1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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Subject: search.filters.subject.Hibiscus

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    Aqueous extraction of anthocyanins from hibiscus by coupling instantaneous pressure drop and microwave assisted process
    (Department of Processing and Food Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2023-04-01) Nasim Babu, B; Prince, M V
    Colours are used in food to enhance the quality to clout the consumer and also for balancing the colour loss during processing. Since the consumers are becoming aware of the various hazards of using synthetic colours, natural colours are gaining importance. The commonly used conventional extraction methods possess disadvantages such as low extraction efficiency and high extraction time. A swelling operation using ‘Instantaneous Pressure Drop’ process prior to extraction could produce high quality anthocyanin by improving the hydration kinetics and capacity. Microwave energy could be used effectively to mediate extraction of anthocyanin in place of conventional aqueous methods. The anthocyanin from Hibiscus were extracted by a coupled process of instantaneous pressure drop pre- treatment and microwave assisted extraction. The developed extraction system consists of a steam generation system, processing vessel, vacuum system and supporting frame. The steam generator produces steam from water using LPG as heating medium. Steam outlet from steam generator was connected to the processing vessel which accommodates the raw material. The vacuum system consists of a vacuum tank, vacuum pump, controlled instant pressure drop valve and associated measuring systems. The whole IPD equipment is supported by frame structure. A microwave oven was used as the microwave reactor. A Box-Behnken design of response surface methodology was employed to characterize and optimize the process parameters of the coupled extraction process and investigate the effect of independent variables viz., process pressure (0.56, 0.84 and 1.14 kg/cm2), treatment time (1, 2 and 3 min), microwave power (480, 720 and 960 W) and solvent- sample ratio (15, 27.5 and 40 ml/g). Optimisation of process parameters of the coupled process of anthocyanin extraction from Hibiscus was carried out using design expert software version 7.0.0, based on desirability analysis. From the analysis, a process pressure of 0.905 kg/cm2; treatment time of 2.272 minutes; microwave power of 707.302 W and solvent- sample ratio of 30.415 ml/g were found to be optimum values. The results revealed that the coupled IPD and microwave assisted process of extraction resulted in enhanced anthocyanin yield and antioxidant activity with increased redness as desired by anthocyanin pigment when compared to conventional extraction process. Beside the coupled process takes reduced time for extraction, thereby reduces the energy requirement and cost for the extraction process.
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    Morphological studies of different types of hibiscus rosasinensis L. and standradisation of propagation techniques
    (Department of Pomology Floriculture and landscaping, College of Horticulture, 1984) Verghese, C A; Aravindakshan, M
    The investigation on collection, morphological description and standardization of propagation techniques of different types of hibiscus were carried out in the Department of Pomology and Floriculture, College of Horticulture, during the period 1979 to 1981. Thirty four types and fourteen varieties of Hibiscus rosasinensis, two types of H. schizopetalous and one type of H. mutabilis were collected from different zones of Kerala, Tamilnadu and Karnataka and were maintained in the College garden. Since the types collected had no specific varietal names, morphological descriptions of all the fifty one collections were made. Considerable variation both in vegetative and floral characters were exhibited by different types in the collection. A key was prepared based on important distinguishing characters for identification of different types of hibiscus, Acc.3, Acc.5, Acc.13, Acc.29, Acc.32, Acc.33, Acc.42 and Acc.52 were found to produce very attractive showy flowers of different shades of colours. Acc.43 and Acc.45 were bushy types. Pollen viability of ten types of hibiscus were studied. Considerable variation existed with regard to pollen viability among different types. Maximum pollen viability of 89.8 per cent was observed in Acc.22 and minimum of 4.7 per cent in Acc.7. Rooting of stem cuttings were assessed under two treatment conditions, with leaves and without leaves. Retention of leaves had significant influence over the treatment without leaves on rooting of cuttings. The response of growth regulators, IAA, IBA and NAA on rooting of ten hibiscus types were studied. It was revealed that in quick dip method best performance was recorded by NAA 3000 ppm followed by IBA 5000 ppm and IAA 10000 ppm for rooting percentage, number and length of roots. In prolonged dip method, higher rooting percentage, root number, root length and root weight was observed when cuttings were treated with NAA 50 ppm, IBA 75 ppm and IAA 100 ppm. Out of two methods of growth regulator application, quick dip method was significantly superior to prolonged dip method. The types responded differently to growth regulator treatment, Acc.19 responded best while least response was exhibited by Acc.7. From the studies on air layering, it was revealed that maximum rooting percentage of 89.3 was exhibited by Acc.38 and minimum percentage of success by Acc.7. Air layering recorded better rooting than cutting without growth regulator treatment. But, it showed lower rooting percentage when compared to growth regulator treated cuttings.