Variation of Sugars Distribution in Various Parts of Pitaya (Hylocereus Undatus Britt

(17) Food Preservation Science VOL. 24 NO. 6 1998 (Research Note] 369

Variation of Sugars Distribution in Various Parts of Pitaya (Hylocereus undatus Britt. et Rose)

Wu, Ming Chang* and CHEN , Chin Shu **

* Department of Food Science and Technology , National Pingtung University of Science and Tchnology 1, Hseuh Fu Rd . , Nei Pu, Pingtung , Taiwan 91207 , China ** University of Florida-CREC , 700 , Experiment Station Rd . , Lake Alfred , FL 33885 , USA

Pitaya (Hylocereus undatus Britt. et Rose) is in the Cactaceae family and is native to and and

semiarid regions. Pitaya fruits have 17•`19•‹ Brix and are a good source of minerals, glucose,

fructose, dietary fiber and vitamins. They are normally consumed fresh or preserved in jams,

syrups, or candies, and their juices can be used as a drink base with other beverages or used in

flavorings and food colorings. Because pitaya can withstand prolonged drought, it is considered

to be a potential economic crop for semiarid regions. Soluble solids and enzyme activities in the

core part, stylar-end, and peripheral part of the fruit were determined for varieties Vietnam

(white flesh) and Hsian Lung (red flesh) . The predominant sugars in the fruit are glucose and

fructose. The patterns of sugar distribution in various parts were closely related to invertase

activity and amylase activity in the tissues. The high ratio of glucose to fructose was attributed to the hydrolysis of starch by amylase. (Received Aug. 31, 1998)

Pitaya (Hylocereus undatus Britt. et Rose) is in Mexico ,Centra America , West Indonesia Island the Cactaceae family and is native to arid and and Vietnam. semiarid regions (MORTON, 1987) . Pitaya plants The pitaya fruit is high in soluble sugar (CHANG produce highly flavored edible and juicy fruits . and YEN ,1997). It has 19.5•‹ Brix in the core part The fruit is a many-black-seeded berry with a of the fruit and the predominant soluble sugars in thick wall or peel enclosing a delicately flavored the fruit are glucose and fructose (CHANG and and seedy pulp, with a pink , red or light yellow YEN, 1997). This phenomenon is the same as in color peel and the flesh is white or red in color . the prickly pear fruit (SAWAYA, et al., 1983, KUTI Pitaya fruit is a good source of minerals, glucose, and GALLOWAY, 1994). dietary fiber and vitamins (MORTON, 1987) ; and Acid and neutral invertase (ƒÀ-fructo-furanoside is eaten fresh or preserved in jams , syrups , or fructohydrolase E. C. 3. 2. 1. 26) are widely candies, and their juices can be used as the drink distributed in higher plants (BRADSHAW, et al., base with other beverage or used in flavorings and 1970 , RICHARDSON, et at., 1990). Increased food colorings ( PIMIENT-abarrios , 1994 ; invertased activity is usually associated with RODRIGUEU-Diaz, et al . , 1995) . Because pitaya increase hexose and decreased sucrose (PRESSEY can withstand prolonged drought (POPENOE,1974) and SHAW, 1966). Previous work with pitaya fruit and the fruit is easy to store at low temperature, (CHANG and YEN , 1997) has shown there are large it is considered to be a potential alternative crop differences on soluble solids among the core part, for their regions (CAMPOS-Hugueny , 1986) . stylar-end part , stem-end part and peripheral

Commercial production of pitaya fruit flourishes in part of the flesh. We were interested in 370 Food PeservationScience VOL. 24 NO, 6 1998 (18)

understanding what kinds of sugars were present accompainied by reduction of NADP +to

in those different parts and how they might be NADPH. The production of NADPH was metabolized . The objective of our study is to measured by a photometer at 340nm to calculate

determine suger content in the core part, stylar- the content of glucose. The fructose was first

end part, stem-end part and peripheral part of the converted to fructose-6- phosphate, then to

flesh and to demonstrate invertase and amylase glucose-6-phosphateby glucose isomerase. The

activity in the tissue of the above distinct following method was the same as in glucose

partsamong two distinct varieties of pitaya fruits. determination. Sucrose was first converted into

glucose and fructose by ƒÀ-fructosidase, and the Material and Methods following methods were as mentioned above.

1. Fruit samples 3. Assay for invertase and amylase

Fruits of var. Vietnam ( white flesh ) were Separated part of pitaya fruit flesh (10g) was

harvested from National Pingtung University of homogenized with a polytron in 1 me of

Science and Technology pitaya orchard , var. homogenization buffer containing 200mM HEPES

Hsian Lung (red flesh) were harvested from Mr. (pH7.8), 2mM EDTA, 1mM Mg-acetate and 200

CHEN' s orchard in Taichung. The fruit were hang- mM DTT. The extract was filtered through a 500

picked 50 days after flowering and the flesh were um nylon cheesecloth and centrifuged (18, 000g for

separated into the core part, stylar-end part, 30min at 0•`5•Ž) and then stored at-40(kutl,

steam-end part and peripheral part as shown in et al., 1994, BoNvEHI, etal., ｌ996), the

Fig. 1. The test points were the 1.5cm-diameter supernatant was dialyzed overnight . Aliquots of holes which were punched in the above parts, then the extract were subsequently used for invertase weighed, frozen and stored at -18°C . The flesh of and amylase assay. Acid invertase activity was the core part, stylar-end part, stem-end part and determined at pH 5.0 and neutral invertase activity

peripheral part (5g each) were homogenized at 7.0 ( HUBBARD, et al.,1991). Assays were

separately with 60me of 90% (V/V) ethanol and according to the procedure of Xu, et al.,(1989).

clarified by centrifugation . After standing for 2 Sucrose, 50mM was added to incubation buffers

wk at-12s•Ž, a 10mt aliquot of clear supernatant of (70mM K2HPO4/40mM citrate for acid invertase the homogenized samples was evaporated to and 160mM K2HP04 /20mM citrate for neutral

dryness under a stream of N2 and redissolved in 5 invertase) containing fruit tissue samples. The mi of deionized water and used for sugar analysis. reduction was allowed to proceed for 15 min at

2. Sugar analysis 25℃. The reaction was stopped by immersing

Glucose, fructose and sucrose were measured samples in boiling water for 10 min. Prior to

enzymatically using the methods of BERGMEYER , et boiling the acid invertase samples, 15me of 0.1M

al. (1974). Glucose was converted to glucose-6- NaOH was added to each sample to neutralize the

phosphate (G-6-P) and to gluconate-6-phoshate pH. The invertase acitivity was determind using methods of MOWLAHand ITOO (1982). Amylase assays were according to the procedure of MOWLAHand IToo (1982). Soluble starch, 1% was added to incubation buffer pH5.0 (70mM K2HPO 4/40mM citrate) containing fruit tissue samples. The reaction was allowed to process for 3 min at

30℃. Reactions were stopped by immersing the

sample in boiling water for 10 min. Prior to boiling the amylase samples, 15mt of 0.1M NaOH was Fig. 1 Core part, stylar-end part, stem-end part and peripheral part in pitaya flesh added to each sample to neutralize the pH. The (19) 〔Research Note〕 Sugars Distribution in Pitayas 371

amylase activity was determined using the content of sucrose was lower than glucose and methods of MOWLAH and IToo (1982). The fructose. In the var. Vietnam fruits, the sum of determination of protein concentration followed glucose, fructose and sucrose was varied in the method developed by BRADFORD (1976). different parts; as shown in Table 2, there were 174. 4mg/g, 144. lmg/g, 127. 9mg/g and 111.9 Results and Discussion mg/g in the core part, stylar-end part, stem-end The soluble solids in different parts of the flesh part and peripheral part, respectively. As were not the same. From Table 1, it is revealed compared to the data in Table1, these was a that the core part had the highest values in the positive relation between the soluble solid contents soluble solid contents, then the stylar-end part, and soluble sugars in the white-flesh pitaya. In stem-end part and the peripheral part had lowest the var. Hsian Lung fruits, as shown in Table 2, contents in soluble solid; there was the same there were 122.2mg/g, 107mg/g, 89mg/g and phenomenon in the two pitaya varieties of white 81mg/g in core part, stylar-end part, stem-end flesh and red flesh. Among the same part , the part and peripheral part respectively, this order pitaya variety with var. Vietnam had the higher was the same as in the white-flesh pitaya. soluble solid contents than that of the Hsian Lung As in a previous study (MORTON,1987), pitaya var. These two varieties were hand- picked 50 flesh contained more glucose than fructose and days after flowering, therefore the different the ratio varied in different parts of the fruit flesh physiology or growing speed among the varieties in this aspect, the two varieties of fruit could account for the differences should be , and mentioned had the same phenomenon. In the var. this result by advanced studies. CHANG and YEN Vietnam, as shown in Table 2, the ratio of

(1997) revealed that the core part of the white glucose to fructose, was 1.8, 1,6, 1.6 and 1.5 in flesh pitaya had the 19.5 + 1.6° Brix in souluble the stylar-end part, core part, peripheral part and solid; in this study, the core part only had the 18. stem-end part, respectively in the var. Hsian

0+ 1.6s•Ž Brix in souluble solid content, therefore, Lung, there were 1.4,1.37, 1.3 and 1. 2 in the there was a 1.5•Ž Brix less than the previous data . stylar- end part, core part, peripheral part and

This may be due to might be the variation of those stem-end part, respectively. Comparing these two white fruit flesh. varieties, the ratio of glucose to fructose is

Sucrose, glucose and fructose were the major different; there is a higher ratio of glucose to

soluble sugars in the flesh of pitaya fruit. The Table 2 Distribution of sugars in fruit flesh of two pitaya varieties Table 1 Distribution of soluble solids in fruit flesh of two pitaya varieties 372 Food PreservationScience VOL. 24 NO. 6 1998 (20) fructose in the var. Vietnam than in the Hsian total invertase activity. Maybe the var. Hsian Lung var., but there is the same phenomenon in Lung was more immature than the var. Vietnam both varieties that retio of glucose to fructose in pitaya picked at 50 days after flowering, so it was the stylar-end part had the higher value, then the more active in invertase activity. core part and the peripheral part, and the stem- Amylase activity was also found in these end part had the least value. In the pulp of prickly varieties of pitaya fruit examined (Table 4). The pear fruit, glucose and fructose were present in order of activity within each part was the same as almost equal amounts (1:1 ratio) (KuTI and the invertase was. The ratio of glucose to GLLowAY, 1994), so invertase is very important in fructose was over 1.2 (Table 2) in each part, and the glucose and fructose accumulation (TAKAHATA, the highest values of glucose to fructose were in et al., 1996); but in the pitaya flesh, the glucose the stylar-end part of the pitaya flesh . But the and fructose were not present in the same amylase activity of the stylar-end part was not the amount, so the amylase may play an important highest, therefore, this might be explained by the role in the pitaya flesh. ratio of invertase activity and amylase activity Acid invertase activity was found in the varieties between that of the stylar-end part to that of the of pitaya fruit examined (Table 3). However, the core part in pitaya flesh. From Table 3 and Table difference occurred in level of activity between 4, the ratio of the stylar-end part to the core part varieties as well as within each part. Hsian Lung in invertase activity are 0.85 and 0.85 in white fruits had the higher acid and total invertase flesh fruit and red flesh fruit, respectively; the activity compared with that of Vietnam fruits, but ratio of the stylar-end part to the core part in white-flesh fruits had the higher neutral invertase amylase activity are 0.89 and 0.91 in white flesh activity than that of red-flesh fruits except on the fruit and flesh fruit, respectively. The higher the peripheral part. In both varieties of pitaya fruits, amylase activity implied the larger amount of the the core part had the highest values in acid and glucose accumulation, so the ratio of glucose to total invertase activity, then the stylar-end part, fructose in the stylar-end part will be higher than the stem-end part and the peripheral part had the in the core part. The higher ratio of the glucose least values in those enzyme activities; the to fructose reveals that the hydrolysis of starch by neutral invertase activities was not in this order. amylase was executed in pitaya flesh, so amylase The var. Hsian Lung had higher activity than that plays a very important role in the accumlation of of the var. Vietnam both on acid invertase and hexose in pitaya fruit.

Table 3 Invertase activity in fruit flesh of two pitaya varieties

Table 4 Amylase activity in fruit flesh of two pitaya varieties (21) 〔ResearchNote〕 Sugars Distribution in Pitayas 373

(1991) Conclusions 8) KUTI, J . 0. and GALLOWAY, C . M . : Sugar In these two varieties , the ratio of glucose to composition and invertase activity in prickly fructose in the stylar-end part had higher value pear fruit, J . of Food Sci . , 59, 387-388, 393 then the core part and the peripheral part, and the (1994) stem-end part had the least value . The higher 9) MORTON, J . F . : Fruit of warm climates ratio of the glucose to fructose revealed that the (Miami, USA) , p, 505 (1987) hydrolysis of starch by amylase was executed in 10) MOWLAH, G . and ITOO, S . : Guava sugar the pitaya flesh , so amylase plays a very components and related enzymes at stages of important role in the accumulation of glucose in fruit development and ripening , Nippon pitaya fruit. Shokuhin Kokyo Gakkaishi , 29, 472 476 (1987) 11) PIMIENTA-BARRIOS , E. and NOBEL, P. S. : References Pitaya : An ancient and modern fruit crop of 1) BERGMEYER, H . U. , BERNT, E., SCHMID, F. Mexico, Economic Botany , 48 , 76-83 (1982) and STARK, H. Methods of Enzymatic Analysis, 12) POPENOE, W , : Manual of tropical and Vol . 3, BERGMEYER, H . U . , VERLAG Chemie, subtropical fruits (Hafner Press, New York) , WEINHEIM, ed . (Academic Press , Inc . , New p. 474 (1974) York and London) , pp. 1196-1201 (1974) 13) PRESSEY, R . and SHAW, R . : Effect of 2) BONBEHI, F . S . and ROSUA, N . S . temperature on invertase , invertase inhibitor , Enzymatic activities in the varieties of hazelnuts and sugar in potato tubers, Plant Physiol. , 41, (Corylus avellana L . ) grown in Tarragona , 1657-1661 (1966) Spain. Food Chemistry , 56 , 39-44 (1996) 14) RICHARDSON, D. L., DAVIES, H. V., Ross, 3) BRADSHAW, M . J . , CHAPMAN, J . M . and H. A. and MACKAY, G. R. : Invertase activity EDELMAN, J . : Enzyme formation in higher and its relation to hexose accumulation in potato plant tissue, A protein in inhibitor of invertase tubers, J . of Experimental Botany , 41, 95-99 synthesis of invertase synthesis affected by tissue (1990) slices of plant storage organ, Planta, 90, 323 15) RODORIGUES-DIAZ,A. J., OCAMPO-HRUTADO, ～332 (1970) A. L. and CASILLAS-GOMEZ, F. J. : Extraction 4 ) BRADFORD, M . M. : A rapid and sensitive of a natural colorant from peel of pitaya method for the quantification of microgram (Hylocereus undatus) fruit , Technologia de quantities of protein utilizing the principle of Alimentos , 30, 22-26 (1995) protein-dye binding, Analyt . Biochem . , 72, 248 16) SAWAYA, W . N . , KHAATCHADOURIAN, H . , ～254 (1976) SAFI, W. and MUHAMMED, H. M. : Chemical 5) CAMPOS- HUGUENY , L . , PERTZ, G . A . and characterization of prickly pear plup , Opuntia BARBEAU, G. : Developments in processing of ficus-indica and manufacturing of prickly pear pitaya ( Hylocereus undatus ) fruit , Boletin jam, J . Food Technol . , 18, 185-193 (1983) Tecnico LABAL . , 7, 37-45 (1986) 17) TAKAHATA, Y . , NODA, T . and SATO, T. : 6) CHANG, F. R. and YEN, C . R. : Flowering Relationship between acid invertase activity and and fruit growth of pitaya (Hylocereus undatus hexose content in sweet potato storage roots, J . Britt and Rose) , J . Chinese Soc . Hort . Soc . , 43, Agric . Food Chem . , 44, 2063-2066 (1996) 314-321 (1997) 18) Xu , D. P., SUNG, S . S. and BLACK, C . C . : 7) HUBBARD, N. L. PHARR, D. M. and HUBER, Sucrose metabolism in lima bean seeds , Plant S . C . : Sucrose phosphate synthase and other Physiol. , 89,421-425 (1989) sucrose metabolizing enzymes in fruits of various species, Physiol . Plant . , 82, 191-196 374 •@ Food Preservation Science VOL.24 NO.6 1998 (22)

の果実の可溶性固形物は17～19°Brixと高く,ミネラル, ピタヤ果実の部位による糖分の分布果糖,ブドウ糖,繊維およびビタミン類などが豊富に含呉明昌*・陳金樹** まれている。果肉の赤いものと白と赤の混合したものの * 屏東科技大学食品科学科二種類がある。二種類とも果実の各部分の可溶性固形物, (〒91207中華民国台湾省屏東県内浦郷学府路一号) 糖類および酵素活性がそれぞれ異なることが認められた。 ** フロリダ州立大学食品・農業研究科糖分の多い順にブドウ糖,果糖,ショ糖より構成されて (フロリダ州レイクアルフレッド) いたが,そのブドウ糖/果糖の比はインベルターゼとアピタヤ(Hylocereus undatus Britt. et. Rose)はサミラーゼの活性が関連しているように思われた。

ボテン属の果実で,熱帯や亜熱帯に栽培されている。そ (平成10年8月31日受理) 370 Food PeservationScience VOL. 24 NO, 6 1998 (18)

understanding what kinds of sugars were present accompainied by reduction of NADP+ to

in those different parts and how they might be NADPH . The production of NADPH was metabolized . The objective of our study is to measured by a photometer at 340nm to calculate

determine suger content in the core part, stylar- the content of glucose . The fructose was first

end part, stem-end part and peripheral part of the converted to fructose -6- phosphate , then to

flesh and to demonstrate invertase and amylase glucose -6-phosphate by glucose isomerase . The

activity in the tissue of the above distinct following method was the same as in glucose

partsamong two distinct varieties of pitaya fruits. determination . Sucrose was first converted into

glucose and fructose by ƒÀ-fructosidase , and the Material and Methods following methods were as mentioned above.

1. Fruit samples 3. Assay for invertase and amylase

Fruits of var. Vietnam ( white flesh ) were Separated part of pitaya fruit flesh (10g) was

harvested from National Pingtung University of homogenized with a polytron in 1 ml of

Science and Technology pitaya orchard , var. homogenization buffer containing 200mM HEPES

Hsian Lung (red flesh) were harvested from Mr. (pH7.8) , 2mM EDTA, 1mM Mg-acetate and 200

CHEN' s orchard in Taichung. The fruit were hang- mM DTT . The extract was filtered through a 500

picked 50 days after flowering and the flesh were um nylon cheesecloth and centrifuged (18,000g for

separated into the core part, stylar-end part, 30min at 0•`5•Ž) and then stored at -40•Ž (KUTI ,

steam-end part and peripheral part as shown in et al . , 1994 , BONVEHI , et al . , 1996) , the

Fig. 1. The test points were the 1.5cm-diameter supernatant was dialyzed overnight . Aliquots of

holes which were punched in the above parts, then the extract were subsequently used for invertase

weighed, frozen and stored at -18°C . The flesh of and amylase assay . Acid invertase activity was

the core part, stylar-end part, stem-end part and determined at pH 5.0 and neutral invertase activity

peripheral part (5g each) were homogenized at 7.0 (HUBBARD , et al . , 1991) . Assays were

separately with 60ml of 90% (V/V) ethanol and according to the procedure of Xu, et al . , (1989) .

clarified by centrifugation . After standing for 2 Sucrose, 50mM was added to incubation buffers

wk at-12•Ž, a 10ml aliquot of clear supernatant of (70mM K2HPO4/40mM citrate for acid invertase

the homogenized samples was evaporated to and 160 mM K 2 HPO 4 / 20 mM citrate for neutral

dryness under a stream of N2 and redissolved in 5 invertase) containing fruit tissue samples . The

ml of deionized water and used for sugar analysis. reduction was allowed to proceed for 15 min at

2. Sugar analysis 25 t . The reaction was stopped by immersing

Glucose, fructose and sucrose were measured samples in boiling water for 10 min . Prior to

enzymatically using the methods of BERGMEYER , et boiling the acid invertase samples, 15ml of 0.1M

al. (1974). Glucose was converted to glucose-6- NaOH was added to each sample to neutralize the

phosphate (G-6-P) and to gluconate-6-phoshate pH . The invertase acitivity was determind using

methods of MOWLAH and ITOO (1982) . Amylase

assays were according to the procedure of

MOWLAH and ITOO (1982) . Soluble starch, 1% was

added to incubation buffer pH5.0 (70mM K2HPO

4/40mM citrate) containing fruit tissue samples.

The reaction was allowed to process for 3 min at

30•Ž . Reactions were stopped by immersing the

sample in boiling water for 10 min. Prior to boiling

Fig. 1 Core part, stylar-end part, stem-end part and the amylase samples, 15ml of 0.1M NaOH was peripheral part in pitaya flesh added to each sample to neutralize the pH. The (19) 〔Research Note〕 Sugars Distribution in Pitayas 371

amylase activity was determined using the content of sucrose was lower than glucose and methods of MOWLAH and IToo (1982). The fructose. In the var. Vietnam fruits, the sum of determination of protein concentration followed glucose, fructose and sucrose was varied in the method developed by BRADFORD (1976). different parts; as shown in Table 2, there were 174. 4mg/g, 144. lmg/g, 127. 9mg/g and 111.9 Results and Discussion mg/g in the core part, stylar-end part, stem-end The soluble solids in different parts of the flesh part and peripheral part, respectively. As were not the same. From Table 1, it is revealed compared to the data in Table 1, these was a that the core part had the highest values in the positive relation between the soluble solid contents soluble solid contents, then the stylar-end part, and soluble sugars in the white-flesh pitaya. In stem-end part and the peripheral part had lowest the var. Hsian Lung fruits, as shown in Table 2, contents in soluble solid; there was the same there were 122.2mg/g, 107mg/g, 89mg/g and phenomenon in the two pitaya varieties of white 81mg/g in core part, stylar-end part, stem-end flesh and red flesh. Among the same part , the part and peripheral part respectively, this order pitaya variety with var. Vietnam had the higher was the same as in the white-flesh pitaya. soluble solid contents than that of the Hsian Lung As in a previous study (MORTON,1987), pitaya var. These two varieties were hand- picked 50 flesh contained more glucose than fructose and days after flowering, therefore the different the ratio varied in different parts of the fruit flesh physiology or growing speed among the varieties in this aspect, the two varieties of fruit could account for the differences should be , and mentioned had the same phenomenon. In the var. this result by advanced studies. CHANG and YEN Vietnam, as shown in Table 2, the ratio of

(1997) revealed that the core part of the white glucose to fructose, was 1.8, 1,6, 1.6 and 1.5 in flesh pitaya had the 19.5 + 1.6•‹ Brix in souluble the stylar-end part, core part, peripheral part and solid; in this study, the core part only had the 18. stem-end part, respectively in the var. Hsian

0+ 1.6s•‹ Brix in souluble solid content, therefore, Lung, there were 1.4,1.37, 1.3 and 1. 2 in the there was a 1.5•‹ Brix less than the previous data . stylar- end part, core part, peripheral part and

This may be due to might be the variation of those stem-end part, respectively. Comparing these two white fruit flesh. varieties, the ratio of glucose to fructose is

Sucrose, glucose and fructose were the major different; there is a higher ratio of glucose to

Table 3 Invertase activity in fruit flesh of two pitaya varieties

Table 4 Amylase activity in fruit flesh of two pitaya varieties (21) 〔ResearchNote〕 Sugars Distribution in Pitayas 373

(1991) Conclusions 8) KUTI , J . 0. and GALLOWAY , C . M . : Sugar

In these two varieties , the ratio of glucose to composition and invertase activity in prickly fructose in the stylar-end part had higher value pear fruit, J . of Food Sci . , 59, 387-388, 393 then the core part and the peripheral part, and the (1994) stem-end part had the least value . The higher 9) MORTON , J . F . : Fruit of warm climates ratio of the glucose to fructose revealed that the (Miami, USA) , p, 505 (1987) hydrolysis of starch by amylase was executed in 10) MOWLAH , G . and ITOO , S . : Guava sugar the pitaya flesh , so amylase plays a very components and related enzymes at stages of important role in the accumulation of glucose in fruit development and ripening , Nippon pitaya fruit. Shokuhin Kokyo Gakkaishi , 29, 472 476 (1987)

11) PIMIENTA- BARRIOS , E. and NOBEL , P. S. :

References Pitaya : An ancient and modern fruit crop of

1) BERGMEYER , H . U. , BERNT , E., SCHMID , F. Mexico, Economic Botany , 48 , 76•`83 (1982)

and STARK , H. Methods of Enzymatic Analysis, 12) POPENOE , W , : Manual of tropical and

Vol . 3, BERGMEYER , H . U . , VERLAG Chemie, subtropical fruits (Hafner Press, New York) ,

WEINHEIM , ed . (Academic Press , Inc . , New p. 474 (1974)

York and London) , pp. 1196•`1201 (1974) 13) PRESSEY , R . and SHAW , R . : Effect of

2) BONBEHI , F . S . and ROSUA , N . S . temperature on invertase , invertase inhibitor ,

Enzymatic activities in the varieties of hazelnuts and sugar in potato tubers, Plant Physiol. , 41,

(Corylus avellana L . ) grown in Tarragona , 1657•`1661 (1966)

Spain. Food Chemistry , 56 , 39•`44 (1996) 14) RICHARDSON , D. L., DAVIES , H. V., Ross,

3) BRADSHAW , M . J . , CHAPMAN , J . M . and H. A. and MACKAY , G. R. : Invertase activity

EDELMAN , J . : Enzyme formation in higher and its relation to hexose accumulation in potato

plant tissue, A protein in inhibitor of invertase tubers, J . of Experimental Botany , 41, 95-99

synthesis of invertase synthesis affected by tissue (1990)

slices of plant storage organ, Planta, 90, 323 15) RODORIGUES-DIAZ, A. J., OCAMPO-HRUTADO , ～332 (1970) A. L. and CASILLAS-GOMEZ , F. J. : Extraction

4 ) BRADFORD, M . M. : A rapid and sensitive of a natural colorant from peel of pitaya

method for the quantification of microgram (Hylocereus undatus) fruit , Technologia de quantities of protein utilizing the principle of Alimentos , 30, 22•`26 (1995) protein-dye binding, Analyt . Biochem . , 72, 248 16) SAWAYA , W . N . , KHAATCHADOURIAN , H . , ～254 (1976) SAFI , W. and MUHAMMED , H. M. : Chemical

5) CAMPOS - HUGUENY , L . , PERTZ , G . A . and characterization of prickly pear plup , Opuntia

BARBEAU , G. : Developments in processing of ficus-indica and manufacturing of prickly pear

pitaya ( Hylocereus undatus ) fruit , Boletin jam, J . Food Technol . , 18, 18•`193 (1983)

Tecnico LABAL . , 7 , 37•`45 (1986) 17) TAKAHATA , Y . , NODA , T . and SATO , T. :

6) CHANG , F. R. and YEN , C . R. : Flowering Relationship between acid invertase activity and

and fruit growth of pitaya (Hylocereus undatus hexose content in sweet potato storage roots, J .

Britt and Rose) , J . Chinese Soc . Hort . Soc . , 43, Agric . Food Chem . , 44, 2063•`2066 (1996)

314•`321 (1997) 18) Xu , D. P., SUNG , S . S. and BLACK , C . C . :

7) HUBBARD , N. L. PHARR , D. M. and HUBER , Sucrose metabolism in lima bean seeds , Plant

S . C . : Sucrose phosphate synthase and other Physiol. , 89,421•`425 (1989)

sucrose metabolizing enzymes in fruits of

various species, Physiol . Plant . , 82, 191-196 374 Food Preservation Science VOL.24 NO.6 1998 (22)

ボテン属の果実で,熱帯や亜熱帯に栽培されている。そ (平成10年8月31日受理)