Sunil Pareek

Postharvest biology and technology of pomegranate

Pomegranate is a subtropical and tropical fruit of great importance from a health point of view. Despite increasing consumer awareness of the health benefits of pomegranate, consumption of the fruit is still limited owing to poor postharvest handling, storage recommendations, short shelf life and quality deterioration during transportation, storage and marketing. The occurrence of physiological disorders such as husk scald, splitting and chilling injury is another challenge reducing marketability and consumer acceptance. Recently, notable work on postharvest biology and technology has been done. Pomegranate is highly sensitive to low-oxygen (<5 kPa) atmospheres, chilling injury and decay. One of the major problems associated with pomegranate fruit is excessive weight loss, which may result in hardening of the husk and browning of the rind and arils. To reduce chilling injury incidence and to extend storability and marketing of pomegranates, good results were obtained with polyamine, heat, salicylic acid, methyl jasmonate or methyl salicylate treatments prior to cold storage. This article reviews the maturity indices, changes during maturation and ripening, postharvest physiology and technology of pomegranate fruit as well as the various postharvest treatments for maintaining fruit quality.

Effect of water regime, mulch and kaolin on growth and yield of ber (Ziziphus mauritiana lamk)

Summary The experiment was conducted using uniform 9 year-old plants of ber (Ziziphus mauritiana L.) ‘Mundia’ on loamy sand soil at the Horticultural Research Farm,Asalpur, Jobner, (Jaipur-Rajasthan), India.The experiment continued for 2 years from June to March 1995–96 and 1996–97. The experiment consisted of 24 treatment combinations of three water regimes, four mulches and two kaolin treatments. A split-plot design used the irrigation treatments on the main plots, with sub-plots of mulch and kaolin treatments, with four replications having two trees per unit. Increasing levels of water significantly increased growth and productivity. Among various mulches, black polythene (M1) resulted in maximum growth and productivity. In contrast, kaolin improved only the productivity. The treatment combination of I2 (15 cm depth of irrigation) + M1 (black polythene) + K1 (6% kaolin spray) gave the highest fruit yield (13.1 t ha–1).

Fruit and Vegetable Waste: Bioactive Compounds, Their Extraction, and Possible Utilization: Fruit and vegetable waste…

Fruits and vegetables are the most utilized commodities among all horticultural crops. They are consumed raw, minimally processed, as well as processed, due to their nutrients and health-promoting compounds. With the growing population and changing diet habits, the production and processing of horticultural crops, especially fruits and vegetables, have increased very significantly to fulfill the increasing demands. Significant losses and waste in the fresh and processing industries are becoming a serious nutritional, economical, and environmental problem. For example, the United Nations Food and Agriculture Organization (FAO) has estimated that losses and waste in fruits and vegetables are the highest among all types of foods, and may reach up to 60%. The processing operations of fruits and vegetables produce significant wastes of by-products, which constitute about 25% to 30% of a whole commodity group. The waste is composed mainly of seed, skin, rind, and pomace, containing good sources of potentially valuable bioactive compounds, such as carotenoids, polyphenols, dietary fibers, vitamins, enzymes, and oils, among others. These phytochemicals can be utilized in different industries including the food industry, for the development of functional or enriched foods, the health industry for medicines and pharmaceuticals, and the textile industry, among others. The use of waste for the production of various crucial bioactive components is an important step toward sustainable development. This review describes the types and nature of the waste that originates from fruits and vegetables, the bioactive components in the waste, their extraction techniques, and the potential utilization of the obtained bioactive compounds.

Viral, Fungal and Bacterial Disease Resistance in Transgenic Plants

Continuing attention is being devoted to the development of substitute strategies in plant-disease management and reducing dependency on synthetic chemicals. Viral, fungal and bacterial diseases are unquestionably the most versatile for environmental adaption and in the destruction of plant growth. Among the strategies, resistance breeding has generated proven data and been exploited in depth. However, conventional methods alone are not sufficient to control the novel races of viral, fungal and bacterial pathogens in crops due to a scarcity in required crop variations. The current situation encourages the search for variation against biotic stress through identification of genes across species. Over the last two decades, significant efforts have been initiated in plant-disease management via genetic engineering. In addition, several molecular techniques have emerged to disentangle multifaceted plant-pathogen systems and associated disease-resistance candidate genes. Besides describing many promising candidate genes from viruses, fungi and bacteria, numerous plant disease-resistance genes have been identified and evaluated in crop improvement programs by transformation. Advancement in plant transformation techniques enables transferring useful genes for the rational creation of disease-resistant plants. Success has been achieved in transgenic crops against various diseases of important crop plants. This chapter describes genetically engineered plants and their resistant to viral, fungal and bacterial pathogens.

Content of bioactive compounds and their contribution to antioxidant capacity during ripening of pineapple (Ananas comosus L.) cv Esmeralda

Pineapple (Ananas comosus L.) cv Esmeralda is a commercially important fruit with many bioactive compounds like vitamin C, β-carotene, phenolic compounds and flavonoids, which have been reported only for fruits of commercial maturity. Our objective was to evaluate changes in concentration of main pineapple bioactives, their contribution to total antioxidant capacity and enzyme activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) during pineapple ripening. Fruits were grouped into four ripening stages (RS) according to their weight, size and percentage of yellow skin color (RS1: 100% green, RS2: up to 30% yellow, RS3: 30% - 75% yellow, RS4: 75% - 100% yellow). Vitamin C content initially increased, and decreased at RS4; β-carotene, phenolics and antioxidant capacity increased gradually. Phenolics contributed over 40% of antioxidant capacity, followed by vitamin C and β-carotene. Major phenolic compounds identified were gallic acid, catechin and epicatechin. PAL and POD activity increased with ripening and correlated with concentration of phenolics. No PPO activity was quantified. We concluded that ripening of pineapple cv Esmeralda alters the concentration of bioactive compounds. Phenolic compounds, particularly gallic acid, exert the most antioxidant capacity during all RS, even if other compounds have higher concentrations.

Modulatory Effects of Exogenously Applied Polyamines on Postharvest Physiology, Antioxidant System and Shelf Life of Fruits: A Review

Polyamines (PAs) are natural compounds involved in many growth and developmental processes in plants, and, specifically in fruits, play a vital role regulating its development, ripening and senescence processes. Putrescine (PUT), spermine (SPE), and spermidine (SPD) are prominent PAs applied exogenously to extend shelf life of fruits. They also originate endogenously during developmental phases of horticultural crops and simultaneously affect the quality attributes and shelf life. Their anti-ethylene nature is being exploited to enhance the shelf life when exogenously applied on fruits. In growth and development of fruits, PA levels generally fall, which marks the beginning of senescence at postharvest phase. PUT, SPE and SPD treatments are being applied during postharvest phase to prolong the shelf life. They enhance the shelf life of fruits by reducing respiration rate, ethylene release and enhance firmness and quality attributes in fruits. PAs have a mitigating impact on biotic and abiotic stresses including chilling injury (CI) in tropical and sub-tropical fruits. PAs are environment friendly in nature and are biodegradable without showing any negative effect on environment. Biotechnological interventions by using chimeric gene constructs of PA encoding genes has boosted the research to develop transgenic fruits and vegetables which would possess inherent or in situ mechanism of enhanced biosynthesis of PAs at different stages of development and thereby will enhance the shelf life and quality in fruits. Internal and external quality attributes of fruits are improved by modulation of antioxidant system and by strengthening biophysical morphology of fruits by electrostatic interaction between PAs and phospholipids in the cell wall.

Nutritional and Biochemical Composition of Lychee ( Litchi chinensis Sonn.) Cultivars

Abstract Lychee (Litchi chinensis Sonn.) is cultivated commercially in more than 20 countries. Important lychee growing countries are China, India, Vietnam, Thailand, and South Africa. Many commercial varieties are growing in these countries, few of important ones are ‘Mauritius’, ‘McLeans Red’, ‘Muzaffarpur’, ‘Wai Chee’, ‘Kwai May Pink’, ‘Kwai May Red’, ‘Souey Tung’, ‘Bengal’, and ‘Haak Yip’. These cultivars exhibit significant differences in nutritional composition, particularly for minerals, phenolics, antioxidants, and volatile compounds. Still it is felt that there is a lack of sufficient literature and studies on this aspect of lychee fruit cultivars. Only phenolics and to some extent volatiles have been studied. Many of the studies appeared in local journals or in vernacular languages. In this chapter, up-to-date detailed information is provided on lychee cultivars, botanical aspects, sugars, organic acids, ascorbic acid, minerals, phenolics, flavonoids, antioxidants, and volatile compounds.

Current Status of Bacillus thuringiensis : Insecticidal Crystal Proteins and Transgenic Crops

Bacillus thuringiensis (Bt) is used to control agriculturally-important pests. It is a Gram positive spore-forming bacterium which produces parasporal proteinaceous inclusions during the sporulation phase. These crystalline parasporal inclusions are toxic to a wide spectrum of insects including the orders Lepidoptera, Coleopteran, Diptera, etc. The Bt insecticide proteins are toxic only after ingestion by the susceptible insects. The main steps involved when the Cry protein is ingested by the insect is comprised of solubilization of the protoxin, its enzymatic activation by terminal cleavage, receptor binding in brush border membrane of the midgut, pore formation, consequent disruption of ionic potential and destruction of the epithelial membrane leading to cell death. The first discovery of Bt was in 1901 when Ishiwata discovered a bacterium in Japan and in 1915, Berliner in Germany renamed it as Bacillus thuringiensis. Following a brief introduction, this chapter addresses the classification, the general structure of Cry toxin, its mode of action, strategies to improve the insecticidal activity of Cry proteins, transgenic plants developed using Bt genes, resistance to Bt toxins and resistance management, and an overall brief account of Bt and its insecticidal proteins, from 1901 to the present.

Date Palm Status and Perspective in India

Cultivation of the date palm in India goes back to the fourth century BC when Alexander the Great brought this fruit to India. The date palm has great socioeconomic importance and nutritional value in the Thar Desert, particularly in the Kutch region of Gujarat and western Rajasthan. Before 1947, India was a major date producer in the world. However, with independence and the partition that year, most of the date palm-growing areas became part of Pakistan. Subsequently, India became the largest world date importer. Over the last five decades, significant research has been done on date palm cultivation led by the Indian Council of Agricultural Research (ICAR) through the All India Coordinated Research Project (AICRP). Almost all the date cultivars grown in India were introduced from the Arabian Gulf and Middle Eastern countries. There is high potential for increasing the production area of date palm in India to fulfill local demand and to produce dates for export. Presently, the Rajasthan and Gujarat State governments and the private sector are convinced of the potential of date production and are striving to establish commercial date plantations and to promote date production. A public-private partnership has been established to boost production through tissue culture of date palms. Despite its important role in arid lands of the country and the efforts made, date palm cultivation, production, processing, and marketing are still beleaguered with several problems. The low quality of cultivars, non-availability of tissue-cultured plants, poor farm management, pests, diseases, lack of organized marketing, and insufficient applied research are major constraints of the date palm in India. This chapter discusses the current status, constraints, and approaches that can be used to develop the date palm industry in India.

Physiological responses of Indian jujube (Ziziphus mauritiana Lamk.) fruit to storage temperature under modified atmosphere packaging

BACKGROUND The effect of storage temperature on physiological responses in Indian jujube (Ziziphus mauritiana Lamk. cv. Gola) fruit was investigated. Freshly harvested fruits at physiological maturity characterised by colour-turning stage were stored at ambient temperature, 12 and 6 °C for 21, 35 and 35 days respectively. Headspace O2, CO2 and C2H4, moisture content, respiration, ethylene production, firmness, tristimulus colour, chroma, hue angle and chilling injury index were monitored during fruit storage. RESULTS Rates of respiration and ethylene production increased after 1 week of storage at ambient temperature, while peaks were observed after 2 weeks at 12 and 6 °C. Headspace O2 decreased continuously during storage, while CO2 and C2H4 increased at all storage temperatures. Moisture content and firmness also decreased during storage. Hunter L* values increased during storage, which correlated with the darkening of fruit colour. Fruit stored at ambient temperature did not show any chilling injury symptoms, while chilling injury appeared on day 28 under 12 °C storage and on day 21 under 6 °C storage. CONCLUSION Indian jujube fruit showed high rates of respiration and ethylene production that were significantly affected by different storage temperatures. Lower temperatures increased the shelf life of the fruit, but chilling injury was a problem under 6 °C storage. Indian jujube fruit could be stored at 6 °C for up to 35 days if chilling injury could be alleviated.