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<strong>Journal</strong> <strong>of</strong> <strong>Applied</strong> <strong>Horticulture</strong>, 8(2): 114-116, July-December, 2006Shelf-life and quality <strong>of</strong> apple fruits in response topostharvest application <strong>of</strong> UV-C radiationAppl<strong>Journal</strong>Syavash Hemmaty a,b , Noorollah Moallemi b and Lotfali Naseri caJahad-e-Daneshgahi, Urmia University, Urmia, Iran; b Department <strong>of</strong> <strong>Horticulture</strong>, Shahid Chamran University <strong>of</strong> Ahvaz,Ahvaz, Iran; c Department <strong>of</strong> <strong>Horticulture</strong>, Urmia University, Urmia, Iran. E-mail: syavash.hort@gmail.comAbstractIn this study, UV-C irradiation (1.435×10 -4 w cm -2 ) was used to maintain fruit quality <strong>of</strong> ‘Red Delicious’ and ‘Golden Delicious’apple cultivars during storage. Apple fruits were irradiated in three different treatments (0, 5 and 15 min), and were stored in a coldstorage at 1±1ºC with 85-95% RH for 6 months. At the end <strong>of</strong> storage, irradiated fruits for 15 min had lower pH and total solublesolids/titratable acids ratio and higher titratable acids and firmness than irradiated fruits for 5 min and control fruits. A significantdifference was observed among total soluble solids <strong>of</strong> irradiated ‘Red Delicious’ fruits for 15 min, irradiated fruits for 5 min andcontrol fruits at the end <strong>of</strong> storage. ‘Red Delicious’ apples had lower total soluble solids and total soluble solids/titratable acids ratioand higher firmness than ‘Golden Delicious’ apples after 6 months. Our results showed that UV-C irradiation can be used to reduceloss <strong>of</strong> fruit quality during long period storage <strong>of</strong> apples.Key words: UV-C irradiation, apple, ‘Golden Delicious’, ‘Red Delicious’, fruit quality.IntroductionApple (Malus domestica Borkh.) fruits are commonly storedfor long periods at low temperatures and under controlledatmosphere. During this period, usually quality and nutritionalvalue <strong>of</strong> fruit decreases. A number <strong>of</strong> techniques like prestorageheat treatment (Klein and Lurie, 1992), treatment with chemicalcompounds (Leverentz et al., 2003) and modified atmosphere(Hertog et al., 2001) have been used. However, some chemicalcompounds may pose serious health hazard and environmentalrisks. Additionally, consumers prefer agricultural productswithout chemicals residues and, hence, alternative methods tocontrol postharvest disease and to extend product shelf-life arerequired (Marquenie et al., 2003).UV-C is generally harmful but can produce beneficial effecton horticultural crops at low doses, a phenomenon known ashormesis (the stimulation <strong>of</strong> plant response by low levels <strong>of</strong>inhibitors or stress) (Lukey, 1982). UV-C radiation has beenshown to be a promising postharvest treatment, because it delaysthe ripening process and does not affect quality during storage(Maharaj et al., 1999).Ripening <strong>of</strong> fruit involves complex physiological changes.The ripening process is generally accompanied by increasedpigmentation, sugar, pH, ethylene and decreased firmness,starch and ascorbic acid (Wills et al., 1981). Purohit et al. (2003)concluded that Ber (Zizyphus mauritiana Lamk.) fruits irradiatedfor 6 hours with UV-C radiation had lower TSS and TSS/TA ratioand higher TA than other treatments and control fruits. Maharaj etal. (1999) and Vicente et al. (2004, 2005) also reported increasein fruit firmness due to UV-C irradiation.This experiment was conducted to examine the effect <strong>of</strong> UV-Ctreatment on shelf life and the physico-chemical changes in‘Golden Delicious’ and ‘Red Delicious’ apples.Materials and methods‘Golden Delicious’ and ‘Red Delicious’ apple fruits wereharvested manually on optimal date for commercial harvesting(150 days after full bloom for ‘Red Delicious’ and 170 days afterfull bloom for ‘Golden Delicious’ apples) (Naseri, 2004) from15-years old standard trees from an orchard in Urmia, Iran, during2004-2005 growing year. Fruits <strong>of</strong> uniform shape, size and freefrom fungal infection were selected.UV-C radiation was provided by fluorescent germicidal lamp(30 w, 90 cm) with a peak emission at 254 nm. Irradiation wascarried out under ambient condition for 0, 5 and 15 min. Theintensity <strong>of</strong> radiation was 1.435×10 -4 w cm -2 . Fruits were placedat approximately 25 cm from the lamp and rotated so thattheir blossom and stem ends faced the lamp to ensure uniformirradiation. After irradiation, fruits were stored at 1±1 ˚C and85-95% RH for 6 months. After sampling from cold stored fruits,they were stored for 7 days at 25ºC.Fruit physical and chemical parameters were measuredperiodically after treatment and 45 days storage at 1±1 ˚C plus7 days at 25 ˚C in 12-apples samples per treatment (3 applesper replication) per cultivar. Total soluble solids (TSS) weredetermined with a hand-held refractometer. Titratable acids (TA)was determined by titration with 0.1 N NaOH and expressed as% malic acid (A.O.A.C, 1980). Fruit firmness was determined onopposite sides <strong>of</strong> the fruit after peel removal using a penetrometerwith 8 mm diameter tip. pH was measured with pH meter. TSS/TAratio was also calculated.Completely randomized factorial design with four replicationswas used. Every replicate had 24 fruits. An analysis <strong>of</strong>variance was used to analyze difference between means. TheDuncan’s multiple range test was applied for mean separationat P=0.05.www.horticultureresearch.net, Reprinted from <strong>Journal</strong> <strong>of</strong> <strong>Applied</strong> <strong>Horticulture</strong>
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