Assessment of bioactive compounds and product development from major Garcinia spp. of Kerala

Abstract

The present study entitled “Assessment of bioactive compounds and product development from major Garcinia spp. of Kerala” was carried out in the Department of Postharvest Management, College of Agriculture, Vellayani during 2017-21 with the objective to assess the bioactive compounds in major Garcinia spp. of Kerala viz. G. gummi-gutta (malabar tamarind), G. mangostana (mangosteen), G. xanthochymus (yellow mangosteen) and development of value added products with nutraceutical importance. Primary and secondary metabolites present in pulp and pericarp of the three species were assessed. The G. mangostana recorded highest TSS for pulp as 20.83 0Brix and 27.93 0Brix in pericarp whereas the highest acidity was recorded in Garcinia xanthochymus rind (6.54%) and pulp (6.18%). Mangosteen fruit pulp recorded the highest vitamin C (33.80 mg 100g-1) and total sugar (13.31%) and the yellow mangosteen pulp noticed the highest protein content of 7.24 g 100g-1. Crude fibre (12.37%), fat content (1.35 mg 100g-1), total phenols (2603.68 mg GAE 100g - 1), antioxidant activity (92.27 %), total flavonoids (1.55mg QE g-1), Ca (1910.00 ppm), K (3323.33 ppm) and Fe (9.24 ppm) were found the highest in mangosteen pericarp. Twelve major sugars were quantified from the economic parts of the Garcinia fruits. Garcinia gummi-gutta fruits recorded fructose (8.85±0.028mg g-1) in the highest quantity followed by ribose (4.87±0.019 mg g-1) and glucose (3.14±0.033mg g-1). The prominent sugar was fructose in G. mangostana (28.163±0.813mg g-1) and G. xanthochymus (25.842±0.151 mg g-1). Organic acid profiling of the fruits revealed Hydroxy Citric Acid (HCA) as the major organic acid in G. gummi-gutta fruits (547.458±4.185mg g-1) and citric acid was the most abundant organic acid in G. mangostana (674.17±0.485 mg g-1) and G. xanthochymus fruit (680.361±0.863mg g-1). The phenolic profiling of Garcinia fruits showed p-coumaric acid as the major phenolic acid in G. gummi-gutta (104.81 μgg-1), G. xanthochymus (353.61 μgg- 1) and G. mangostana (335.70 μgg-1). A total of thirteen individual flavonoids were identified and quantified from selected Garcinia fruits and epicatechin (18.699±0.211 μgg-1), catechin (6.688±0.492 μgg-1) and luteolin (8.814±0.791 μgg-1) were the predominant individual flavonoids in G.gummi-gutta. Mangosteen fruit pulp recorded the highest quantity of hespertin (36.980 μgg-1) whereas naringenin (44.424±0.363 μgg-1) was the abundant flavonoids in G. xanthochymus fruits. Natural polyisoprenylated benzophenones such as garcinol and isogarcinol were isolated by column chromatography followed by crystallization from the hexane extract of G. indica fruits. Another benzophenone xanthochymol was isolated by column chromatography using hexane extract of G.xanthochymus fruits. The structural identification of the compounds was done by spectroscopic methods like UV-Vis, 1H NMR and 13C NMR. HPTLC densitometry method was used to compare and quantify the benzophenones in three major Garcinia species. Results showed that garcinol was the major benzophenone in G.gummi-gutta (7.53 %) and G. xanthochymus (8.26%) whereas G.mangostana fruits were high in isogarcinol (8.10%). The major xanthone, α-mangostin was quantified in mangosteen rind as 3.62 % on dry weight basis. The pigment was extracted from dried and powdered pericarp of ripe mangosteen fruits by the method of hot maceration where distilled water (aqueous extraction) and ethanol as solvents, acidified with citric acid (0.1% and 0.2%) and acetic acid (1% and 2%) at different levels. Based on higher extraction yield (28.57%), anthocyanin content (294.73 mg 100 g-1), total phenols (1549.55 mg GAE 100 g-1) and antioxidant activity (82.68%), colour extracted with acidified ethanol (2% acetic acid) was selected as the best solvent system and was further utilized as a natural colourant in Garcinia nectar formulations. For the development of nectar formulations from Garcinia spp., G. gummigutta rind, mangosteen pulp and G. xanthochymus pulp, was used at different fruit pulp concentration (15%, 20%) and TSS (150 Brix, 200 Brix, 250 Brix, 300 Brix). Biochemical quality parameters such as titratable acidity, vitamin C, total sugar, reducing sugar, antioxidant activity, total phenol content, total flavonoids and HCA were analyzed for all nectar formulations. Based on biochemical quality and sensory mean scores of the formulations, G. gummi-gutta nectar prepared with 20 % fruit and 200 Brix, Garcinia mangostana nectar formulation with 20% fruit with TSS 150 Brix and for G. xanthochymus fruit beverage prepared with 15% fruit and 200 Brix were selected as the best formulations for the supplementation of natural colour extracted from mangosteen pericarp. The selected nectar formulation of G. gummi- gutta and G. xanthochymus was added with 0.5% mangosteen pericarp colour extract whereas 0.3 % was added to G. mangostana nectar. Storage stability studies of the nectar formulations were conducted under room temperature along with control (formulation without addition of natural colour). During storage, TSS, titratable acidity, total sugar and reducing sugar parameters of the nectars were increased whereas vitamin C, total phenols and antioxidant activity showed a decreasing trend. The effect of light on colour stability of the nectars was studied and nectar stored in amber bottles retained more anthocyanin than in transparent glass bottles. The temperature stability studies revealed that with the increase in temperature and time, total anthocyanin content of the beverages decreased. Sensory quality analysis of the nectar formulation revealed that beverages added with natural colour extract recorded the highest sensory mean score for colour and overall acceptability without affecting the taste and flavour. Garcinia gummi-gutta fruit rind was utilized for preparation of various valueadded products viz. osmodehydrated rind, culinary paste and pickles. The effect of different osmotic concentrations (500 Brix and 700 Brix) and immersion time (24, 36 and 48 h) on mass transfer characters, and quality parameters of osmodehydrated rind were evaluated. The mass transfer characters viz. solid gain, water loss, and weight reduction were increased with increase in immersion time and osmotic concentration. Osmodehydrated products packaged in polypropylene were stored for a period of 3 months and storage stability studies were conducted. The TSS, acidity and sugars were increased during storage whereas HCA and antioxidant activity decreased. The storage study revealed that osmotic treatment, 700 Brix for 36 h exhibited highest acceptability and used for pickle development studies. The fresh malabar tamarind rind was used for the preparation of culinary paste with different levels of salt concentration (3%, 5%,7%, 9%) and without the addition of salt as control. The moisture content, HCA, and antioxidant activity were decreased meanwhile TSS, total sugar, reducing sugar, acidity and total flavonoids of the paste increased during storage. The paste prepared with 9% salt recorded the lowest browning index (31.52 %), bacterial load and the highest score for taste (8.33), flavour (8.27) and overall acceptability (7.87) after three months of storage. Sweet pickle from osmodehydrated (700Brix for 36 h) slices and sour pickle from fresh G.gummi-gutta rind were prepared and analysed for biochemical, microbial and sensory quality during storage of 2 months. The total sugar, reducing sugar, vitamin C and antioxidant activity of the pickles decreased during storage and both sweet and sour pickles were found acceptable. The major Garcinia spp. viz. G. gummi-gutta (malabar tamarind), G. mangostana (mangosteen), G. xanthochymus (yellow mangosteen) were found rich in bioactive compounds. The anthocyanin colour was effectively extracted from mangosteen pericarp with acidified ethanol and was used as a natural colourant in Garcinia fruit beverages. Value added products viz., osmodehydrated rind, culinary paste, sweet and sour pickles were developed from G. gummi-gutta rind with good acceptability and storage stability.