HORTSCIENCE 45(1):172–175. 2010. content is much higher than the 4% to 7% oil in the mesocarp of West Indian avocados (Biale and Young, 1971), which are grown in Ripening and Physiological Changes in areas where P. schiedeana is also found. These values are also higher than those the Fruit of Persea schiedeana Nees reported for high oil-containing avocado varieties (Go´mez-Lo´pez, 2002) and are sim- during the Postharvest Period ilar, higher, or much higher than those reported for the fruit of olive cultivars Oscar Andre´s Del Angel-Coronel (Lavee, 1996). The fatty acid composition Instituto Tecnolo´gico Superior de Huatusco, Avenida 25 Poniente No. 100, of the oil is quite variable. The oleic acid Col. Reserva Territorial, Huatusco, Veracruz 94100, Me´xico content ranges from 37% to 60%; this repre- sents the main fatty acid and it is very Juan Guillermo Cruz-Castillo1 important from a nutritional point of view Univ. Auto´noma Chapingo, Centros Regionales-CRUO, Km 6. Carr. (Cruz-Castillo et al., 2007; Joaquı´n-Martı´nez et al., 2007; Rendo´n-Cantillano, 2003). Huatusco-Xalapa, Huatusco, Veracruz 94100, Mexico Genotypes that have fruit with high oil and Javier De La Cruz-Medina oleic acid contents are potentially a source for Unidad de Investigacio´n y Desarrollo en Alimentos, Instituto Tecnolo´gico oil that could be extracted and used in the ´ human diet. Because this fruit is used as food de Veracruz, Avenida Miguel Angel de Quevedo No. 2779, Veracruz 91860, and could be used to extract oil, P. schie- Mexico deana is of interest as a possible special crop. For this, the best genotypes need to be Franco Famiani selected. Dipartimento di Scienze Agrarie e Ambientali, Universita` degli Studi di The fruit is harvested according to the Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy number of days after fruit set (Cruz-Castillo et al., 2007) and the color and the firmness of Additional index words. Mesoamerican fruit, climacteric fruit, perishable fruit, neglected fruit, the fruit evaluated by sight and squeezing the postharvest physiology fruit with the hands. No quantitative (in- strumental) color and firmness data are avail- Abstract. In terms of color, firmness, respiration, and ethylene production during the able that can be used as reference points to postharvest period, ripening is here characterized for the first time in the fruit of Persea determine when to harvest. The ripeness for schiedeana Nees. The results show a respiratory peak (respiratory climacteric) and an the fruit to be eaten is evident from the fruit ethylene production peak, indicating that the fruit of P. schiedeana can be classified as firmness and color (pale green for green- climacteric. The fruit ripened rapidly, and senescence effects appeared 5 days after colored fruit); again, no quantitative refer- harvest. Together with appreciable weight loss during the postharvest period, this makes ence data are available as a measure of eating the fruit very perishable. Preliminary values for quantitative ripening indices are ripeness. provided (fruit firmness, color lightness, hue angle, and chroma). The present study has investigated the fruit characteristics (color and firmness) at the time of harvesting and during the post- Persea schiedeana Nees. is a fruit tree human consumption. P. schiedeana has also harvest ripening as well as the physiological species belonging to the Lauraceae family been used as a rootstock for avocado because processes related to ripening such as respira- that is found from the central part of Mexico it can tolerate attacks of Phytophthora cinna- tion and ethylene production. The results to Panama (Munsell et al., 1950). The trees momi Rands to the root system (Zentmayer obtained allow initial characterization of the grow wild in the mesophile forests, and the et al., 1988). ripening process of the P. schiedeana fruit, fruit is a drupe that is eaten by mammals The fruit of P. schiedeana is called chinı´n provide a better understanding of its physi- (Gallina et al., 1996). P. schiedeana is some- or chinene in Mexico; chucte, chupte, or ology, and are useful to improve its post- times used to produce shade in coffee (Coffea coyou in Guatemala; and shucte or sucte in harvest management. arabica L.) plantations. Honduras. In the Mesoamerican region, i.e., southern The few studies that have been conducted Materials and Methods Mexico, Guatemala, El Salvador, Honduras, on the fruit of P. schiedeana have investi- and Belice, the pulp of the P. schiedeana fruit gated its mineral content (Munsell et al., Tree characteristics and location and is a popular food. When the fruit is mature, the 1950), morphology (length and diameter, fruit sample collection. Fruits of P. schie- pulp is spread on corn (Zea mays L.) tortillas skin and pulp color), weight, and composi- deana (n = 72) were harvested from the south and eaten as a ‘‘taco,’’ and in Guatemala, the tion in terms of dry matter, fiber, and oil side of the canopy of three trees (24 fruits/ mesocarp is also used in black bean soup. This (Cruz-Castillo et al., 2007; Joaquı´n-Martı´nez tree) that produced green-skinned fruit. The fruit is mainly sold in regional markets and et al., 2007). The physical and chemical trees were 30 years old and 18 m high and rarely appears in supermarket chains, also characteristics of the oil and its fatty acid were located in Huatusco, Veracruz, Me´xico because it has a short postharvest life, which composition have also been evaluated (Cruz- (long. 19 10#24$ N, lat. 96 57#45.6$ W) at limits its marketability. Castillo et al., 2007; Joaquı´n-Martı´nez et al., an altitude of 1300 m a.s.l. The fruits were P. schiedeana has not been cultivated on 2007; Rendo´n-Cantillano, 2003). The dimen- harvested in mid-July based on the number of a large scale in orchards (as a monoculture) sions and weight of the fruit vary greatly, days after the fruit set (90 d) (Cruz-Castillo for fruit production, but it is generally culti- ranging from 100 g to 450 g (Cruz-Castillo et al., 2007), the pale green color of the skin vated in home gardens. No cultivars have et al., 2007; Joaquı´n-Martı´nez et al., 2007). (evaluated by sight), and the firmness (eval- been selected for the production of fruit for Different lines of P. schiedeana can be uated by squeezing the fruits with the hands) distinguished according to the skin color of (Fig. 1). the fruit (Joaquı´n-Martı´nez et al., 2007), Postharvest conditions. The fruits from Received for publication 16 July 2009. Accepted which can be black, green, dark red, orange, the three trees were mixed for all of the for publication 16 Nov. 2009. or greenish yellow. The oil content ranges analyses and kept at room temperature (25 1To whom reprint requests should be addressed; from 25% to 36% of the fruit fresh weight ±2 C) at a relative humidity of 80% to e-mail [email protected]. (Joaquı´n-Martı´nez et al., 2007). This oil 85%.
172 HORTSCIENCE VOL. 45(1) JANUARY 2010 Fruit measurements. The fruit firmness were determined first (weight, respiration, hue angle, 40 L and 85 L for lightness, and 23 and color were evaluated at harvest and at 2-d ethylene production, and skin color), and and 25 for chroma corresponding to a bright intervals during the postharvest period. The then the same fruits were used for the de- greenish yellow skin color and a bright yel- firmness was measured by penetrating the structive measurements (fruit firmness and low pulp (Fig. 2). The mean fruit firmness skin and the mesocarp with a handheld pen- mesocarp color). For all of the measure- value was 31 N (Fig. 2). All of these etrometer (Effegi, Ravenna, Italy), with a ments, nine fruits were chosen randomly with parameters changed significantly during the 4-mm-diameter plunger, and expressed in each considered as an experimental unit postharvest period. The mean color purity Newtons; the mean of two equatorial mea- (replication). Experimental data are reported (chroma), lightness (%L), and hue values surements per fruit was considered as one as means ± SE. decreased slightly for up to 3 d (lightness replication. Skin and mesocarp color were and hue angle of skin) and 5 d (lightness and measured at three different equidistant points Results and Discussion hue angle of mesocarp and chroma of both around the equatorial area of the fruit using skin and mesocarp) after harvest, after which a colorimeter (Miniscan XE Plus; HunterLab, Characterization of fruit ripening at they decreased sharply. The skin remained Reston, VA); the mean of the three measure- harvest and during the postharvest period. greenish yellow up to 5 d after harvest and ments was considered as one replication. The At harvest, the mean fruit weight according then became dark brown very quickly; the lightness (L*), hue angle (h), and chroma (C*) to all of the harvested fruit was 180 ± 7.2 g. mesocarp became yellowish to slightly or- values are reported according to MacGuire The mean fruit mesocarp and skin color ange 3 d after harvest and yellowish brown (1992). The fruit weight loss during the post- values were, respectively, 100 and 87 for 5 d after harvest and then it turned brown. harvest period was determined by weighing the fruits daily and was expressed as a per- centage of the initial weight at harvest. Fruit respiration and ethylene production measurements. Gas chromatography was used to determine the CO2 evolution and C2H4 production. A 5890-Series II gas chromatograph was used (Hewlett Packard, Ramsey, NJ) fitted with a 15 m · 0.25-mm Porapak-Q column. Ethylene production was measured using a flame ionization detector, and CO2 was determined with a thermal conductivity detector. The oven, injector, and detector temperatures were 100, 150, and 250 C, respectively. Every 24 h, single fruits were put into 1-L airtight glass con- tainers for 1.5 h with a septum for sampling. One milliliter of the headspace gas was withdrawn and injected into the chromato- graph to determine the ethylene production –1 (mLC2H4/kgÁh ) and respiration (mL CO2/ kgÁh–1) rates. The same column and chro- matographic conditions were used for the C2H4 and CO2 analyses. CO2 at 99% and –1 300 mLÁL C2H4.were used as standards to calculate the amounts of these gases released by the fruit. All of the calculations to de- termine these two gases were according to the method of Saltveit and Yang (1987); they consider the volume of the chamber and the volume and fresh weight of the fruit. Sequence used for fruit analysis and data handling. At the harvest and during the post- harvest period considered, the same samples of fruit were used for all of the measure- ments. The nondestructive measurements
Fig. 1. Green-skinned P. shiedeana fruits used for the study. The scarring of the fruits resulted Fig. 2. Firmness and skin and mesocarp color of P. schiedeana fruits during ripening at 25 C and 80% to from preharvest insect damage. 85% relative humidity. Each point is the mean of nine replicates ± se.
HORTSCIENCE VOL. 45(1) JANUARY 2010 173 The fruit firmness decreased gradually for up (Saltveit, 1993; Shellie and Saltveit, 1993). In perishable (Tucker, 1993). The high respira- to 3 d after harvest, when it reached values of a successive study on melon, the respiratory tory rates measured in the fruit of P. schie- 23 N and then declined sharply (Fig. 2). climacteric was observed in fruit ripened deana can account for the high fruit weight The fruit is ready for consumption when both on and off the plant (Hadfield et al., loss observed during the postharvest period, the skin is green–yellow and the mesocarp is 1995). These authors suggested that the re- because they might be responsible for a sig- yellow–orange, i.e., between 3 and 5 d after spiratory behavior during ripening could also nificant loss of dry matter in addition to that harvest, at a room temperature of 25 C and be cultivar-dependent (Hadfield et al., 1995). of water. Indeed, on a per-day basis (24 h), a relative humidity of 80% to 85%. The However, when the respiratory climacteric the minimum and maximum respiration rates –1 intense browning of both the skin and the occurs with either detached or still attached measured (130 and 550 mL CO2/kgÁh , re- pulp in the last part of the considered post- fruit, it always indicates a turning point in spectively) corresponded to a loss of 1.5 g harvest period (5 to 7 d after harvest) in- terms of fruit ripening and senescence, and so and 6.5 g carbon (C)/kg, respectively. Con- dicated a rapid senescence of the fruit in this it is always important to establish when this sidering that a common C content in plant period of time. happens. tissue can be estimated to account for 30% During the postharvest period, the fruit The respiration and ethylene production to 35% of the dry matter, the amount of C lost showed an intense and constant loss for fresh patterns of P. schiedeana fruit are those of through respiration corresponded to a loss of weight; after 7 d, this decrease in fresh weight a climacteric fruit. The respiration and eth- dry matter of 4.6 gÁkg–1 and 20 gÁkg–1 (i.e., reached 28% of the initial weight (a mean ylene production peaks corresponded to or a daily loss of fruit weight of 0.5% and 2%, loss of 3.8%/day) (Fig. 3). A similar weight slightly preceded the optimum eating ripe- respectively). loss has been seen for other tropical fruits ness (between the third and fifth days after such as litchi (Litchi chinensis Sonn) (Jiang harvest). The high perishability of P. schie- Conclusions and Fu, 1999). However, the weight loss in deana fruit is in agreement with the observa- the present study was much higher than that tion that fruit with high respiratory rates tend The results of the present study indicate of fruit belonging to the same genus such as to ripen very rapidly and hence are the most that the respiratory climacteric occurs in the avocado (Persea americana Mill.) (Ahmed et al., 2007; Cutting and Wolstenholme, 1991; Dixon et al., 2004), for which most of the weight loss was reported to be the result of water loss (Cutting and Wolstenholme, 1991). When this intense fresh weight loss is considered along with the rapid ripening and early appearance of senescence, these indi- cate that the fruit of P. schiedeana is highly perishable. Physiological changes during ripening. Both fruit respiration and ethylene produc- tion reached a peak 3 d after harvest and then declined (Fig. 4). The respiratory and ethyl- ene peaks of P. schiedeana (550 mL CO2/ –1 –1 kgÁh and 880 mLC2H4/kgÁh , respectively) were at least threefold and ninefold higher, respectively, than those reported for avoca- dos (Kader and Arpaia, 2009) and also higher Fig. 3. Weight loss of P. shiedeana fruits during ripening at 25 C and 80% to 85% relative humidity. Each than those reported for soursop (Annona point is the mean of nine replicates ± SE. muricata L.), a highly perishable climacteric –1 fruit (250 mL CO2/kgÁh and 100 mLC2H4/ kgÁh–1) (Bruinsma and Paull, 1984). It is important to note that the respiration intensity of the P. schiedeana fruit was relatively high before and after the observed peak, indicating that the fruit has a relatively intense basal metabolism. Fruit can be classified as either climacteric or nonclimateric based on the respiration pattern and autocatalytic ethylene production during ripening. Climateric fruits show a res- piratory burst (termed the respiratory climac- teric) and pronounced ethylene synthesis during ripening, whereas nonclimateric fruits do not show such increases (Kader, 2002; Tucker, 1993). In climacteric fruits, the peak can correspond to optimum eating ripeness or it can precede or follow this depending on the fruit considered (Tucker, 1993). In a few cases, contrasting results have been reported regarding the occurrence of the respiratory climacteric. In melon and tomato, it has been reported that the respiratory climacteric might be an artifact of harvest (because the climac- teric rise was only seen in the detached fruit and not in the still attached ones) and not Fig. 4. Respiration and ethylene production of P. schiedeana fruits during ripening at 25 C and 80% to a natural phenomena associated with ripening 85% relative humidity. Each point is the mean of nine replicates ± SE.
174 HORTSCIENCE VOL. 45(1) JANUARY 2010 ripening fruit of P. schiedeana, and so this Bruinsma, J. and R.E. Paull. 1984. Respiration (ed.). Postharvest technology of horticultural fruit should be classified among the climac- during postharvest development of soursop crops. Publication 3311. University of California, teric group. fruit, Annona muricata L. Plant Physiol. Division of Agriculture and Natural Resources, 76:131–138. Oakland, CA. During the postharvest period, the P. ´ schiedeana fruit ripens and senescences rap- Cruz-Castillo, J.G., O.A. Del Angel-Coronel, J. De Kader, A.A. and M.A. Arpaia. 2009. Avocado. La Cruz-Medina, and M.C. Joaquı´n-Martı´nez. Produce Facuss. Postharvest technology research idly with an intense weight loss, resulting in 2007. Caracterı´sticas morfolo´gicas y bioquı´mi- and information center. 6 Sept. 2009.
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