Post-harvest biodegradation of bioactive substances and antioxidant activity in microgreens

Low consumption of vegetables due to unavailability and unscrupulous application of chemicals and pesticides leads to malnutrition and chronic diseases. In this regards, microgreens technology could be a boon to mankind because they are grown in chemicals and pesticides free environment and offer functional food along with proper nutrient supply. But a little knowledge has been developed about the consumption period from harvesting, because being perishable in nature their bioactive substances and antioxidant activity get deteriorate. Therefore, the goal of this study was to explore the best consumption period of microgreens for obtaining the maximum bioactive substances (such as chlorophyll, ß-carotene and lycopene), vitamin C and the activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH). The experiment revealed that after 1st day of harvest the microgreens of four tested varieties (mustard, leaf mustard, radish and cabbage) showed the maximum bioactive substances such as total chlorophyll (8.22, 10.28, 7.62 and 7.63mg/100g respectively), ß-carotene (2.41, 2.88, 2.11 and 2.06 mg/100g respectively), lycopene (4.37, 5.24, 4.91 and 4.44mg/100g respectively), vitamin C (16.23, 13.17, 8.57 and 8.03mg/100g, respectively) and the activity of DPPH (0.75, 1.20, 2.90 and 3.57μg/ml respectively) whereas these substances deteriorated significantly on 3rd or 5th day of harvest. Considering all, it can be concluded that consumption of microgreens immediately after harvesting was the best time getting ample amount of bioactive substances, vitamin C and antioxidant (DPPH) activity

Cardioprotective molecule and bioactive compounds of some selected vegetables available in Bangladesh

Cardiovascular disease (CVD) is one of the leading causes of death and morbidity as well as imposing a huge economic burden at both country and household level. Upto 90% cardiovascular disease may be preventable if established risk factors are avoided. In this context, dietary nitrate from vegetables was highlighted as a potential candidate for cardio protection. Hence, by supplying dietary nitrate and other bio-active compounds to ease the risk of cardiovascular disease, present research work was carried out. Among the tested vegetables, the highest nitrate content (745 mg/100g) was determined in Indian spinach. In addition, Indian spinach also possesses more chlorophyll (150mg/100g), beta carotene (40mg/100g) and lycopene (34mg/100g) than other tested vegetables in the current study. In case of anti-oxidant content, Indian spinach showed the highest (103mg/100g) vitamin C content. Taken all together, Indian spinach may be a good and cheapest source of cardio protective molecule (nitrate) bioactive compounds to avoid risk of cardiovascular disease

Role of autophagy in hydrogen peroxide-induced cell death and starch synthesis in Physcomitrium

主指導教員 : 森安 裕二textapplication/pd

Evaluation of quality attributes of fresh and fermented bottle gourd peel as food-waste in processing industry

Fermentation of bottle gourd peel (BGP) was carried in 8% salt solution, 10% salt solution and 12% salt solution. During fermentation the acidity increased and pH decreased with the progression of fermentation time resulting in first order kinetics. Lowest rate of acid production was obtained in 12% salt solution (k value 0.0294) whereas highest was obtained in 10% salt plus 1%sugar solution (k value 0.0458). pH decreasing rate was faster in both 8% salt solution and 12% salt solution (for k value -0.015). The result of the proximate analysis of fresh BGP showed that moisture (%), ash (%), crude fiber (%), protein (%), pH, titrable acidity (%), total antioxidant scavenging activity (%), vitamin-C (%) and total phenolic content of bottle gourd peel were 91.38±0.015a, 1.27±0.025a, 1.25±0.015a, 2.8±0.122a, 6.78±0.02a, 0.0384±0.001a, 7.6±0.21a, 48.05 and 4.24 μgGAE/mg respectively. There were significant differences (p0.05) in case of ash and crude fiber. Fermented BGP samples were pickled in 5% acetic acid. During the pickling, acidity increased at first up to 14 days and then decreased slowly. pH decreased first and then increased slowly. Organoleptic taste testing showed that all the developed pickles were accepted by the panellists and all fermented pickles were rated as 'like moderately' whereas pickle of BGP fermented in 12% salt solution was more acceptable. During storage of pickles up to 3 months at room temperature there were no change in colour, flavour and no fungal growth was observed. The texture becomes softer in the third month. [J Bangladesh Agril Univ 2023; 21(2.000): 214-223

Hydrogen peroxide priming alleviates chilling stress in rice (Oryza sativa L.) by enhancing oxidant scavenging capacity

Chilling is a substantial stressor for plants. In fact, some biochemical reactions involved in growth and development of plant are sensitive to temperature. In particular, chilling stress represents a severe issue for plant growth and productivity and strategies to alleviate the stress is an important goal for agriculturists. While, hydrogen peroxide (H2O2) acts as a signalling molecule and its role in preventing several abiotic stresses like heat, salinity, drought etc. is well understood. Thus, the present study tested the effects of H2O2 priming in mitigation of chilling stress at germination and seedling stage of rice. The rice seeds were treated with H2O2 (5, 10 and 15 mM H2O2) solution for 24 h and exposed to chilling stress either for 6 h in 24 h or 12 h in 24 h for 7 days. Results revealed that, chilling stress seriously impeded germination indices (germination percentage, germination rate index, coefficient of velocity of germination and mean germination time), morphological parameters (shoot length, root length and fresh weight), total chlorophyll content and antioxidant enzymes (catalase and ascorbate peroxidase) activity. On the other hand, priming with H2O2 (5mM, 10mM and 15mM) displayed protective effects on germination indices and growth parameters and conferred a significant tolerance against chilling stress. Priming with H2O2 also significantly protected chlorophyll from chilling-induced degradation. Our results provide a strong foundation that priming with H2O2 confers a positive physiological effect by enhancing antioxidant enzymes capability (increased catalase and ascorbate peroxidase activity) of chilling stressed rice plant. Among the concentrations, 10 mM H2O2 performed relatively better in chilling stress alleviation. Therefore, this technique can be used for improved rice seedling production in northern part of Bangladesh under low temperature condition. [Fundam Appl Agric 2019; 4(1.000): 713-722

Hydrogen Peroxide Mediates Premature Senescence Caused by Darkness and Inorganic Nitrogen Starvation in Physcomitrium patens

Leaf senescence accompanied by yellowing and Rubisco degradation occurs prematurely in response to various stresses. However, signaling pathways between stress perception and senescence responses are not understood fully, although previous studies suggest the involvement of reactive oxygen species (ROS). While investigating the physiological functions of autophagy in Physcomitrium patens using wild-type (WT) and autophagy-deficient atg5 strains, we found that Physcomitrium colonies senesce prematurely under dark or nitrogen-deficient conditions, with atg5 senescing earlier than WT. In the present study, we measured cellular H2O2, and examined whether H2O2 mediates premature senescence in Physcomitrium colonies. Methyl viologen, an ROS generator, increased cellular H2O2 levels and caused senescence-like symptoms. H2O2 levels were also elevated to the same plateau levels in WT and atg5 under dark or nitrogen-deficient conditions. The ROS scavenger N-acetylcysteine and the ROS source inhibitor carbonyl cyanide m-chlorophenylhydrazone inhibited the increase in H2O2 levels as well as senescence. Upon transfer to a nitrogen-deficient medium, H2O2 levels increased earlier in atg5 than in WT by ~18 h, whereas atg5 yellowed earlier by >2 days. We conclude that the increased H2O2 levels under dark or nitrogen-deficient conditions mediate premature senescence in Physcomitrium but do not explain the different senescence responses of WT and atg5 cells

Amino Acids Supplied through the Autophagy/Endocytosis Pathway Promote Starch Synthesis in Physcomitrella Protonemal Cells

The physiological implications of autophagy in plant cells have not been fully elucidated. Therefore, we investigated the consequences of autophagy in the moss Physcomitrella by measuring biochemical parameters (fresh and dry weights; starch, amino acid, carbohydrate, and NH3 content) in wild-type (WT) and autophagy-deficient atg5 Physcomitrella cells. We found higher starch levels and a higher net starch synthesis rate in WT cells than in atg5 cells cultured in a glucose-containing culture medium, whereas net starch degradation was similar in the two strains cultured in a glucose-deficient culture medium. Additionally, the treatment of cells with the autophagy inhibitor 3-methyladenine suppressed starch synthesis. Loading bovine serum albumin into atg5 cells through endocytosis, i.e., supplying proteins to vacuoles in the same way as through autophagy, accelerated starch synthesis, whereas loading glutamine through the plasma membrane had no such effect, suggesting that Physcomitrella cells distinguish between different amino acid supply pathways. After net starch synthesis, NH3 levels increased in WT cells, although the change in total amino acid content did not differ between WT and atg5 cells, indicating that autophagy-produced amino acids are oxidized rapidly. We conclude that autophagy promotes starch synthesis in Physcomitrella by supplying the energy obtained by oxidizing autophagy-produced amino acids

Chitosan Coating Improves Postharvest Shelf-Life of Mango (<i>Mangifera indica</i> L.)

Mango is an extremely perishable fruit with a short postharvest time, and a considerable proportion of harvested mangoes become spoiled due to the postharvest decay in mango-producing areas of the world. The current study was designed to evaluate the effects of chitosan on the storage life of mango. Mango samples were coated with 750, 1000, and 1500 ppm chitosan solution, before storing them in the open or zip-bags under ambient and refrigeration conditions for different storage periods. Changes in different physical and chemical parameters were recorded to evaluate the treatments’ effectiveness in extending fruit shelf-life and sustaining postharvest quality of mangoes. The results showed that chitosan coating was able to reduce weight loss up to 65% in comparison to the uncoated control. Total mold and bacterial counts were also significantly lower in postharvest mangos when they were coated with chitosan compared to the uncoated samples. In addition, different fruit quality attributes, such as vitamin C content, titratable acidity, sugar content, ash, and protein content were also retained to a considerable extent by the chitosan coatings. Chitosan at refrigeration temperature (4 °C) with zip-bag packaging had a greater positive effect on fruit shelf-life, weight maintenance, and quality attributes than ambient temperature. Among the different coating concentrations, 1000 ppm chitosan solutions could provide better performance to extend the shelf-life of mango fruit while maintaining quality attributes. Altogether, our findings suggest that chitosan coating effectively prolongs the storage life of mango fruit and maintains fruit quality during storage, and offers promising potential for successful commercialization of this edible coating for mango growers and the industry