Judul: Identification of aroma profiles two pineapple varieties and their new genotype using gas chromatography-mass spectrometry and gas chromatography-olfactometry and sensory test
Abstrak: Two varieties of pineapples, Mahkota Bogor, Delika Subang and their new genotype (Pasir Kuda), were freshly extracted using liquid-liquid extraction and solid phase microextraction (SPME). The aroma compounds of the three samples were analyzed by GC-MS and GC-olfactometry using nasal impact frequency (NIF) method. A total of 14 odor-active compounds were associated with the aroma of pineapple. Methyl 2-methyl butanoate and ethyl 2-methyl butanoate with very high intensity were found to be responsible for the pineapple fruity sweet odor. Other odorants including methyl hexanoate, ethyl hexanoate, methyl octanoate, methyl 3-(methylthio) propanoate, 2,5-dimethyl-4-methoxy-3(2H)- furanone, δ-hexalactone, γ-octalactone, 2,5-dimethyl-4-hydroxy-3(2H)-furanone and δ-decalactone contribute to the overall aroma of pineapple. The main differences between the aroma of Mahkota Bogor, Pasir Kuda and Delika Subang could be attributed to the olfactory attributes (fruity, sweet, caramel, pineapplelike, coconut) which were perceived by most of the panelist in the Mahkota Bogor and Pasir Kuda but were not detected in the Delika Subang samples. This work is a prerequisite for effective selection of pineapple genotypes with optimal aroma profiles for high consumer acceptance.
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Judul: Genetic diversity analisis on pineapple (Ananas comosus (L.) Merr.) by random amplified polymrphic dna (RAPD)
Abstrak: Pineapple is belong to the Bromeliaceae, a large family of American tropics (only one species originated from Africa) which has 45 genera and 2 000 species. Out of six species of pineapple, Ananas comosus (L.) Merr. is the only species grown commercially for its fruit (Nakasone and Paull, 1998). To date, world cultivation just based on six cultivars, i.e., Cayenne, Queen, Singapore Spanish, Red Spanish, Abacaxi and Perolera, while the first three have been the genetic base of distribution from the original area. In Indonesia, cultivars that recommended by Department of Agriculture are only Queen (Bogor pineapple and Palembang pineapple) for fresh fruit and Cayenne (Smooth or Lisse) for processing uses and assumed to have low genetic variability. In this study, 17 accessions of pineapple (Ananas comosus (L.) Merr.) were evaluated for their morphological performance and subjected to analysis of Random Amplified Polymorphic DNA (RAPD). Eight morphological characters of the accessions were measured to examine their morphological relationship. For RAPD analysis, thirteen primers of 10-mers were used to amplify the genomic DNA of the pineapple accessions. Out of them, three random primers yielded monomorphic products while the remaining amplified a total of 20 (87%) fragments, all of which were polymorphic, with an average of 1.77 fragments per primer. A dendogram based on UPGMA-link method and principal component analysis (PCA) plots were examined the clustering pattern and distribution of the accessions, both for morphological characters and amplification products. As the result, RAPD analysis showed higher coefficient of similarity between pineapple accessions tested rather than morphological's, which may indicate the high environmental influence on the morphological performance. This study was demonstrated that RAPD analysis was able to detect genetic similarity among accessions in one species, eventhough among all primers used, there was no single primer could distinguish between Queen and Smooth Cayenne group of pineapple tested. ...
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Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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