado oil is used as an indicator of the fruit maturation stage prior to harvest 1 and the ripening stage of avocado fruit and the variety can influence the Abstract: The tocopherol contents of unripe and ripe avocado fruit oil extracted from Pinkerton, Hass and Fuerte varieties were determined after drying fruit using air, microwave or oven drying methods. The αtocopherol content changed between 13.70 mg/100 g (microwave-dried) and 28.06 mg/100 g (air-dried) in oil from unripe Pinkerton fruit; between 14.86 mg/100 g (microwave-dried) and 88.12 mg/100 g (fresh) in oil from unripe Hass fruit and between 13.31 mg/100 g (microwave-dried) and 17.35 mg/100 g (oven-dried) in oil from unripe Fuerte fruit. The α-tocopherol contents in oil from ripe Fuerte fruit changed between 13.21 mg/100 g (fresh) and 17.61 mg/100 g (oven-dried). In addition, γ-tocopherol contents varied between 11.55 mg/100 g (air-dried) and 14.61 mg/100 g (microwave-dried) unripe "Pinkerton" fruit; between 11.52 mg/100 g (air-dried) and 15.01 mg/100 g (fresh) in unripe Hass fruit and between 12.17 mg/100 g (air-dried) and 15.27 mg/100 g (microwave-dried) unripe Fuerte fruit. The γ-tocopherol contents ranged from 12.71 mg/100 g (fresh) to 17.40 mg/100 g (oven-dried) in ripe Hass fruit; from 10.29 mg/100 g (fresh) and 17.20 mg/100 g (microwave-dried) ripe Fuerte fruit. α-, β-, γ-and δ-tocopherols could not be detected in ripe fresh Pinkerton fruit. In general, β-and δ-tocopherol could not be detected in most of the unripe and ripe avocado fruit oils. α-Tocopherol and γ-tocopherol contents of dried ripe Fuerte fruit oils were found to be higher compared to those of dried unripe Fuerte fruits.
Key words: avocado varieties, fruit drying, fruit oil, tocopherols, HPLC composition and contents of different nutrients in avocado oil 2 . It would be interesting to carry out detailed analytical study of tocopherols in relation of fruit maturation, varieties and drying method used to process the avocado fruit. Therefore, current study was aimed at characterization of tocopherol contents of unripe and ripe avocado fruit oils extracted from three different varieties Fuerte, Hass and Pinkerton after drying using three distinctive techniques, namely air-, microwave-and oven-drying methods.

Material
Avocado fruits were harvested from Fuerte, Hass and Pinkerton varieties at two different maturity stages unripe and ripe in Antalya, Turkey. Avocado fruits were cut to separate pulp from seed and peel fractions.

Samples
Avocado fruit pulp samples from each variety ripe and unripe were divided into 4 groups: Group 1: Control group consisting of untreated pulp Group 2: Room temperature dried pulp Group 3: Microwave oven 540 W, 15 min dried fruit pulp Group 4: Oven 60 , 19 h dried pulp These experimental conditions were selected after preliminary drying treatments in which the final pulp moisture content was maintained at less than 5 .

Analysis for tocopherol contents
Quantification for tocopherol contents was carried out following Spica et al. 12 procedure. Oil was extracted from pulp samples from different varieties using Soxhlet system and 0.1 g of it was mixed with 5 mL of n-hexane followed by filtration using 0.45 µm nylon filter. Tocopherol analyses was accomplishing using a Shimadzu-HPLC system that consisted of a PDA detector and LiChroCART Silica 60 4.6 250 mm, 5 µ; Merck, Darmstadt, Germany column. An isocratic chromatographic separation of tocopherols was carried out using 0.7 propan-2-ol in n-hexane as mobile phase which set to flow at 0.9 mL/min rate. The sample injection volume was set as 20 µL and detection and identification of peaks was carried out at 295 and 330 nm wavelength set at PDA detector following a 30 min running time for each sample. Chromatography standards were prepared using 0-100 mg of α, β, γ and δ-tocopherols per 1 L of solutions prepared following same procedure as explained for oil samples. All the chemical used were of analytical grade and each treatment and measurement of tocopherol sample was carried out in triplicates.

Statistical analyses
The experiments were carried out according to a com-plete randomized split plot block design and obtained data was subjected to analysis of variance ANOVA using JMP software v 9.0, SAS Inst. Inc., Cary, N.C.U.S.A . All analytical measurements were carried out in triplicates and results were expressed as means standard deviations MSTAT C for each independent avocado fruit variety sample 13 .

Results and Discussion
Tocopherol contents of oils obtained from fruit pulp from three different unripe and ripe avocado varieties Hass , Fuerte and Pinkerton dried using different drying systems are presented in Table 1. The α-tocopherol contents changed between 13.70 mg/100 g Microwave and 28.06 mg/100 g Air drying in unripe Pinkerton fruit pulp oil and between 14.86 mg/100 g Microwave and 88.12 mg/100 g Fresh in unripe Hass fruit oils. In addition, α-tocopherol contents of ripe Pinkerton fruit oil were determined between 0.0 fresh and microwave and 19.40 mg/100 g Oven while α-tocopherol contents of ripe Hass fruit oil varied between 0.0 microwave and oven and 53.05 mg/100 g fresh . Similarly, α-tocopherol contents was determined between 13.31 mg/100 g microwave and 17.35 mg/100 g oven in unripe Fuerte fruit pulp oil and between 13.21 mg/100 g fresh and 17.61 mg/100 g oven in ripe Fuerte fruit oils. In addition, γ-tocopherol contents of unripe Pinkerton fruits varied between 11.55 mg/100 g air and 14.61 mg/100 g microwave while that of ripe Pinkerton fruit oils were determined between 11.55 mg/100 g air and 15.57 mg/100 g oven . Additionally, γ-tocopherols of unripe Hass fruit oils changed between 11.52 mg/100 g air and 15.01 mg/100 g fresh while that of ripe Hass fruit oils ranged from 12.71 mg/100 g fresh to 17.40 mg/100 g oven . The γ-tocopherol contents of unripe Fuerte fruit oils were detected between 12.17 mg/100 g air and 15.27 mg/100 g microwave while that of ripe Fuerte oils varied between 10.29 mg/100 g fresh and 17.20 mg/100 g microwave . The α -, β -, γ -and δ-tocopherols in ripe fresh Pinkerton oil were not detected. In general, βand δ-tocopherols could not be detected in most of the oil samples from unripe and ripe avocado fruit. Drying affected tocopherol contents of avocado fruit pulp depending on the varieties and maturation stages. The α and γ-tocopherol contents of ripe Fuerte fruits dried by air, microwave and oven were found to be higher compared to their values for unripe Fuerte fruits dried using same drying methods. βand δ-tocopherols were observed in unripe Fuerte oil dried by air drying. Statistically significant differences were identified among tocopherol contents of ripe and unripe avocado fruit oils p 0.05 Fig. 1a-v . Peraza-Magallanes et al. 14 reported that fresh Hass pulp oil contained 45.02-50.66 µg/g of α-tocopherol. The α-tocopherol contents in the unsaponifiable fraction of Fortuna avocado pulp oils obtained after using different pulp drying techniques and extraction methods changed between 0.55 and 1.25 . In general, α-tocopherol losses can be associated with oxidative stress 15 . Saldeen and Saldeen 16 reported that the mixture of α-, γ-, and δ-tocopherols showed better antioxidant and anti-inflammatory effects in comparison to α-tocopherol using animal models in a limited number of preliminary clinical investigations. Tocopherols are commonly used as antioxidants because they donate hydrogen from the hydroxyl group to the peroxyl radical 17 . Microwave technologies is one of the new techniques for drying of fruits and their pulps and it was furthermore reported to prevent browning of avocado pulp during blanching process 18 . The α-tocopherol is considered as a scavenger of free radicals, thereby inhibiting the oxidation of both fats and phytosterols and persevering the oil quality over longer period of time 15, 19, 20 22 . Results presented in the current study vary from those reported in literature values and these variations can be attributed to the maturation stage of avocado fruit, geographic location, climatic factors, genetic structure and agricultural factors. Individual tocopherols showed marked variations in terms of their sensitivities to different drying methods. Most of the drying techniques caused reduction in α-tocopherol contents weather in ripe or unripe fruit pulp from Hass and Pinkerton avocado whereas it showed significant increments in Fuerte pulp after drying.

Conclusion
The α-tocopherol contents were generally higher in pulp oil from unripe fruit in comparison to ripe ones. Hass variety fruit pulp showed higher α-tocopherol contents than other two varieties. Variations in tocopherols sensitivity to drying process in different pulp from different avocado fruits may also depend on the structure of each type of tocopherols and such variations can be related with the structural differences among the four different kinds of tocopherols that may determine their stability. Further

Ripe
Fresh Pinkerton studies may also help in identifying the appropriate drying technique using a range of process time and temperature and in relation to other nutrients present in avocado fruit pulp.