Bacterial stalk rot (BSR) of maize caused by Dickeya zeae is an important disease in northwest region of India. In the current study, eighty maize lines were evaluated for resistance against this disease. Of these, 20 were moderately resistant, 25 were moderately susceptible and the rest were highly susceptible to BSR. Six lines from each set were randomly selected. Activities of three antioxidant enzymes, viz. phenylalanine ammonia lyase (PAL), peroxidase (POX) and polyphenol oxidase (PPO) were analysed from these three sets of maize lines representing different levels of resistance. A trend of elevated activity of PAL, POX and PPO was observed in all the three sets of maize lines. The results showed significantly more activity of these three enzymes in moderately resistant than highly susceptible maize lines. The activity of PAL and PPO peaked after 48 hr and of POX after 72 hr of challenge inoculation by D. zeae in all the maize lines. The activity of these enzymes further correlated negatively with disease development. Our results show that PAL, POX and PPO play an important role in contributing towards resistance in maize against BSR.
K E Y W O R D Santioxidant enzymes, bacterial stalk rot, Dickeya zeae, maize, resistance
Durum wheat grain from the field is naturally contaminated with bacteria, yeast, and mold. The reduction in aerobic plate count (APC) and yeast and mold count (YMC) is often necessary before processing wheat. Gaseous ozone, ozonated water, and acetic acid solution are nontraditional antimicrobial agents for grains and are safe for humans and the environment. Better disinfection may be possible by applying antimicrobial agents to grain in a fluidized state. Fluidization increases the exposure of grain surfaces, resulting in uniform and quick contact of grain with antimicrobial agents. Therefore, a fluidized bed was developed with automated spraying system (to spray treatment waters), and a port for gaseous ozone injection. The pressures and velocities within the fluidized bed system were measured to characterize the system. The treatments used on fluidized grain were: distilled water (control), gaseous ozone (6 ppm), ozonated water (23 mg/L), gaseous ozone + ozonated water (6 ppm, 23 mg/L), acetic acid solution (0.5%), acetic acid + ozonated water (0.5%, 26 mg/L), and gaseous ozone + acetic acid + ozonated water (6 ppm, 0.5%, 26 mg/L). The last of these treatments was most effective with 1.7 and 3.3 log reduction in APC and YMC, respectively. This combined treatment can be used to replace the chlorinated water that industry uses during tempering of grain. Ozonated water alone resulted in a 0.3 log reduction in both APC and YMC. Gaseous ozone alone did not cause a significant reduction in APC and YMC.
Sugarcane with a high content of sugar is a potential substrate for making vinegar through alcoholic and acetous fermentation. As an alternative to the longer traditional batch scale vinegar fermentation, a fermentation process involving successive discontinuous cycles of acetification was developed. The cycles standardized for 3 days of shaking (75 rpm) and addition of (NH4) 2SO4 and KH2PO4 were recycled with previous lots of fermentation resulting in vinegar production with a time period of 7.6 days compared with 24 days of batch fermentation. The volatile's characterization of sugarcane vinegar identified 50 compounds with 24 esters, 4 alcohols, 2 phenols (aromatic hydrocarbons), 3 ketones, 6 alkene derivative, 3 carboxylic acids, 1 aldehyde and 8 miscellaneous compounds. Physicochemical characterization of vinegar revealed a maximum total phenol content of 67.09 Ϯ 1.21 mg/100 mL in control while ascorbic acid content of 108.49 Ϯ 1.11 mg/100 mL was best obtained in the treatment of shaking at 75 rpm along with supplements.
PRACTICAL APPLICATIONSThe result of this work will have practical applications in providing a less timeconsuming and highly efficient method for vinegar production thus, promoting an impetus to the setting up of natural vinegar production plants in this part of the country.
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