**2. Importance of physical and chemical characteristics of cultivated tropical fruits**

Quality is defined as the absence of defects or degree of excellence and it includes appearance, color, shape, injuries, flavor, taste, aroma, nutritional value and being safe for the consumer (Abbott, 1999). Due to a higher market exigency as for high quality products, the juice and pulp industries have been looking for fruits with better internal and external features, including fruit length and width; fruit weight; pulp, seed and peel percentages per fruit; number of seeds per fruit; seed size and peel diameter; soluble solids (ºBrix); titratable acidity (%); vitamin C content (mg/100g of fresh fruit); pulp pH and soluble solids/titratable acidity ratio.

The maintenance of fruit quality characteristics (internal and external features above cited) demands postharvest handlings, such as: preventing mechanical injury, water loss and disease development, limiting unwanted physiological changes and preventing chemical and microbial contamination (Cook, 1999). It is important to mention that farmers, packers,

Physical and Chemical Characteristics of Tropical and Non-Conventional Fruits 5

Underutilized citric fruits also have been studied in Brazil aiming to provide, to orange industry, new options. One of these species is sour orange (*Citrius aurantium* L.; Figure 2), generally more consumed by people in Piaui State (Northeasthern Brazil) as for juice or fresh fruit than common orange (*Citrus sinensis* L.) cultivars. Silva Júnior et al. (2010) evaluated the physical and chemical properties of "laranja da terra" (in English, "native orange") fruits and concluded that its fruit presents good physico-chemical properties, with an average of 125.76 mg/100g of fresh fruit, indicating that it is a good natural source of vitamin-C; "laranja da terra" fruits present low titratable acidity and high soluble solids, so they have a great potential for consumption as fresh fruit. Further studies are necessary to determine the technological parameters for its consumption as fresh or processed fruit.

It is important to detach that, orange fruit maturation considers, mainly, the concentration of soluble solids (ºBrix) and titratable acidity (%), while soluble solids: titratable acidity ratio (SS/TA ratio) of 12 (Di Giorgi, 1990), in a general way, is required for orange harvest aiming

Another important fruit for industry is acerola (*Malpighia glabra*) also known as Barbados cherry. The importance of this species is directly related to the chemical and nutritional status of its fruits, especially vitamin C content, which has motivated the expansion of the cultivated area and has increased the demand for acerola in the world market. On the other hand, vitamin C content of acerola fruits depends on plant genetics since, according to Cavalcante et al. (2007a), high variability in fruit quality is observed in Brazilian acerola crops, especially those propagated by seeds. In this area, Cavalcante et al. (2007a) developed a research work with the objective of evaluating physical and chemical characteristics of fruits of sixteen acerola genotypes in Jaboticabal, São Paulo State, Brazil, and they have observed that eleven groups were formed, what indicates high variability among the acerola genotypes studied in relation to fruit quality parameters. This way, some genotypes presented potential for consumption as fresh fruit and others for industry. Figure 3 shows acerola fruits of genotype ACER-3, which presented almost 1.200 mg of vitamin C in 100g of fresh fruit, fruits with 6.9 ºBrix, 0.73% of titratable acidity, pulp percentage of 47% and fruit

pasteurized juice industry and focusing the more profitable harvest time for farmers.

Fig. 2. Sour orange (*Citrus aurantium* L.) fruit.

weight 6.82g.

shippers, wholesalers, retailers and consumers frequently have different perspectives regarding to quality and often place different emphasis on the different components of quality. In addition to that, Paull & Duarte (2011) reported that fruit quality is related to some intrinsic characters (appearance, colour, acids, sugars, etc.) and since they change during handling research data can give us information on the waya product should be handled postharvest.

Inherently, the demand of fruit quality, physically and chemically talking, by industries, depends on fruit species and the product processed by each one of them.

Orange juice industry requires fruits for processing during all months of the year, what can be considered a great problem since the most cultivated orange cultivars in São Paulo State are, for instance, Hamlin, Natal, Pera and Valencia (Cavalcante et al., 2009a), whose production is concentrated in few months, fact that makes the commercial activity vulnerable to incidence of harmful diseases and concentrated juice price fluctuations. This way, lots of research work have been developed aiming the expansion of harvest time through new cultivars, with different fruit maturation curves as for the most recently cultivated ones, such as Cavalcante et al. (2006b), which has established a physical and chemical characterization of eighteen orange cultivar fruits and has also concluded that some of them presented potential for consumption as fresh fruit while others are much more appropriate for industry, indicating the importance of diversification.

Cavalcante et al. (2009a) evaluated, under São Paulo State (Brazil) conditions, fruit maturation of 18 sweet orange cultivars and have found that, according to Figure 1, four groups are formed considering its maturation: Orange cultivars João Nunes and Hamlin are the earliest ones, followed by Kawatta, Mayorca, Rubi and Westin; Pineapple and Tarocco A and Oliverlands, Cadenera and Homosassa, respectively; while Torregrosa, Jaffa, Biondo, Finike, Sanguinea, Moro and Early Oblong are the cultivars whose maturation is later than the other ones studied.

Fig. 1. Cluster diagram of sweet orange cultivars, obtained with SS/TA ratio, technological index and fruit mass. Cavalcante et al. (2009a)

shippers, wholesalers, retailers and consumers frequently have different perspectives regarding to quality and often place different emphasis on the different components of quality. In addition to that, Paull & Duarte (2011) reported that fruit quality is related to some intrinsic characters (appearance, colour, acids, sugars, etc.) and since they change during handling research data can give us information on the waya product should be handled postharvest. Inherently, the demand of fruit quality, physically and chemically talking, by industries,

Orange juice industry requires fruits for processing during all months of the year, what can be considered a great problem since the most cultivated orange cultivars in São Paulo State are, for instance, Hamlin, Natal, Pera and Valencia (Cavalcante et al., 2009a), whose production is concentrated in few months, fact that makes the commercial activity vulnerable to incidence of harmful diseases and concentrated juice price fluctuations. This way, lots of research work have been developed aiming the expansion of harvest time through new cultivars, with different fruit maturation curves as for the most recently cultivated ones, such as Cavalcante et al. (2006b), which has established a physical and chemical characterization of eighteen orange cultivar fruits and has also concluded that some of them presented potential for consumption as fresh fruit while others are much more

Cavalcante et al. (2009a) evaluated, under São Paulo State (Brazil) conditions, fruit maturation of 18 sweet orange cultivars and have found that, according to Figure 1, four groups are formed considering its maturation: Orange cultivars João Nunes and Hamlin are the earliest ones, followed by Kawatta, Mayorca, Rubi and Westin; Pineapple and Tarocco A and Oliverlands, Cadenera and Homosassa, respectively; while Torregrosa, Jaffa, Biondo, Finike, Sanguinea, Moro and Early Oblong are the cultivars whose maturation is later than

Fig. 1. Cluster diagram of sweet orange cultivars, obtained with SS/TA ratio, technological

index and fruit mass. Cavalcante et al. (2009a)

depends on fruit species and the product processed by each one of them.

appropriate for industry, indicating the importance of diversification.

the other ones studied.

Underutilized citric fruits also have been studied in Brazil aiming to provide, to orange industry, new options. One of these species is sour orange (*Citrius aurantium* L.; Figure 2), generally more consumed by people in Piaui State (Northeasthern Brazil) as for juice or fresh fruit than common orange (*Citrus sinensis* L.) cultivars. Silva Júnior et al. (2010) evaluated the physical and chemical properties of "laranja da terra" (in English, "native orange") fruits and concluded that its fruit presents good physico-chemical properties, with an average of 125.76 mg/100g of fresh fruit, indicating that it is a good natural source of vitamin-C; "laranja da terra" fruits present low titratable acidity and high soluble solids, so they have a great potential for consumption as fresh fruit. Further studies are necessary to determine the technological parameters for its consumption as fresh or processed fruit.

Fig. 2. Sour orange (*Citrus aurantium* L.) fruit.

It is important to detach that, orange fruit maturation considers, mainly, the concentration of soluble solids (ºBrix) and titratable acidity (%), while soluble solids: titratable acidity ratio (SS/TA ratio) of 12 (Di Giorgi, 1990), in a general way, is required for orange harvest aiming pasteurized juice industry and focusing the more profitable harvest time for farmers.

Another important fruit for industry is acerola (*Malpighia glabra*) also known as Barbados cherry. The importance of this species is directly related to the chemical and nutritional status of its fruits, especially vitamin C content, which has motivated the expansion of the cultivated area and has increased the demand for acerola in the world market. On the other hand, vitamin C content of acerola fruits depends on plant genetics since, according to Cavalcante et al. (2007a), high variability in fruit quality is observed in Brazilian acerola crops, especially those propagated by seeds. In this area, Cavalcante et al. (2007a) developed a research work with the objective of evaluating physical and chemical characteristics of fruits of sixteen acerola genotypes in Jaboticabal, São Paulo State, Brazil, and they have observed that eleven groups were formed, what indicates high variability among the acerola genotypes studied in relation to fruit quality parameters. This way, some genotypes presented potential for consumption as fresh fruit and others for industry. Figure 3 shows acerola fruits of genotype ACER-3, which presented almost 1.200 mg of vitamin C in 100g of fresh fruit, fruits with 6.9 ºBrix, 0.73% of titratable acidity, pulp percentage of 47% and fruit weight 6.82g.

Physical and Chemical Characteristics of Tropical and Non-Conventional Fruits 7

Another very appreciated tropical fruit specie in North Eastern of Brazil is yellow mombin (*Spondias mombin* L.), a native fruit with expressive potential for food industry in this region, concerning the sensorial quality of its fruit, being a species that should be used for more extensive commercial crops. During the last years, yellow mombin have been commercialized in higher amounts on different commercial sectors and Brazilian regions,

Cavalcante et al. (2009b) evaluated physical and chemical characteristics of yellow mombin fruits [fruit mass, width and length of fruits and seeds, percentages of pulp, skin and seed, water (%), soluble solids, industrial index and pulp pH] for consumption as fresh or processed fruit from natural plants native of North Eastern of Brazil. These authors revealed that yellow mombin fruit mass evaluated varies from 8.36 to 20.4 g; soluble solids and pH are in agreement to the standard market parameter (i.e. SS>9.0 ºBrix and pH>2.2) but pulp percentage of most evaluated counties was below food industry exigency, which standardized the minimum of 60% for pulp percentage. The industrial index for yellow mombin fruits reached 9.0%, pointing out that, for fruit industry, higher industrial indexes are required focusing a prominent possibility of higher soluble solids concentrations. This way, 9.0% is considered a satisfactory index for yellow mombin

Custard apple (*Annona squamosa* L.), also known as sweetsop (English); anon, riñón (Spanish); noina (Thai); nona seri kaya (Malay); custard apple (Indian); and pinha, ata or fruta-do-conde (Portuguese), is a fruit species native of tropical America, occurring spontaneously in Northeastern Brazil, where it is exploited mainly as subsistence without adequate management and without genetic material selection. Custard apple fruit has been usually consumed as dessert, i.e., several custards and fine desserts, which can include combinations with whipped cream and meringues. Adversely, the perishable nature of the fruit and often short supply limits availability to local markets or air shipment to moredistant markets. On the other way, lately, custard apple fruit has been studied for being included among tropical fruits widely used by industry due to its flavor and high concentrations of titratable acidity, which is particularly important for fruit processing,

In a research work on custard apple fruits, Cavalcante et al. (2011b) evaluated yield, physical and chemical characteristics of the fruits of ten sugar apple genotypes in Bom Jesus, Piauí State, Brazil. The best results of the mentioned study have revealed that custard apple fruits presented a relation between longitudinal diameter and transversal diameter of 1.09, what classifies them as good quality fruits, according to the format variable, with an average fruit weight of 203.69 g, 11 seeds per fruit, soluble solids of 22.8ºBrix, titratable acidity of 0.16% and vitamin C of 138.55 mg/100g of fresh fruit; results that characterize custard apple

Tropical fruits are usually sold fresh, and off-grade fruit is processed, exception done for coconut, which is grown mainly for the production of other products, such as copra, oil and coir with a small acreage, often of special varieties that are grown for fresh consumption of its water of albumen, fact that highlights that coconut fruit, among tropical fruits, is classified as a low water moisture loss rate. In Brazil, coconut has been grown preferentially for food industry purposes as for its water of albumen, although fresh water consumption is

mainly due to the possibility of fruit consumption as *in natura* or processed.

reducing the addiction of artificial acid components.

fruits as a natural source of vitamin C.

very appreciated by people.

fruits.

Fig. 3. Acerola fruits of genotype ACER-3 from the Active Germplasm Bank of São Paulo State University, Brazil.

Among the other members of *Caricaceae* family, the cultivated papaya (*Carica papaya* L.) is the only one that belongs to *carica* genus. Papaya fruit is native of tropical America, where it is popular and grows for its small to large melon-like fruit.

In consonance with Paull & Duarte (2011), papaya fruit is a fleshy berry, from 50 g to well over 10 kg, and it superficially resembles a melon, being spherical, pyriform, oval or elongated in shape. Fruit shape is a sex-linked character and ranges from spherical to ovoid in female flowers to long, cylindrical or pyriform (pear-shaped) in hermaphrodite flowers. The skin of the fruit is thin and it is usually green when unripe, turning to yellow or orange when ripe, with flesh total soluble solids ranging from 5% to 19%.

In Brazil, the main papaya production country worldwide (Fao, 2011), papaya has been widely produced aiming its consumption as fresh (mainly) or processed fruit into various products, such as chunks and slices for tropical fruit salads, dehydrated slices, cocktails or processed into puree for juices and nectar base, usually frozen; and as canned nectar, mixed drinks and jams, because the puree of papaya fruit is the basis for the remanufacturing of many products. For papaya fruit evaluation, many studies have been conducted in order to understand the postharvest factors that influence papaya quality just as Bron & Jacomino (2006) and Mesquita et al. (2007), and others have been developed on the importance of an extra variable and on fruit firmness. Better firmness of papaya fruit delays membrane lipid catabolism thus extending storage life of fresh fruits, what could be improved by fruit treatments before its ripening, likeextra calcium supply, the same manner Mahmud et al. (2008) has studied and verified that the infiltration treatment at 2.5% demonstrated the best effect on maintaining fruit firmness. Additionally, the desired effect of calcium infiltration at 2.5% on maintaining fruit firmness may be due to the calcium binding to free carboxyl groups of polygalacturonate polymer, stabilizing and strengthening the cell walls, as explained by Conway & Sams (1983).

Fig. 3. Acerola fruits of genotype ACER-3 from the Active Germplasm Bank of São Paulo

is popular and grows for its small to large melon-like fruit.

when ripe, with flesh total soluble solids ranging from 5% to 19%.

Among the other members of *Caricaceae* family, the cultivated papaya (*Carica papaya* L.) is the only one that belongs to *carica* genus. Papaya fruit is native of tropical America, where it

In consonance with Paull & Duarte (2011), papaya fruit is a fleshy berry, from 50 g to well over 10 kg, and it superficially resembles a melon, being spherical, pyriform, oval or elongated in shape. Fruit shape is a sex-linked character and ranges from spherical to ovoid in female flowers to long, cylindrical or pyriform (pear-shaped) in hermaphrodite flowers. The skin of the fruit is thin and it is usually green when unripe, turning to yellow or orange

In Brazil, the main papaya production country worldwide (Fao, 2011), papaya has been widely produced aiming its consumption as fresh (mainly) or processed fruit into various products, such as chunks and slices for tropical fruit salads, dehydrated slices, cocktails or processed into puree for juices and nectar base, usually frozen; and as canned nectar, mixed drinks and jams, because the puree of papaya fruit is the basis for the remanufacturing of many products. For papaya fruit evaluation, many studies have been conducted in order to understand the postharvest factors that influence papaya quality just as Bron & Jacomino (2006) and Mesquita et al. (2007), and others have been developed on the importance of an extra variable and on fruit firmness. Better firmness of papaya fruit delays membrane lipid catabolism thus extending storage life of fresh fruits, what could be improved by fruit treatments before its ripening, likeextra calcium supply, the same manner Mahmud et al. (2008) has studied and verified that the infiltration treatment at 2.5% demonstrated the best effect on maintaining fruit firmness. Additionally, the desired effect of calcium infiltration at 2.5% on maintaining fruit firmness may be due to the calcium binding to free carboxyl groups of polygalacturonate polymer, stabilizing and strengthening the cell walls, as

State University, Brazil.

explained by Conway & Sams (1983).

Another very appreciated tropical fruit specie in North Eastern of Brazil is yellow mombin (*Spondias mombin* L.), a native fruit with expressive potential for food industry in this region, concerning the sensorial quality of its fruit, being a species that should be used for more extensive commercial crops. During the last years, yellow mombin have been commercialized in higher amounts on different commercial sectors and Brazilian regions, mainly due to the possibility of fruit consumption as *in natura* or processed.

Cavalcante et al. (2009b) evaluated physical and chemical characteristics of yellow mombin fruits [fruit mass, width and length of fruits and seeds, percentages of pulp, skin and seed, water (%), soluble solids, industrial index and pulp pH] for consumption as fresh or processed fruit from natural plants native of North Eastern of Brazil. These authors revealed that yellow mombin fruit mass evaluated varies from 8.36 to 20.4 g; soluble solids and pH are in agreement to the standard market parameter (i.e. SS>9.0 ºBrix and pH>2.2) but pulp percentage of most evaluated counties was below food industry exigency, which standardized the minimum of 60% for pulp percentage. The industrial index for yellow mombin fruits reached 9.0%, pointing out that, for fruit industry, higher industrial indexes are required focusing a prominent possibility of higher soluble solids concentrations. This way, 9.0% is considered a satisfactory index for yellow mombin fruits.

Custard apple (*Annona squamosa* L.), also known as sweetsop (English); anon, riñón (Spanish); noina (Thai); nona seri kaya (Malay); custard apple (Indian); and pinha, ata or fruta-do-conde (Portuguese), is a fruit species native of tropical America, occurring spontaneously in Northeastern Brazil, where it is exploited mainly as subsistence without adequate management and without genetic material selection. Custard apple fruit has been usually consumed as dessert, i.e., several custards and fine desserts, which can include combinations with whipped cream and meringues. Adversely, the perishable nature of the fruit and often short supply limits availability to local markets or air shipment to moredistant markets. On the other way, lately, custard apple fruit has been studied for being included among tropical fruits widely used by industry due to its flavor and high concentrations of titratable acidity, which is particularly important for fruit processing, reducing the addiction of artificial acid components.

In a research work on custard apple fruits, Cavalcante et al. (2011b) evaluated yield, physical and chemical characteristics of the fruits of ten sugar apple genotypes in Bom Jesus, Piauí State, Brazil. The best results of the mentioned study have revealed that custard apple fruits presented a relation between longitudinal diameter and transversal diameter of 1.09, what classifies them as good quality fruits, according to the format variable, with an average fruit weight of 203.69 g, 11 seeds per fruit, soluble solids of 22.8ºBrix, titratable acidity of 0.16% and vitamin C of 138.55 mg/100g of fresh fruit; results that characterize custard apple fruits as a natural source of vitamin C.

Tropical fruits are usually sold fresh, and off-grade fruit is processed, exception done for coconut, which is grown mainly for the production of other products, such as copra, oil and coir with a small acreage, often of special varieties that are grown for fresh consumption of its water of albumen, fact that highlights that coconut fruit, among tropical fruits, is classified as a low water moisture loss rate. In Brazil, coconut has been grown preferentially for food industry purposes as for its water of albumen, although fresh water consumption is very appreciated by people.

Physical and Chemical Characteristics of Tropical and Non-Conventional Fruits 9

In a study about potassium fertilizing of yellow passion fruit, Campos et al. (2007) registered weightier and sweeter fruits in plants submitted to larger amounts of potassium, agreeing with Marschner (2005), who informs us about potassium influence on increasing

The effect of mulching is also confirmed because it reduces soil water loses for atmosphere trough evaporation and, consequently, soil moisture becomes higher on root zone making it possible a better nutrient solubility and availability for plants. Campos et al. (2007) verified increase in fruit soluble solids (ºbrix) from plants grown with soil mulching, with a quantitative difference of 0.2 ºbrix; additionally, Freire et al. (2010) found that soil mulch promoted enhancement on fruit weight, fruit firmness, pulp percentage, pulp pH and ascorbic acid, important variables for fruit industry, specially for yellow passion fruit which

Another important theme on yellow passion fruit quality is the use of saline water for growth and production of this tropical fruit. In tropical regions, where water availability is restricted to low quality in relation to salt contents but climatic and soil conditions are adequate for yellow passion fruit growth, researchers have tried to find alternative managements to make its cultivation viable. North-Eastern Brazil is one of these regions, in which, nowadays, there is an important production of yellow passion fruit, in many cases,

Costa et al. (2001) characterized yellow passion fruit from plants irrigated with different saline levels and concluded that water salinity higher than 3.0 dS m-1 does not affect the external and internal quality of fruits. In the same study, it was reported that fruit quality related to pulp percentage, soluble solids, titratable acidity and vitamin C contents were similar to standardized values for plants irrigated with good quality water. These successful results were possible because, as forthis study, planting pits without coating (R0) and with side coatings (R1; R2; R3; R4; respectively one, two, three and four lateral sides) were used, so plating pits with coating, promoted a better water use and, consequently, better fruits. Accordingly, Cavalcante et al. (2005) found a positive correlation between pit coating and number of fruits and fruit weight, under irrigation with saline water, i.e., coated pits increased fruit production under irrigation with saline water with results compatible to fruit production by plants irrigated with good quality water. Cavalcante et al. (2003) associated soil mulch with saline water levels for yellow passion fruit production and identified that increasing salinity of irrigation water has no effect on fruit quality when soil mulch also was used, it was also noticed that soluble solids (ºbrix), titratable acidity and pulp pH produced under irrigation

with saline water and soil mulching are compatible to low demanding markets.

Yellow passion fruit is also positively affected by organic fertilizers, such as biofertilizers, which are obtained by anaerobic fermentation and could be simple [water + fresh bovine manure] at a ratio of [1:1] (in volume) or enriched [water + fresh bovine manure + a protein mix + nutrient sources], as can be seen in figure 4, adapted from Cavalcante et al. (2011c). During the last years, biofertilizers have emerged as an important component of the integrated nutrient supply system and they have been tested on yellow passion fruit production and nutrition through environmentally better nutrient supplies. It is possible to find in the scientific literature some research work that has studied biofertilizers effects on fruit quality of yellow passion fruit, including the ones under irrigation with saline water. According to Cavalcante et al. (2011a), fruit quality and nutritional status of yellow passion fruit are affected by biofertilizer doses applied; fruit length, width, pulp percentage, skin diameter, mass,

soluble solids of fruits.

is at most consumed in processed forms.

under irrigation with saline water.
