Advances in drying techniques for retention of antioxidants in agro produces.

Antioxidants are compounds that are essential for the human body which prevents cell from disease causing free radicals. Antioxidants are present in a wide range of fruits, vegetables, and spices. However, a considerable amount of antioxidants is lost during the post-harvest drying operation of agro produces for their shelf-life enhancement. Hence, retention of antioxidants becomes utmost importance in preserving the nutritional aspects of fruits and vegetables. Compared to conventional hot air drying, methods like freeze drying, vacuum drying, and dehumidified drying helps in the retention of antioxidants. However, the drawbacks prevalent in current drying practices, such as high-power consumption and high capital cost, could be eliminated by adopting novel drying mechanisms. This review focuses on various pretreatment methods like ultra-sonication, high pressure processing, pulsed electric field and ethanol treatment prior to drying operation helps in enhancing the drying efficiency with maximum retention of antioxidants. In addition, hybrid drying technologies such as microwave assisted drying, IR-radiated drying and electro-magnetic assisted drying methods also could significantly improve the retention of antioxidants.HIGHLIGHTSDrying is the most commonly adopted unit operation for enhancing the shelf life of perishable agro produces.However, drying is accompanied by loss of bioactive, color, texture, and sensory attributes.Compared to conventional drying techniques like hot air drying, methods like freeze drying, vacuum drying and dehumidified drying helps in the retention of antioxidants present in agro/food produces.Pretreatment methods like Ozonation, ultra-sonication, and UV radiation prior to drying are also found to improve the drying performance with good retention of antioxidants.Recent developments like microwave-assisted and IR-assisted drying methods perform well in the retention of antioxidants with less energy consumption.

Process development for the enrichment of curcuminoids in turmeric spent oleoresin and its inhibitory potential against LDL oxidation and angiotensin-converting enzyme.

Turmeric (Curcuma longa) contains biologically active colouring constituents, curcuminoids, which are isolated from the turmeric rhizome by solvent extraction. The mother liquor left after the separation of curcuminoids is known as turmeric spent oleoresin (SOT). The present study developed a method for the enrichment of curcuminoids in SOT. By using this method, curcuminoids in the SOT (8.4%) were doubled (17.5%). Presence of curcuminoids in enriched fraction was confirmed by high performance liquid chromatography (HPLC) and liquid chromatography coupled with mass spectroscopy analysis. Further studies on this fraction showed that it can effectively inhibit angiotensin-converting enzyme and low-density lipoprotein oxidation with IC(50) values of 19.45 µg/ml and 30.52 µg/ml, respectively. The results showed that curcuminoids enriched fraction (CEF) can reduce the risk of hypertension and cardiovascular diseases. In addition to this fraction, a turmerone-rich hexane fraction was also separated from the spent oleoresin.

Catecholaminergic activation of G-protein coupling in rat spinal cord: further evidence for the existence of dopamine and noradrenaline receptors in spinal grey and white matter.

[35S]GTPgammaS autoradiography of slide-mounted tissue sections was used to examine G-protein coupling in the rat spinal cord, as stimulated by dopamine, the D1 receptor agonist SKF 38393, noradrenaline, and noradrenaline in the presence of the alpha adrenoceptor antagonist, phentolamine. Measurements were obtained from the different laminae of spinal grey and from the dorsal, lateral, and ventral columns of white matter, at cervical, thoracic, and lumbar levels. At every level, there was a relatively strong basal incorporation of GTPgammaS in laminae II-III>lamina IV-X of spinal grey, even in presence of DPCPX to block endogenous activation by adenosine A1 receptors. Dopamine, and to a lesser degree SKF 38393, but not the D2 receptor agonist quinpirole, stimulated G-protein coupling in laminae IV-X. Both dopamine and SKF 38393 also induced a weak but significant activation throughout the white matter. In both grey and white matter, the activation by dopamine was markedly reduced in presence of a selective D1 receptor antagonist. Noradrenaline strongly stimulated coupling throughout the spinal grey at all levels, an effect that was uniformly reduced in the presence of phentolamine. With or without phentolamine, there was also significant stimulation by noradrenaline in the white matter. Under the same experimental conditions, alpha 1, alpha 2, and beta adrenergic receptor agonists failed to activate GTPgammaS incorporation in either grey or white matter. However, in the presence of selective alpha 1 or alpha 2 receptor antagonist, significant reductions of noradrenaline-stimulated GTPgammaS incorporation were observed in both grey and white matter. The beta antagonist propanolol reduced GTPgammaS incorporation in grey matter only. Thus, the results confirmed the existence of D1 dopamine receptors and of alpha 1, alpha 2, and beta adrenergic receptors in the grey matter of rat spinal cord. In white matter, they strongly suggested the presence of dopamine D1, and of alpha 1 and alpha 2 adrenergic receptors on glia and/or microvessels, that might be activated by diffuse transmission in vivo.

Influence of cultivar and maturity at harvest on the essential oil composition, oleoresin and [6]-gingerol contents in fresh ginger from northeast India.

Severe flooding of the Brahmaputra River during the monsoon season and continuous rainfall in the northeast region (NER) of India cause an enormous loss of ginger crop every year. In this context, the present study investigates the variation in the essential oil composition and oleoresin and [6]-gingerol contents in 10 different fresh ginger cultivars harvested at 6- and 9-month maturity from five different states of NER. Monoterpenes, sesquiterpenes, and citral composition in the essential oil were evaluated to ascertain their dependence upon the maturity of ginger. Except Mizoram Thinglaidum, Mizoram Thingria, Nagaland Nadia, and Tripura I ginger cultivars, all other cultivars showed an increase in the citral content during the maturity that was observed for the first time. At 6-month maturity, a higher undecanone level was found in Nagaland Nadia (7.36 ± 0.61%), Tripura I (6.23 ± 0.61%), and Tripura III (9.17 ± 0.76%) cultivars, and these data can be used as a benchmark to identify those immature varieties. Interestingly, the Nagaland Nadia cultivar showed higher ar-curcumene (9.57 ± 0.58%) content than zingiberene (5.84 ± 0.24%), which was unique among all cultivars. Ginger harvested at 9-month maturity from the Tripura II cultivar had the highest citral content (22.03 ± 0.49%), and the Meghalaya Mahima cultivar had the highest zingiberene content (29.89 ± 2.92%). The oleoresin content was found to decrease with maturity in all cultivars, except Assam Fibreless and Manipur I. Moreover, the highest oleoresin (11.43 ± 0.58 and 9.42 ± 0.63%) and [6]-gingerol (1.67 ± 0.03 and 1.67 ± 0.05 g) contents were observed for Tripura II and Nagaland Nadia, respectively. This study suggests that Tripura and Nagaland are the most ideal locations in NER for ginger cultivation to obtain high yields of oleoresin and [6]-gingerol contents and harvesting at the 6-month maturation will compensate for the loss of ginger crop caused by the Brahmaputra River flooding in NER every year.

In vitro antioxidant and inhibitory potential of Terminalia bellerica and Emblica officinalis fruits against LDL oxidation and key enzymes linked to type 2 diabetes.

The present study evaluated the free radical scavenging capacity and antioxidant potential of different solvent extracts (Hexane (HE), ethyl acetate (EA), methanol (ME), 70% methanol (MW) and Water (WA)) of Terminalia bellerica (TB) and Emblica officinalis (EB) fruits. Methanol extract (ME) of TB and EB fruits exhibited maximum scavenging activity against DPPH, superoxide, hydroxyl and nitric oxide radicals. Cell based antioxidant activity was assayed by flow cytometry using DCFH-DA as probe. Methanol extracts were also screened for their antidiabetic activity via inhibition of α-amylase, α-glucosidase and antiglycation assays. Results showed that ME of TB and EB can act as potent α-amylase and α-glucosidase inhibitor. Significant antiglycation activity also confirms the therapeutic potential of these extracts against diabetes. Both the extracts significantly inhibited the oxidation of LDL under in vitro conditions. Liquid chromatography-mass spectroscopy (LC-MS) analysis revealed that methanol extract of TB and EB contains ellagic acid and ascorbic acid as the major compound respectively.