Pattern of phenolic content, antioxidant activity and senescence-related enzymes in granulated vs non-granulated juice-sacs of 'Kinnow' mandarin (Citrus nobilis x C. deliciosa).

'Kinnow' is a hybrid mandarin, developed at California (USA) but could not become successful there. However, it revolutionized citrus industry in India, Pakistan and Bangladesh. Recent reports indicate that like other citrus fruits, it also suffers from juice-sac granulation but exact cause of this malady is not known. Fully-mature 'Kinnow' fruits were harvested and observations on some physical and biochemical attributes were recorded and their relationship was established with occurrence of granulation. About 12.8 % 'Kinnow' fruits were affected by juice-sac granulation. Granulated fruits had higher average weight (178 ± 2.26 g), peel thickness (3.72 ± 0.23 mm), and less soluble solids concentrates (7.4 ± 0.21 %) than non-granulated fruits. Granulated fruits exhibited lower concentrations of total phenolics compounds (4.3 ± 0.56 mg 100(-1) g gallic acid equivalent fresh weigh) and antioxidants activity (1.78 ± 0.29 µmol Trolox g(-1) FW) but produced higher rates of carbon dioxide and ethylene, and exhibited higher activities of senescent-related enzymes such as lipoxygenase (LOX) (1.3 ± 0.31 µmoles min(-1) g(-1) FW) and pectin methylesterase (PME) (0.52 ± 0.12 µmol of NaOH g(-1) FW min(-1)) and had strong relationships with the occurrence of granulation. From this study, it can be concluded that total phenolics compounds, antioxidants and PAL enzyme activity have strongly negative co-relation; whereas, senescent-related enzymes such as LOX, and PME and rates of respiration or ethylene evolution have strongly positive relationships with the occurrence of granulation in 'Kinnow' mandarin.

Nutraceutical composition of Zizyphus mauritiana Lamk (Indian ber): effect of enzyme-assisted processing.

Zizyphus (Indian ber) is an excellent source of several phenolic compounds. The effect of two cell wall degrading enzymes, namely pectinase and viscozyme, on the nutraceutical composition of Zizyphus juice was investigated in the present study. Enzyme assisted processing significantly (P < 0.05) improved the juice yield, total soluble solids, total phenolics and total antioxidant activity (AOX). There was significant increase in recovery of antioxidants, to the tune of 70.51%, 66%, and 45% respectively in ascorbic acid, total phenolics and total flavonoids through viscozyme. The in-vitro total AOX of juice extracted via enzyme-assisted processing was 20.9 and 15.59 µmol Trolox/ml in ferric-reducing antioxidant power and cupric-reducing antioxidant capacity assays, respectively. There was 41% increase in AOX of juice extracted with enzyme over straight pressed juice. Results indicate that enzyme-assisted processing can significantly improve the functional properties of the Zizyphus juice.

Stemflow: A Source of Nutrients in some Naturally Growing Epiphytic Orchids of the Sikkim Himalaya.

A study on five naturally growing epiphytic orchids viz., Bulbophyllum affine Lindl., Coelogyne ochracea Lindl., Otochilus porrecta Lindl., Cirrhopetalum cornutum Lindl. and C. cornutum (var.) was carried out in the subtropical belt of Sikkim Himalaya. Stemflow leachates formed the main source of ammonium-N and nitrate-N for uptake by these orchids. Phosphorus concentration in the tissues of these orchids was high. Phosphate-P from stemflow does not seem to be a regular source of phosphorus for these orchids. Absorption/desorption results indicate that organic-N from stemflow leachates is not utilized by these orchids.