FORMULATION AND SENSORY EVALUATION OF HERB TEA FROM MORINGA OLEIFERA, HIBISCUS SABDARIFFA AND CYMBOPOGON CITRATUS
This research is on Formulation and sensory evaluation of herb tea from moringa oleifera, hibiscus sabdariffa and cymbopogon citratus. The sensory appeal of tea, like all food products, is an important consideration in new product development. Tea in general and herb tea in particular, are gaining increasing consumer attention due to a growing awareness of health benefits derived from their consumption. Even though several underutilized plants exist with potential for processing into herb tea, research in product development of herb teas is limited. The objectives of the study were (1) to conduct chemical analyses on three herbs – Cymbopogon citratus leaves, Hibiscus sabdariffa calyces and Moringa oleifera leaves – in order to assess their potential for food product development; (2) to conduct acceptance tests on herb tea prepared from formulations of the herbs; and (3) to generate descriptive vocabulary on the sensory properties of herb tea. The herbs were unblanched and solar-dried. Standard methods were used to measure proximate parameters, water soluble extractives (WSE), light petroleum extractives (LPE), pH, total polyphenolics content (TPC) and minerals (Ca, Fe, Cu and Zn). Fifty (50) untrained panelists conducted acceptance tests on infusions from nine formulations and one control, and a nine-member trained panel conducted descriptive tests on infusions from three selected blends. Results of chemical analysis revealed that Moringa, Roselle and Lemon grass had, respectively, TPC of 35.70 mg/g, 27.81 mg/g and 15.37 mg/g; WSE of 7.44%, 12.38% and 4.07%; LPE of 3.48%, 2.71% and 4.1%; pH of 5.47, 2.73 and 4.53.
Mineral analyses revealed that Moringa, Roselle and Lemon grass had, respectively, Ca of 412.5 mg/100g, 294 mg/100g and Fe of 12.93 mg/100g; 24.26 mg/100g and 11.58 mg/100g. A total of seventeen (17) descriptors were generated, defined and referenced for herb tea comprising six (6) appearance, three (3) aroma, one (1) flavour, five (5) taste and two (2) mouthfeel descriptors. Herb tea brewed from product 532 (50% Moringa, 30% Roselle and 20% Lemon grass) was the most preferred in colour, flavour, astringency and overall sensory properties while the control (100% Moringa) brewed the least preferred herb tea in most of the sensory attributes. Product 532 was predominantly reddish in colour (12.56) while the control was yellowish (11.93). Product 532 had high mean scores for Turbidity (12.67), Herbal aroma (11.41), Citrus aroma (11.30), Sour taste (12.15) and Astringency (11.41) while the control had significantly low scores for most of these attributes (≤ 2.33). Herb tea from blend of Moringa, Roselle and Lemon grass was more appealing than herb tea from only Moringa.
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COMPARATIVE STUDY OF BIOGAS PRODUCTION FROM COW DUNG, CHICKEN DROPPINGS AND CYMBOPOGON CITRATUS AS ALTERNATIVE ENERGY SOURCES IN NIGERIA
This study was carried out to produce biogas from Cow dung, Chicken droppings and Cymbopogon citratus as well as the respective co-digestion of Cow dung and Chicken droppings with Cymbopogon citratus. 25 litre digesters and gas collection systems were designed and fabricated using locally available materials. The digesters were used to digest cow dung, chicken droppings and Cymbopogon citratus respectively as single substrates as well as to co-digest cow dung and chicken droppings respectively with Cymbopogon citratus. The respective feed materials were collected locally. They were pre-fermented, digested and analysed in accordance with standard methods. For the single substrates, the total volume of gas produced were 0.191m3 (0.032 m3/kg), 0.211m3 (0.035m3/kg) and 0.125 m3 (0.021 m3/kg) (before scrubbing) and 0.125m3 (0.021m3/kg), 0.130m3 (0.022 m3/kg), 0.090 m3 (0.015 m3/kg) (after scrubbing) for cow dung, chicken droppings and lemon grass respectively. For the co-digested substrates, Cow dung + Lemon grass produced 0.146m3 (0.024 m3/kg) before scrubbing and 0.100m3 (0.017m3/kg) after scrubbing while Chicken droppings + Lemon grass produced 0.193m3 (0.032 m3/kg) before scrubbing and 0.127m3 (0.0.021m3/kg) after scrubbing. The average ambient temperatures during the study were within the mesophilic range (20-40oC). The pH values were stable and always in the optimal range between 6.5-8.0. The reductions in total solid were 75.3 %, 60.1%, 98.2%, 61.9% and 35% for cow dung, chicken droppings, lemon grass, cow dung + lemon grass and chicken droppings + lemon grass respectively. The total coliform contents of the residue were 2.00 x107 CFU/100ml, 6.00 x 107 CFU/100ml, 1.00 x 107 CFU/100ml and 1.00 x 107 CFU/100ml for cow dung, chicken droppings, cow dung + Lemon grass, and chicken droppings + Lemon grass respectively with 95%, 70%, 95% and 99% reduction in each case. Pathogens such as Salmonella spp and Klebsiella sp. were still present in the residue although E.Coli and Shigella sp. were removed. The estimated methane contents of the gas from cow dung, chicken droppings, Lemon grass, Cow dung + Lemon grass and Chicken droppings + Lemon grass were 65.59%, 61.71%, 71.95%, 68.53% and 66% respectively. The cooking rates for water were 0.079L/min, 0.070L/min, 0.067L/min, 0.064L/min and 0.060L/min for unscrubbed lemon grass, cow dung + lemon grass, chicken droppings + lemon grass, cow dung and chicken droppings respectively while those for scrubbed lemon grass, cow dung + lemongrass, chicken droppings + lemon grass, cow dung and chicken droppings were 0.12L/min, 0.10L/min, 0.091L/min, 0.085L/min and 0.079L/min respectively. The rice cooking rates were 0.0038kg/min, 0.0034kg/min, 0.0033kg/min, 0.0031kg/min, and 0.0030kg/min for unscrubbed lemon grass, cow dung+ lemongrass, chicken droppings + lemon grass, cow dung and chicken droppings respectively while those for scrubbed lemon grass, cow dung+ lemongrass, chicken droppings + lemon grass, cow dung and chicken droppings were 0.0055kg/min, 0.0048kg/min, 0.0045kg/min, 0.0041kg/min and 0.0039kg/min respectively.
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