Detection of gamma radiation processed onion during storage using propidium iodide based fluorescence microscopy.

The determination of absorbed dose in gamma radiation processed onion (treated with 20-100 Gy for sprout inhibition) during storage is an important regulatory requirement to control unfair practices. To address this problem, a microscopy based method was developed using propidium iodide (PI) staining of onion adaxial epidermis. A proportional radiation dose dependent increase in nuclei count was observed during ambient (26 ± 2 °C) and low (2 ± 1 °C) temperature storage. The method was validated and dose of radiation could be determined accurately in stored onions using blind tests. During mechanism studies, boron-dipyrromethene (BODIPY) dye staining and malondialdehyde (MDA) estimation showed dose dependent increase in peroxidation of membrane lipids. The fluorescein diacetate (FDA) stained onion adaxial epidermis showed decrease in fluorescence indicating lowering of physiological activity. Enzyme peroxidase (POD), phenylalanine ammonia lyase (PAL) activities and phytochemicals (phenolics, flavonoids, ascorbic acid and pyruvic acid) did not change significantly with increasing dose of gamma radiation.

Pullulan or chitosan based active coating by incorporating polyphenols from lemon peel in raw poultry meat.

Dip coating with pullulan and chitosan in combination with lemon peel polyphenols (LPP) was attempted for shelf life extension of raw poultry meat. Control samples demonstrated bacterial lag phase and shelf life of 1.3 and 1 day, respectively at 4 °C. Meat samples coated with pullulan or chitosan in combination with 1% LPP led to an increased bacterial lag phase; thereby extending the shelf life of meat by 6 and 14 days, respectively. Significant (p < 0.05) reduction in lipid peroxidation in comparison with control was also observed due to dip treatment. Treated samples maintained values of < 1 mg kg-1 malondialdehyde for thiobarbituric acid reactive substances during the entire storage period. No significant (p > 0.05) change in colour, weight loss and pH of treated samples during storage was noted. Dip coated samples maintained acceptable sensory quality during the entire storage period. This study indicates that use of LPP for shelf life extension of raw meat could be a practical proposition.

Microbial quality assessment of minimally processed pineapple using GCMS and FTIR in tandem with chemometrics.

Microbial quality is the critical parameter determining the safety of refrigerated perishables. Traditional methods used for assessing microbial quality are time consuming and labour intensive. Thus rapid, non-destructive methods that can accurately predict microbial status is warranted. Models using partial least square regression (PLS-R) from chemical finger prints of minimally processed pineapple during storage obtained by Headspace Solid Phase Microextraction Gas Chromatography Mass Spectrometry (HS-SPME-GCMS), Fourier Transform Infrared (FTIR) spectroscopy and their data fusion are developed. Models built using FTIR data demonstrated good prediction for unknown samples kept under non-isothermal conditions. FTIR based models could predict 87 and 80% samples within ±1 log CFU/g for TVC and Y&M, respectively. Analysis of PLS-R results suggested the production of alcohols and esters with utilization of sugars due to microbial spoilage.

Methylation of guar gum for improving mechanical and barrier properties of biodegradable packaging films.

Improving functional properties of biopolymers for use as environment friendly packaging is an area of current interest. Biodegradable films with improved barrier and mechanical properties were prepared from methylated guar gum. Methylation resulted in structural modification of guar gum (GG) promoting greater crystallization thereby enhancing thermal stability towards decomposition. Reduction in radius of gyration (Rg), weight average molecular weight (Mw), and an increase in polydispersity index (PDI) were also observed due to methylation. Methylated guar gum (MGG) films exhibited 40% lower water vapor transmission rate (WVTR) as compared to control purified guar gum (PGG) films. Films prepared by partial replacement of PGG with MGG (10, 25, 50, 75 and 100% w/w) showed gradual improvement in percent elongation. The study gives an insight on the role of methylation in enhancing barrier and mechanical properties of GG based biodegradable films for possible application in food packaging.

GC-MS olfactometric characterization of odor active compounds in cooked red kidney beans (Phaseolus vulgaris).

Red kidney beans are a staple pulse crop well known for its unique flavor characterized by kidney bean like, smoky, sulfury and earthy aroma notes. However, nature of compounds responsible for the unique beany odor of the cooked pulse has not been established. Steam distillation extracts of red kidney beans were subjected to Gas-chromatography olfactometry (GC-O) techniques namely detection frequency and aroma extract dilution analysis (AEDA). GC-O results suggest that methional with flavor dilution (FD) factor 21 is responsible for imparting the characteristic odor of the cooked red kidney beans. Apart from this p-vinyl guaiacol (FD 13) was identified as most important contributor towards smoky odor note. Sulfury note was mainly contributed by diethyl sulfide (FD 10) while 2-ethyl-3-methyl pyrazine (FD 13) was identified to be responsible for earthy note in cooked red kidney beans. Contribution of these compounds in characteristic aroma of cooked red kidney beans is reported here for the first time.

Development of guar gum based active packaging films using grape pomace.

The objective of this study was to develop biodegradable active film to improve the shelf-life of minimally processed fresh-produce. Guar gum (GG) based films with improved properties were fabricated by employing tween-80 (0.88%) as emulsifier, nanoclay (13.9%) as reinforcement, beeswax (1.21%) for hydrophobicity, glycerol (3.07%) as plasticizer, and grape pomace extract (5%) as active ingredient (%w/w of GG). Active films had a tensile strength of 122 MPa and water vapor transmission rate of 69 gm-2d-1. Films demonstrated significant antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Salmonella Typhimurium. The 2 kGy irradiated minimally processed pomegranate arils packed in film demonstrated a shelf-life of 12 days as compared to 4 days for unirradiated samples. The observed improvement in shelf-life was due to a radiation-induced release of antimicrobial volatiles from active films as confirmed by headspace analysis using GC-MS. Suitability of active films for food irradiation applications is thus demonstrated.

Debittering of bitter gourd juice using ß-cyclodextrin: Mechanism and effect on antidiabetic potential.

Triterpene glycosides namely momordicoside K and momordicoside L causes bitterness in bitter-gourd thereby reducing its consumer acceptance. Reducing bitterness of the juice by addition of ß-cyclodextrin (0.25-2%) was attempted and its effect on sensory quality, total phenolic content, antioxidant activity and antidiabetic potential was evaluated. Juice with 1.5% ß-cyclodextrin demonstrated highest score (7.7 ±â€¯0.3) for sensory acceptability compared to the control (3.8 ±â€¯0.7). A significantly (p < 0.05) higher total phenolic content and antioxidant activity was observed. A marginal (10%) but significant (p < 0.05) reduction in α-glucosidase inhibition activity without affecting α-amylase activity was noted. Results from NMR, ROESY and FTIR studies indicated formation of an inclusion complex by interaction of hydrophobic triterpenoidal region of momordicosides with ß-cyclodextrin.

Effect of cooking on aroma profile of red kidney beans (Phaseolus vulgaris) and correlation with sensory quality.

Volatile aroma compounds of three varieties of red kidney beans (Phaseolus vulgaris) namely Kashmiri red, Sharmili and Chitra were extracted in raw state using solid-phase microextraction (SPME) and cooked state using simultaneous distillation extraction (SDE). During cooking a significant (p<0.05) reduction in the content of several aldehydes, alcohols and terpene hydrocarbons while an increase in content of various sulfurous compounds, terpene alcohols, ketones and pyrazines was noted. Descriptive sensory analysis showed that the maximum intensity of 'kidney bean', 'earthy' and 'smoky' odour was observed in Kashmiri red while Sharmili variety was characterised by 'sulfurous' odour. Correlation of volatile profile data with descriptive sensory analysis and odour activity values clearly established the role of compounds, such as methanethiol, diethyl sulfide, dimethyl disulfide, methional and dimethyl trisulfide, in contributing to 'cooked kidney bean' aroma, while dimethyl sulfoxide, dimethyl sulfone and ethyl methyl sulfone were responsible for 'sulfurous' aroma.

Aliphatic glucosinolate synthesis and gene expression changes in gamma-irradiated cabbage.

Glucosinolates, found principally in the plant order Brassicales, are modulated by different post-harvest processing operations. Among these, ionizing radiation, a non-thermal process, has gained considerable interest for ensuring food security and safety. In gamma-irradiated cabbage, enhanced sinigrin, a major glucosinolate, has been reported. However, the molecular basis of such a radiation induced effect is not known. Herein, the effect of radiation processing on the expression of glucosinolate biosynthetic genes was investigated. RT-PCR based expression analysis of seven glucosinolate biosynthetic pathway genes (MYB28, CYP79F1, CYP83A1, SUR1, UGT74B1, SOT18 and TGG1) showed that CYP83A1, MYB28, UGT74B1, CYP79F1 and SUR1 were up-regulated in irradiated cabbage. The content of jasmonates, signalling molecules involved in glucosinolate induction was, however, unaffected in irradiated cabbage suggesting their non-involvement in glucosinolate induction during radiation processing. This is the first report on the effect of gamma irradiation on the expression of glucosinolate biosynthetic genes in vegetables.

Shelf life extension of minimally processed ready-to-cook (RTC) cabbage by gamma irradiation.

Gamma irradiation (0.5-2.5 kGy) in combination with low temperature (4-15 °C) storage was attempted to increase shelf life of ready-to-cook shredded cabbage wrapped in cling films. A maximum extension in shelf life of 8 days, while retaining the microbial and sensory quality, was obtained with an irradiation dose of 2 kGy and storage at 10 °C. Gamma irradiation also inhibited browning of shredded cabbage at their cut edges resulting in enhanced visual appeal. An increase in total antioxidant activity was observed with respect to DPPH and hydroxyl radical scavenging ability while the nitric oxide radical scavenging activity and ferric reducing property remained unaffected with irradiation. Total phenolic, flavonoid and vitamin C content remained unchanged due to irradiation. No significant migration of additives from cling films into stimulant water was observed up to a radiation dose of 2 kGy thus demonstrating the feasibility of such films for above applications.

Antioxidant Compounds in Traditional Indian Pickles May Prevent the Process-Induced Formation of Benzene.

Pickles in the Indian market contain ascorbic acid from the raw material used and benzoate as an added preservative that are involved in the formation of benzene in soft drinks. In this work, 24 market pickle samples were surveyed for benzene content, as well as its precursors and other constituents that influence its formation. The analysis showed that pickle samples were high in acid content (low pH) and showed significant amount of ascorbic acid, minerals (Cu and Fe), and benzoic acid present in them. Also, most samples exhibited high antioxidant activity that might be attributed to the ingredients used, such as fruits and spices. The solid-phase microextraction headspace gas chromatography-mass spectrometry method was developed in-house for benzene analysis. Eleven of 24 samples had benzene, with the highest concentration of 4.36 ± 0.82 µg of benzene per kg of pickle for a lime pickle that was also reported to have highest benzoic acid and considerably less hydroxyl radical ((•)OH) scavenging activity. However, benzene levels for all 11 samples were considerably below the World Health Organization regulatory limit of 10 µg/kg for benzene in mineral water. Studies on model systems revealed that the high antioxidant activity of Indian pickles may have had a strong inhibitory effect on benzene formation.

Enhancing antioxidant activity, microbial and sensory quality of mango (Mangifera indica L.) juice by γ-irradiation and its in vitro radioprotective potential.

Gamma irradiation is an effective method currently being used for microbial decontamination and insect disinfestations of foods. In the present study, mango (Mangifera indica L.) juice was irradiated at doses of 0, 1.0, 3.0 and 5.0 kGy and microbial load, total polyphenols, flavonoids, ascorbic acid content, antioxidant activities, colour and sensory properties were evaluated immediately after irradiation and also during storage. Microbiological assay of the fresh and stored mango juice showed better quality after γ-irradiation. The total polyphenols and flavonoids were significantly (p < 0.05) increased while the ascorbic acid content decreased with the irradiation doses applied. As a result of γ-irradiation, a significant increment in gallic, syringic and chlorogenic acids and a significant reduction in ferulic and synapic acids were noted when analyzed by HPLC. In vitro antioxidant potentials were measured using DPPH, FRAP and NO scavenging assays; the results showed significant enhancement in the activities after irradiation, that correlated well with the increase in phenolic and flavonoid content. γ-irradiation improved the colour of mango juice without any adverse changes in the sensory qualities. Significant in vitro plasmid DNA protection was observed in the presence of mango juice against radiation induced damage, even at the dose of 5 kGy. This study confirmed the potential of γ-irradiation as a method for microbial decontamination and improving the quality of the mango juice without compromising on the sensory attributes.

Allyl isothiocyanate enhances shelf life of minimally processed shredded cabbage.

The effect of allyl isothiocyanate (AITC), in combination with low temperature (10°C) storage on post harvest quality of minimally processed shredded cabbage was investigated. An optimum concentration of 0.05µL/mL AITC was found to be effective in maintaining the microbial and sensory quality of the product for a period of 12days. Inhibition of browning was shown to result from a down-regulation (1.4-fold) of phenylalanine ammonia lyase (PAL) gene expression and a consequent decrease in PAL enzyme activity and o-quinone content. In the untreated control samples, PAL activity increased following up-regulation in PAL gene expression that could be linearly correlated with enhanced o-quinone formation and browning. The efficacy of AITC in extending the shelf life of minimally processed shredded cabbage and its role in down-regulation of PAL gene expression resulting in browning inhibition in the product is reported here for the first time.

Mechanical and barrier properties of guar gum based nano-composite films.

Guar gum based nano-composite films were prepared using organically modified (cloisite 20A) and unmodified (nanofil 116) nanoclays. Effect of nanoclay incorporation on mechanical strength, water vapor barrier property, chromatic characteristics and opacity of films was evaluated. Nano-composites were characterized using X-ray scattering, FTIR and scanning electron microscopy. A nanoclay concentration dependent increase in mechanical strength and reduction in water vapor transmission rate was observed. Films containing nanofil 116 (2.5% w/w guar gum) and closite 20A (10% w/w guar gum) demonstrated a 102% and 41% higher tensile strength, respectively, as compared to the control. Lower tensile strength of cloisite 20A films as compared to nanofil 116 films was due to its incompatibility with guar gum. X-ray scattering analysis revealed that interstitial spacing between nanofil 116 and cloisite 20A sheets increased due to intercalation by guar gum polymer. This resulted in improved mechanical and barrier properties of nano-composites compared to control.

Gamma irradiation inhibits wound induced browning in shredded cabbage.

Gamma-radiation induced browning inhibition in minimally processed shredded cabbage stored (10 °C) for up to 8 days was investigated. γ-irradiation (2 kGy) resulted in inhibition of browning as a result of down-regulation (1.4-fold) in phenylalanine ammonia lyase (PAL) gene expression and a consequent decrease in phenylalanine ammonia lyase (PAL) activity. Activity of polyphenol oxidase and peroxidase, total and individual phenolic content as well as o-quinone concentration were, however, unaffected. In the non-irradiated samples, PAL activity increased as a consequence of up-regulation of PAL gene expression after 24 and 48 h by 1.2 and 7.7-fold, respectively, during storage that could be linearly correlated with enhanced quinone formation and browning. Browning inhibition in radiation processed shredded cabbage as a result of inhibition of PAL activity was thus clearly demonstrated. The present work provides an insight for the first time on the mechanism of browning inhibition at both biochemical and genetic level.

Mechanism of cytotoxicity by Psoralea corylifolia extract in human breast carcinoma cells.

Psoralea corylifolia has been widely used in herbal medicine, and a few studies show its anticancer activity. However, the detailed mechanism of the anticancer activity of P. corylifolia seed extract (PC extract) was not studied. This study evaluates the anticancer activity and underlying mechanism of PC extract in a human breast cancer cell line (MCF7). PC extract caused a concentration-dependent decrease in the proliferation of MCF7 cells and an increase in apoptotic death as measured by annexin-V-FITC and TUNEL assays. Increased cleavage of poly(ADP-ribose) polymerase in cells treated with PC extract further confirmed the apoptotic mode of cell death. There was a decrease (~2-fold) of mitochondrial membrane potential in cells treated with PC extract. In cells treated with PC extract, an increase in intracellular reactive oxygen species (ROS) and a decrease in mitochondrial ROS was observed. A significant decrease in ATP (~1.8-fold) was observed in extract-treated cells. Moreover, MCF7 cells treated with extract showed cleavage of caspase-9 and caspase-7, upregulation of Bax, release of cytochrome-c, and loss of mitochondrial integrity. Taken together, these results suggest the involvement of the mitochondrial pathway in PC extract-induced apoptosis in MCF7 cells.

Effect of post harvest radiation processing and storage on the volatile oil composition and glucosinolate profile of cabbage.

Effect of radiation processing (0.5-2 kGy) and storage on the volatile oil constituents and glucosinolate profile of cabbage was investigated. Among the volatile oil constituents, an enhancement in trans-hex-2-enal was noted on irradiation that was attributed to the increased liberation of precursor linolenic acid mainly from monogalactosyl diacyl glycerol (MGDG). Irradiation also enhanced sinigrin, the major glucosinolate of cabbage that accounted for the enhanced allyl isothiocyanate (AITC) in the volatile oils of the irradiated vegetable. During storage the content of trans-hex-2-enal increased immediately after irradiation and then returned to the basal value within 24h while the content of sinigrin and AITC increased post irradiation and thereafter remained constant during storage. Our findings on the enhancement in potentially important health promoting compounds such as sinigrin and AITC demonstrates that besides extending shelf life and safety, radiation processing can have an additional advantage in improving the nutritional quality of cabbage.

Radiation dose dependent change in physiochemical, mechanical and barrier properties of guar gum based films.

Mechanical and water vapor barrier properties of biodegradable films prepared from radiation processed guar gum were investigated. Films prepared from GG irradiated up to 500 Gy demonstrated significantly higher tensile strength as compared to non-irradiated control films. This improvement in tensile strength observed was demonstrated to be due to the ordering of polymer structures as confirmed by small angle X-ray scattering analysis. Exposure to doses higher than 500 Gy, however, resulted in a dose dependent decrease in tensile strength. A dose dependent decrease in puncture strength with no significant differences in the percent elongation was also observed at all the doses studied. Water vapor barrier properties of films improved up to 15% due to radiation processing. Radiation processing at lower doses for improving mechanical and barrier properties of guar based packaging films is demonstrated here for the first time.

Hydrophobic derivatives of guar gum hydrolyzate and gum Arabic as matrices for microencapsulation of mint oil.

Guar gum hydrolyzate (GGH) modified with n-octenyl succinic anhydride (OSA) and oleic acid having induced hydrophobicity was evaluated for encapsulation of mint oil and compared with gum Arabic (GA) and GA-OSA as wall material. Spray dried microcapsules prepared with these wall materials were evaluated for qualitative changes by principal component analysis and for percent retention of mint oil during 8-week storage. Results revealed that microcapsules with GGH-OSA and GGH-oleate showed slightly lower retention of mint oil as compared to GA. GA-OSA microcapsules showed better retention of mint oil than GA itself, as observed from the t1/2, the time required for the mint oil to come down to 50% of its original content. The t1/2 of mint oil in microcapsules of GA, GGH-oleate, GGH-OSA and GA-OSA was 26.12, 23.50, 24.11 and 29.67 weeks, respectively. The results suggested that GGH-OSA has the potential to replace gum Arabic for encapsulation of mint oil.

Evaluation of antioxidant activity and characterization of phenolic constituents of Phyllanthus amarus root.

The antioxidant property of the 70% aqueous ethanol extract of Phyllanthus amarus roots and its ether-soluble, ethyl acetate-soluble, and aqueous fractions were investigated by various in vitro assays. The root extracts showed higher DPPH, hydroxyl, superoxide, and nitric oxide radical scavenging and reducing power activity. Among all the samples, the ethyl acetate-soluble fraction demonstrated highest radical scavenging activity and total phenolics content. Twenty-eight different phenolic compounds were identified by LCMS/MS analysis of the ethyl acetate-soluble fraction. The majority of the compounds were found to exist as their glycosides, and many of these were gallic acid derivatives. Free epicatechin and gallic acid were also identified in the ethyl acetate-soluble fraction. The present investigation suggested that P. amarus root is a potent antioxidant and can be used for the prevention of diseases related to oxidative stress.