(23) Food Preservation Science VOL.23 NO.6 1997 [Article] 315

Effects of Coating Treatment with Sucrose Fatty Acid Esters on the Ripening of Cavendish Banana.

MOMEN Mir Nurul*, TATSUMI Yasuo ** and SHIMOKAWA Keishi**.

* The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 kourimoto Kagoshima Shi 890, Japan. **Faculty of Agriculture, Miyazaki University, 1-1 Gakuenkibanadai-nishi, Miyazaki Shi 889-21, Japan.

Effects of coating with three different kinds of sucrose fatty acid esters-namely, sucrose lauric

acid esters (SLE) , sucrose palmitic esters (SPE) , and sucrose stearic acid esters (SSE) , were

studied on the ripening of Cavendish bananas. The bananas were coated with 0.5% sucrose fatty

acid esters solution and stored at 20•Ž . The use of sucrose fatty acid ester coating delayed banana

ripening. The onset of ripening was first observed in non-coated bananas, then subsequent in SE,

SLE and SPE-coated bananas. Initiation of respiratory climacteric and ethylene production was

delayed by sucrose fatty acid esters coating. The longest storage period of bananas was 52 days

which was coated with SPE and found to be statistically significant. The total and the reducing

sugar of SLE-coated bananas were observed to be higher. A scanning electron microscopy study

showed that the stomatal apertures of bananas were partially blocked by fragments of the

coating treatment, which might form a physical barrier of gaseous diffusion with the external

atmosphere.

(Received Jan. 20, 1997)

The sucrose esters of fatty acids were developed was significantly reduced, while the elevation of as emulsifiers 1). However, it has also been internal carbon dioxide was not statistically established that the shelf life of fruit may be significant. In 1982, the US Food and Drug extended by coating the peel with sucrose esters2). Administration (FDA) approved the use of sucrose In research on Granny Smith apples, TROUT3) fatty acid esters as a protective coating to retard showed that coating treatment increased the ripening and spoilage of apples, bananas and

resistance of the skin to gaseous diffusion, greatly pears6).

reducing the internal oxygen concentration and Quality long - term maintenance of perishable the respiratory rate, and retarding ripening fruits is a major consideration in a modern fresh changes. The most spectacular effect in ripening fruit market. As sucrose fatty acid esters are edible was a marked retardation of normal yellowing of and are safe materials, they are available for the skin, which is mainly controlled by the internal coating materials. Considerable research has been oxygen supply. BANKS4),5)studied the effect of done regarding the use of different coating coating treatment with TAL Pro-long (a mixture materials for quality maintenance and long time -

of sucrose esters and sodium carboxymethyl- preservation of different perishable fruits, cellulose) on the internal gas concentration of including bananas5),7)•`10). Very little information is green and pre-climacteric banana fruit, and found available on the effects of specific types of sucrose that the internal oxygen content of coated fruit fatty acid esters on the ripening of the Cavendish 316 Food Preservation Science VOL.23 NO.6 1997 (24) banana. MURATA11)showed that chilling injury of Table1 Descriptions of the different ripening stages citrus fruits under cold storage and cold treatment of banana especially in physical appearance and is effectively reduced by treatment with different color change. sucrose fatty acid esters of different HLB (hydrophilic - lipophilic balance ) values and different fatty acid compositions. In this study, three commercial sucrose fatty acid esters with the same HLB value but different saturated fatty acid (C12:0to C18:0) esters, i. e., sucrose lauric acid eaters (SLE), sucrose palmitic acid esters (SPE) , and sucrose stearic acid esters

(SSE) , were tested as coating agents to identify room temperature. The samples were stored at their effects on the respiration rate and ethylene 20•Ž and 80%•`85% relative humidity. production of the Cavendish banana during Stages of Ripening ripening at 20 r . The effects of these coating In the present study, the effect of coating treatments on the storage period, reduction and treatment with each type of sucrose fatty acid total sugar content and on the stomatal aperture of esters was examined during the whole storage

Cavendish bananas were also studied. period of banana fruits at different stages. The Materials and Methods characteristics of different stages are described in Table 1.

Materials Measurement of Carbon Dioxide and Ethylene

Pre-climacteric Cavendish bananas (Musa AAA The bananas were placed into a 10 liter plastic group, Cavendish subgroup) imported from the jar, then the jar was tightened properly and the

Philippines were purchased from the Miyazaki bananas were incubated for an hour. After banana warehouse. Mature green bananas with incubation, one ml of the head space gas was uniform size, shape and color were carefully carefully taken from the plastic jar through selected. Five fingers were taken together from a a silicon rubber stopper. Carbon dioxide banana hand for each replication. The cut ends concentration was measured on a Shimadzu GC-6 were smeared with vaseline to minimize gas chromatograph equipped with a thermal dehydration and fungal infection. The emulsifiers conductivity detector and a Porapak R column (0 were used without further purification . Sucrose 3 mm•~2 m) . Ethylene was measured on a eaters of fatty acids (Ryoto Sugar Ester L-1695, P Shimadzu GC-7 gas chromatograph equipped with -1670 and S-1670) used were commercial samples a hydrogen flame ionization detector and an from Mitsubishi - Kagaku Corporation. The active alumina column (ƒ³3mm•~2m ) . purities of fatty acids esterified with sucrose were Scanning Electron Microscopy

approximately 95 % lauric acid ( C 12: 0 80 % For the scanning electron microscopy (SEM) palmitic acid (C16:0)and 80% stearic acid (C18:0) observation, 1•~1•~0.5 cm sections of banana peel

for SLE, SPE and SSE, respectively. The three tissue were sampled by using a sharp knife and sucrose fatty acid esters had an HLB of were preserved at -70•Ž. The samples were

approximately 16. The total contents of the prepared by a freeze drying method for microscopy monoester of SLE, SPE and SSE were 75%, 80% observation. The samples were sputtered with

and 80%, respectively. platinum/palladium and observed with a Hitachi

Coating treatment and storage S-4100 scanning electron microscope, operated at

Bananas were dipped into 0.5 % sucrose fatty 15 kV. acid esters solutions for 5 minutes and dried at (25) 〔Article〕Effect of Sucrose Ester on the Banana Ripening 317

Weight Loss

Bananas from each coating treatment were weighed individually during the storage period and the percentage of weight loss was calculated.

Reducing and Total Sugar

Three gm. of banana pulp was taken from the middle part of a banana finger and macerated with a mortar and pestle with 20 me of distilled water.

The homogenates were centrifugated at 10,000xg for 10 minutes, and the supernatant was stored at -20•Ž until use . The samples were diluted properly

and the reducing sugar content was measured by Fig. 1 Effect of coating treatment with three differ- spectrophotometry at 660 nm by the Somogyi - ent kinds of 0.5% sucrose fatty acid ester on the Nelson method12). For the measrurement of total ripening stages of cavendish banana during storage sugar content, 2 me of 2 M sulfuric acid was added at 20 t . to a 2 me sample and kept boiling for 15 minutes

for sugar hydrolysis. The solution was cooled and

2.5 me of 2 M sodium hydroxide was added for

neutralization. The solution was filled up to 10 me

with 3.5 me of water. One mil of properly diluted

hydrolyzed solution was used for the total sugar

measurement by spectrophotometry at 660 nm

using the Somogyi-Nelson methoe.

Statistical Analysis

The experiment was conducted according to a

completely randomized design13). The significance

of the difference between pairs of means was Fig. 2 Effect of coating treatment with three different evaluated by a least sifnificant difference test'3). kinds of 0.5% sucrose fatty acid ester on the respi- Results ration of cavendish banana during storage at 20t.

The effects of coating treatment with three

different kinds of 0.5% sucrose fatty acid esters on

the ripening of bananas were investigated at 20t .

The use of SPE coating significantly delayed

banana ripening compared to of other coatings at

stage-4, stage-5 and stage-7. The onset of ripening

was first observed in non-coated bananas in 26

days, then subsequently ripening was observed in

the SSE-coated sample in 30 days, the SLE-coated

bananas in 32 days and the SPE-coated bananas

in 36 days in storage (Fig. 1). The sample coated

with SPE had the longest storage period of 52 days, Fig. 3 Effect of coating treatment with three different while the non - coated sample had the shortest kinds of 0.5% sucrose fatty acid ester on the ethyl- storage period of 46 days. ene production of cavendish banana during storage

The bananas coated with sucrose fatty acid at 20 t . 318 Food Preservation Science VOL. 23 NO. 6 1997 ( 26 ) esters exhibited climacteric types of respiration with SPE had delayed initiation of respiration and (Fig. 2) and ethylene production (Fig. 3) . The ethylene production compared to others and onset of climacteric respiration took place first for resulted in a longer storage period. The initiation non-coated bananas in 26 days, then for bananas of respiration and ethylene production of bananas coated with SSE in 28 days, the sample coated with was delayed 6 days and 8 days respectively by the SLE in 30 days, and finally the bananas coated coating treatment with SPE compared with the with SPE in 32 days in the storage period. The control. The bananas with all treatments were ethylene production coincided with the rise of found to start ripening soon after ethylene respiration for all treatments and the initiation of production and also after an increase in ethylene production was found to be 26 days for respiration. non - coated bananas, 28 days for SSE - coated The morphological study of the banana peel bananas, 32 days for SLE-coated samples, and 34 being after coated with 0.5% sucrose fatty acid days for SPE - coated bananas bananas coated esters was examined with SEM. The stomatal

Plate 1 Scanning electron microscopic stomatal views of banana peel surface. A. Without coating treatment; B. With SLE coating treatment; C. With SPE coating treatment; D. With SSE coating treatment; (27) [Article] Effect of Sucrose Ester on the Banana Ripening 319

aperture was clearly found on a peel of non-coated bananas (Plate 1-A) . The surface peel of bananas coated with sucrose fatty acid esters was rough and unclear, and stomatal apertures were partially blocked with small fragments of SLE, SPE and SSE (Plate 1-B, C & D).The stomatal apertures of the SPE-coated bananas were more signficantly blocked with the small fragments than the other samples. Coating layers of sucrose fatty acid esters on glass ( cover glass for microscope ) were observed with SEM. The small fragments of sucrose fatty acid esters were observed within their coating layers (Plate 2-A, B & C), which

A. Coating with SLE were similar to the small fragments found inside the stomatal apertures of bananas coated with the sucrose fatty acid esters. Many small fragments were found in SPE coating compared to SLE and SSE coating. The effects of coating with sucrose fatty acid esters on the weight loss of bananas are shown in Fig. 4. The weight loss of SPE-coated bananas decreased compared to the others during the entire storage period. The weight loss of the SSE-coated sample was almost the same as the control during storage. Furthermore, the weight loss of SLE - coated bananas did not deviate signficantly from

B. Coating with SPE the control. The sugar contents were analyzed at stage-4, stage-5 and stage-7 of the ripening bananas. A distinct increase in the total and the reducing sugar

C. Coating with SSE

Plate 2 Scanning electron microscopic views of

cover glasses coated with sucrose fatty acid esters. Fig. 4 Effect of coating treatment with three different

kinds of 0.5% sucrose fatty acid ester on the weight

loss of cavendish banana during storage at 20•Ž. 320 Food Preservation Science VOL.23 NO.6 1997 (28)

Table 2 The total and the reducing sugar content (g/ (C16:0), stearate (C18:0), and oleate (C18:1), had 100g) of cavendish bananas coated with three dif- different effects on the pitting index and on the ferent kinds of sucrose faffy acid ester during stor- chilling injury of kabosu, seminole, lemon and age at 20•Ž. grapefruits during and after cold treatment. Among the three cucrose fatty acid esters coating treatments, SPE coating treatment was more effective in delaying the initiation of respiration, ethylene production and ripening of bananas. SPE coating treatment produced uniform coating on the banana surface and formed more stomatal blockage by tiny fragments, which might effecively have depressed the internal oxygen content of bananas, and which resulted in a longer storage LSD, least significant difference. period. SEM observation also showed that the SPE coating treatment produced uniform coating and contents was observed at stage-7. The total sugar tiny fragments on cover glass. BANKs4) reported content of bananas coated with SLE at stage-7 that bananas coated with TAL Pro - long ( a was 20.9g/100g (Table 2) , which was found to be mixture of sucrose esters and sodium higher compared with others, and was statistically carboxymethylcellulose ) modified their internal significant. On the other hand, the reducing sugar atmospheres by reducing the internal oxygen content of bananas coated with SLE was 4.6g/100 content without increase in the level of carbon g, which was found to be higher compared with dioxide, which depressed the rate of respiration others but was not statistically significant. The and delayed degreening. lower quantities of the total and the reducing sugar Fruits and vegetables are very vulnerable to contents were 7.5 g / 100 g and 2.5 g / 100 g, water loss through respiration once they are respectively, which were found in the sample harvested and coating affects water vapor loss14). coated with SSE at stage-4. The sensory test panel The sucrose fatty acid esters coating treatment assessed that the use of these three kinds of might supperss transpiration from the banana sucrose fatty acid esters did not hamper the taste surface and reduce water loss. MOMEN15) also of the bananas, but the sample coated with SLE observed that the wax emulsion coating on the had a good taste (data not shown) . surface of bananas, both `Sabri' and `Amritasagar' varieties, delayed ripening and reduced weight Discussion loss. The weight loss percent was less in SPE- The three different kinds of sucrose fatty acid coated bananas than those of SLE and SSE coating esters used as coating agents in this study delayed treatments, suggesting that SPE coating initiation of respiration and ethylene production treatment effectively suppressed transpiration of Cavendish bananas, which ultimately delayed from the banana surface by covering better than ripening. Although these sucrose fatty acid esters SLE or SSE coating treatments. The total sugar had the same HLB value and saturated fatty acids content of the SLE-coated banana was higher than residues, their effects were different on the other treatments of stage-7. The reason for the ripening of bananas. This different effect might be higher sugar content in bananas coated with SLE attributed to the difference in composition of fatty is not clear. acids esterified with sucrose. MURATA11)showed In this study, the use of sucrose fatty acid esters that different types of sucrose fatty acid esters, produced a partial blockage of the stomatal i. e. laurate (C12:0, myristate (C14:0), palmitate spertures of bananas, which supported the (29) 〔Article〕 Effect of Sucrose Ester on the Banana Ripening 321 contention that coating bananas with TAL Pro- Am. Oil Chem. Soc., 60, 862 (1983) . long has been shown to form a physical barrier to 2) KESTER, J. J. and FENNEMA, 0. R. : Food gaseous diffusion through the stomata on the fruit Technol., 12, 47 (1986) . surface, the principal route for gaseous exchange 3) TROUT, S. A., HALL, E. G. and SYKES, S. M. of the fruit tissues with the external atmosphere16). : Austral. J. Agric. Res., 4, 57 (1953). The sucrose fatty acid esters coating treatment 4) BANKS, N. H. : J. Exp. Bot., 34, 871 (1983) . delayed initiation of respiration and ethlene 5) BANKS, N. H. : J. Exp. Bot., 35, 127(1984a). production and might produce a semi-permeable 6) RANDOLPH,W. F.: Fed. Reg., 47, 55475(1982). modified atmosphere within banana fruits which 7) MELLENTHIN, W. M., CHEN, P. M. and results in a delay in ripening. LOWINGSand CUTTS17) BORGIC,D. M. : Hort Science, 17, 215 (1982) . reported that an edible coating mixture composed 8) KESTER, J. J. and FENNEMA, 0. R. : Food of sucrose fatty acid esters, sodium Technol., 42, 47 (1988) . carboxymethylcellulose, and mono and 9) DRAKE, S. R., FELLMAN,J. K. and NELSON, J. diglycerides would produce a semi - permeable W. : J. Food Sci., 52, 1283(1987). modified atmposphere within fresh fruit after 10) SMITH, S. M. and STOW, J. R. : Ann. Appl. application. HESSELMAN and FREEBAIRN18) also Biol., 104, 383 (1984) . reported that modified atmosphere at low oxygen 11) MURATA, T. : Acta Hort., 269, 205(1990). concentration reduced ethylene production ability 12) FUKUI, S. Seibtsu Kagaku Jikken Hou 7, of banana fruits, which resulted in the delay of Kangen Tou no Teiryou Hou, Gakukai Shupan banana ripening. Center, p. 10 (1969) . The sucrose fatty scid esters are easy to handle 13) GOMEZ,K. A. and GOMEZ,A. A. : Statistical and safe to eat, so their suitable concentration, Procedure for Agricultural Research. John type and method of treatment should be identified Wiley & Sons Inc., New York, (1976) . to use as coating materials for long term 14) NUSSINOVITCH,A. and LURIE, S. Postharvest preservation of perishable fruits, such as the News Infor., 6, 53 (1995) . banana. The esters coating treatment reduces 15) MOMEN, M. N., RAHIM, M. A., FAROOQUE,A. respiration, ethylene production and delay of M. and CHOUDHURY, M. S. H. : Progress. banana ripening, which may improve storage Agric., 4, 41 (1993) . quality and produce economic benefit. The 16) BANKS, N. H. : Scientia Hort., 24, 279 (1984b) . treatment partially blocks the stomatal apertures 17) LOWINGS,P. H. and CUTTS, D. F.: Proc. Inst. of banana fruit and may change the level of Food Sci. Technol., 15, 52 (1982). internal gases. Therefore, further study should be 18) HESSELMAN,C. W. and FREEBAIRN,H. T. : J. done to determine the effect sucrose fatty acid Amer. Soc. Hort. Sci., 96, 635 (1969) . ester coating on the internal gas phases of bananas and on the physiology of ripening. バ ナ ナ の 成 熟 に 対 す る シ ョ糖 脂 肪 酸 エ ス テ ル Acknowledgements 被 覆 処 理 の 影 響 に つ い て We are grateful to the Japanese Government, Ministry of Education (Monbusho) , funding this モ ー メ ン ミル ヌ ル ル*・ 辰 巳保 夫**・ 下 川 敬 之** study was materialized. We are also grateful to * 鹿 児 島大 学 連 合 農 学研 究 科 Mitsubishi Kagaku Foods Corporation for (〒890鹿 児 島市 郡 元1-21-24) providing the sucrose fatty acid esters. ** 宮崎 大 学 農 学部 (〒889-21宮 崎 市学 園木 花 台西1-1) Literature Cited 1) GUPTA, R. K., JAMES, K. and SMITH, F. J.: J. シ ョ糖 ラ ウ リル 酸 エ ス テ ル(SLE),シ ョ糖 パ ル ミチ 322 Food Preservation Science VOL.23 NO.6 1997 (30)

ン酸 エ ス テ ル(SPE),シ ョ糖 ス テ ア リン 酸 エ ス テ ル た。 特 に シ ョ糖 パ ル ミチ ン酸 エ ス テル 処 理 は成 熟 の遅 延 (SSE)の3種 類 の シ ョ糖 脂 肪 酸 エ ス テ ル 被 覆 が キ ャ 効 果 が 大 き く,成 熟段 階7(ス ター)に 達 す る の に52 ベ ンデ ィ ッ シ ュバ ナ ナ の 成 熟 に 対 す る影響 を検 討 した 。 日間 を要 した。 全 糖 及 び還 元 糖 含量 は シ ョ糖 ラ ウ リル酸 バ ナ ナ は0 .5%の シ ョ糖 脂 肪 酸 エ ス テ ル 水 溶 液 で 被 覆 処 エ ス テ ル処 理 区 で高 か っ た。 走 査 型 電 子 顕 微 鏡 で観 察 す 理 して20℃ に貯 蔵 した 。 成 熟 の 開 始 は 無 処 理 区 が 最 初 る とシ ョ糖 脂 肪 酸 エ ス テ ル処 理 区 のバ ナ ナ 果 皮 の気 孔 の で,そ の 後 シ ョ糖 ス テア リン酸 エ ス テル 処 理 区,シ ョ糖 中 に粒 子 が見 られ た。 シ ョ糖 脂 肪 酸 エ ス テ ル に 由来 す る ラ ウ リル 酸 エ ス テル 処 理 区 そ して シ ョ糖 パ ル ミチ ン酸 エ 粒 子 が気 孔 に 詰 ま るこ とが 外 気 との ガ ス交 歓 の 障壁 と ス テル 処 理 区 の順 に な っ た。 ク ラ イマ ク テ リッ ク呼 吸 の な っ て バ ナ ナ の成 熟 を遅 らせ る と考 え た。 発 現 や エ チ レ ン生 成 が シ ョ糖 脂 肪 酸 エ ス テル 処 理 で遅 れ (平成9年1月20日 受 理)