Physicochemical and nutritional properties of peels, pulp and arils of gac (Momordica cochinchinensis) fruits grown in Malaysia Mohd Nazri AR1,2, Amin I2, Mohd Desa H3 1Faculty of Food Science and Nutrition, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia 2Department of Nutrition and Dietetic, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia 3International Tropical Fruits Network (TFNet), Box 334, UPM Post Office, 43400 Serdang, Selangor, Malaysia *Email:
[email protected] INTRODUCTION
The pulp in the study was 39% of fruit weight and it was significantly lower compare to findings by Kha (2000) as 49% of fruit weight and Parks et al. (2013) that accounts for between 52 and 75% of the total fruit by weight (Parks et al. 2013).
Momordica cochinchinensis Spreng or Gac is classified in the melon family (Cucurbitaceae) (Dujardin & Kitthawee, 2013) which includes cucumbers, squash, luffa and bitter melon (Parks et al. 2013) and considered as an indigenous tropical plant to Southeast Asia. It was grown in many countries in tropical regions such as Thailand, Vietnam, Laos and China (Kubola et al., 2013).
The arils of the study contribute 19% of fresh weight, and significantly lower compare to Tran et al. (2008), that stated that the fruit flesh contains red soft and sticky arils, 1–3 mm thick, covering black seeds, accounting for 25% of the fruit weight. This finding was in the range (19%) as reported by Parks et al. (2013) around 6 – 31% per fruit weight. The aril component of gac has been reported elsewhere as 10, 18 and 24.6% of fruit weight (Ishida et al., 2004; Nhung et al., 2010; Kha, 2010).
It was called by different name such as spiny gourd, spinny bitter gourd, cochinchin gourd, sweet gourd (English name), Momordica cochinchinensis Spreng, Muricia cochinchinensis Lour., and Muricia mixta Roxb. (Latin names), Fak kao (in Thailand), Gac (in Vietnam), Mak kao (in Laos), Moc Niet Tu (in China) and Bhat kerala (in India) (Kubola & Siriamornpun, 2011; Kubola et al., 2013), Kushika and Mokubetsushi (among Japanese), Hakur, Kakrol and Kakor (Hindustan), and Teruah (Malaysia). Gac fruit comparatively contains high concentrations of vitamin E (7.6 mg/100 g), unsaturated (70%) and polyunsaturated (50%) fatty acids (852 mg/100 g of edible portion) or 102 mg per g of edible portion (Kha et al., 2013). Fats content in gac pulp plays an important role in the absorption of carotenes, vitamin E and other fat-soluble nutrients (Kha et al., 2010; Kha, et al., 2013).
The seeds were found to contribute 23% of fresh weight. The seed size was 20.33mm±0.58 in length and it never been reported. Vuong (2000) reported that, each fruit has on average between 15 to 20 round, compressed and sculptured seeds, meanwhile Parks et al. (2013) stated that the seed is about 30-40 per fruit, and represent for 18 to 30% of fruit weight.
Gac aril contains highly valuable source of carotenoids, especially βcarotene (more than 16 mg/100 g) or 101 µg/g (Kha et al., 2013) and lycopene (more than 50 mg/100 g) or 380 µg/g (Kha et al., 2013), mainly in the red aril (Kha et al., 2010). β-carotene in the gac aril is also 10 times more concentrated than in carrots (Mai et al., 2013).
The skin colour (L*, a*, b*) of the gac fruit were 40.69±0.82, 43.93±0.59 and 37.38±1.67 respectively. The colour index showing that pulp had lighter compared to arils, and arils colour had more red compared to the pulp.
Therefore, this study was to examine the physicochemical and nutritional properties of peels, pulp and arils of gac (Momordica cochinchinensis) fruits as it is first grown in Malaysia. METHODOLOGY
The mature-ripe fruit (yellow to red skin) was harvested and transported to laboratory and cleaned under tap water. The physical measurements (weight, length and circumference) were determined using analytical weigh balance, Mitutoyo stainles steel caliper, 0 – 6 inch (Made in Japan), and flexible measuring tape. Fruit color (skin, pulp and arils) has been measured using Ultrascan PRO USP1092, HunterLab, D65/10 (USA). Total soluble solids (TSS) has been determined using Hand Refractometer, Atago N1 (Brix 0 – 32%) (Japan). The peel, pulp (endocarp), arils (mesocarp) and seeds were separated and stored at -80°C prior to freeze dried (lyophilization) (Christ Beta 2-8 LD plus, GmbH, Germany). The sample particle size has been reduced using Waring stainless steel commercial blender. The nutritional properties (proximate composition) of peels, pulp and arils were performed according to AOAC method.
For the nutritional properties of gac fruit grown in Malaysia, we compared the findings to the results as published by Vuong (2000) and Gunasekaran et al. (2014).
RESULTS AND DISCUSSION
The fruit weight in the study was 245g (oblong shape) to 762g (round shape) with the length to circumference ratio was 1 to 2.4cm. As reported by Vuong (2000), there are two types of gac fruit: the oblong fruit weighs between 500g and 1600g with oblong type is 6-10cm in length and can be 13 cm long, and round is 4-6 cm in length. In addition, Shadeque and Baruah (1984) reported that in Assam, India the gac fruit weighs from 1 to 3 kg. This finding shows that the gac fruit grown in Malaysia was smaller size compared to In Vietnam and India. Fresh weight (g)
Length (cm)
Circumference (cm)
451.14±171.87
12.0±1.78
29.04±3.24
Length: Circumference ratio 1 : 2.4
There is 19% of fruit weight for the peel in the study. This finding was not significantly different compared to the result by Parks et al. (2013) that, the skin (about 17% of fruit weight). The fruit flesh thickness in study was 21.25mm±4.86, and it was reported as one-half-inch thick (Vuong, 2000). Percentage to fresh Colour Fruit part fruit weight L* a* b* (mean±SD) Peel 19±0.02 40.69±0.82 43.93±0.59 37.38±1.67
pH
NA
Pulp
39±0.02
42.20±1.99 24.68±1.49 43.76±4.33 5.65±0.02
Arils
19±0.01
26.62±1.10 36.35±1.24 27.62±2.63 5.54±0.02
Seeds
23±0.02
NA
NA
NA
NA
The pH for the edible parts (pulp and arils) of the gac fruit were 5.65±0.02 and 5.54±0.02 with 0.01 to 0.02g/L and 0.03 to 0.05g/L of titratable acidity (TA) respectively. In addition, the arils contained higher TSS compared to pulp with 11.57%±0.52 and 4.90%±0.33 °Brix.
Titratable acidity (g/L)
Total soluble solids
NA 0.01 0.02 0.03 0.05 NA
NA 4.90±0.33 11.57±0.52 NA
Fruit part
Moisture content (%)
Peel Pulp Arils
88.10±0.25 94.94±0.26 90.67±0.12
Crude Total available Crude fat Total Protein Ash content carbohydrate content (%) dietary fibre content (%) (%) (%) (%) 13.99±0.11 19.29 0.96±0.07 6.16±0.26 68.56 17.29±0.71 30.93 0.69±0.13 4.57±0.22 43.53 55.62 14.55%±0.27 5.76±0.32 20.55 6.31±0.55
Pulp had significantly highest the moisture content (94.94%±0.26), compared to arils (90.67%±0.12) and peels (88.10%±0.25). Gunasekaran et al. (2014) reported that the moisture is 88.6%, meanwhile Vuong (2000) reported that the moisture content of the fruit was 90.2% and 77% for the arils which is significantly lower compared to the study. Gac fruit was found to have high ash content particularly in pulp at the range of 17.29 to 23.45 followed by peels (13.99 to 15.91) and arils (6.31 to 13.12). Vuong (2000) reported that there is 0.7 mg of ash from gac arils. The gac fruit in study was also found to contain high available carbohydrate with 55.62%, 30.93% and 19.29% in arils, pulp and peels respectively., which is significantly higher compared to Vuong (2000) (6.4g for fruit and 10.5g for arils) and Gunasekaran et al. (2014) (7.6%). Meanwhile, the peels contained the highest protein content (6.16%±0.26) followed by arils (5.76%±0.32) and pulp (4.57%±0.22), which is also significantly higher compared to Vuong (2000) (0.6 g for fruit and 2.1 g for arils) and Gunasekaran et al. (2014) (1.5%). Nevertheless, the gac arils in study, found to contain significant amount of fat content at 14.55%±0.27 to 29.97%±6.86 and low percentage in peels (0.96% to 2.17%) and pulp (0.69% to 2.47%), which is significantly higher compared to Vuong (2000) (0.1 g for fruit and 7.9% for arils), and Gunasekaran et al. (2014) (0.1%). The total dietary fibre found at the highest amount in peels (68.56%) compared to pulp (43.53%) and arils (20.55%), and significantly higher than Vuong (2000) (1.6 g for fruit and 1.8 g for arils) and Gunasekaran et al. (2014) (1.1%). For the total energy, peels, pulp and arils of gac fruit in the study contribute to 110.44 to 121.33 kcal/100g, 148.21 to 164.23 kcal/100g and 376.47 to 515.25 kcal/100g respectively. This findings was significantly higher compared to Vuong (2000) (29 kcal for fruit and 125 kcal for arils) and Gunasekaran et al. (2014) is only 37 kcal/100g. CONCLUSION There are several factors, such as geographical and climate differences, environmental factors, stage of maturity, as well as storage conditions might influence the nutritional contents of the samples. In conclusion, this preliminary study indicated that gac fruit grown in Malaysia has better nutritional content compared to other region, which pulp and arils of gac fruit can provide an important source of carbohydrate and minerals for human consumption, while arils have a good potential source of healthy edible oils.
ACKNOWLEDGEMENT I would like to thank you to Dr. Mohd Desa Hj. Hassim, CEO TFNet, Serdang, Malaysia; Dr. Mohd Fairulnizal, Head of CDNRC, IMR, Kuala Lumpur; Mdm. Vimala Balasubramaniam, Research Officer, IMR; Mdm. Sa’diah Hj. Yusof, JTMP, IMR; and Mr. Azman Asmat, Lab. Assistant at Food Biochemistry, UPM.
