Effect of Irradiation and Storage on the Physico-chemical Properties of Tomato (Solanum lycopersicon L.) Powder under Solar and Freeze-Dried Conditions in Ghana

A study was conducted to assess the effect of irradiation and storage on the physico-chemical properties of tomato (Solanum lycopersicon L.) powder under solar dried and freeze-dried conditions in Ghana.  Forty kilogrammes (40 kg) of tomato fruits were obtained for the study. The fruits were solar and freeze dried and tomato powder obtained from them. These were exposed to gamma radiation from 1-3 kGy, with 0 kGy as control. The parameters investigated in the study for the two-month period include; moisture content, total soluble solids, total titratable acidity, pH and colour.  The pH of the samples ranged from 4.02 to 6.18, moisture content from 12.55% to 23.47%, total titratable acidity from 0.11% to 0.99%, total soluble solids from 4.80% to 5.06%, L*(colour) from 32.71 to 36.97, a* (colour) from 6.69 to 22.02 and b*(colour) from 14.38 to 22.91. Gamma radiation did not affect moisture content of the samples, total soluble solids, total titratable acidity and pH (p>0.05). Gamma irradiation affected the colour of the samples significantly (p<0.05). Key words: irradiation, storage, moisture content, pH, total soluble solids, solar dried, freeze dried, Akoma, month

Callus Induction and Plant Regeneration from Dehusked Mature Seeds of Three Accessions of African Rice (Oryza glaberrima Steud.)

Three accessions of African rice (Oryza glaberrima Steud.), Guame, N/4 and SARI 1 were assessed for their callus induction and plant regeneration ability from mature dehusked seeds on Murashige and Skoog (MS), (1962) basal medium supplemented with varying concentrations of plant growth regulators. Mature dehusked seeds were inoculated onto callus induction medium consisting of MS supplemented with varying concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) in the range 0.0-6.0mg/l. All tested accessions exhibited highest callus induction at 4.0 mg/l 2,4-D. Callus induction frequency was significantly (p≤0.05) different among the accessions, as well as among the 2,4-D levels  tested. Calli obtained were also sub-cultured on MS medium, further supplemented with varying concentrations (0.0-2.5 mg/l) of 6-benzylaminopurine (BAP). The highest regeneration frequency was obtained on medium containing 2.0 mg/1 BAP.  However, callus induced on 3.0 mg/l 2,4-D and further sub-cultured on  2.0 mg/l BAP gave the best response in terms of shoot proliferation, shoot growth and root development; therefore, considered to be the optimum concentrations for callus induction and plant regeneration respectively. Plantlet regeneration was achieved only in the accession N/4 while Guame and SARI 1 exhibited poor regeneration response. Among the three African rice accessions evaluated, N/4 was the most promising in terms of callus induction frequency and regeneration ability. Keywords: Oryza glaberrima, callus induction, plantlet regeneration, shoot proliferation, 2, 4-dichlorophenoxyacetic acid, 6-benzylaminopurine