Page 338 Table 4.-Kernel Yields, Oil Content and Oil Yields of the more important
Groundnut Varieties, Kongwa, 1947-48 Season
Variety
Habit
Kernel yield (lbs. per acre)
Oil content
(per cent. of
Oil yield (lbs. per acre)
kernels)
Spanish Bunch...
upright
1,048
48.3
506
Natal Common
upright
1,170
47.8
559
Valencia*
bushy upright
45-4
•
Manyema
bushy upright
1,199
45.9
539
Virginia Bunch
open upright
1,268
40.3
511
Runner and semi-runner
types...
1,267
41.4
524
The higher kernel yields of the runner types in this experiment are roughly balanced by their lower oil content, so that average oil production per acre is similar for the various types.
Additional results for other varieties will be found in Section 14.
Since the less upright varieties are in general adapted to longer seasons than are experienced at Kongwa, it is not unlikely that the lower oil content of their kernels, compared with those of the shorter season upright types, may be due to the higher proportion of immature nuts of lower oil content occurring in the produce at harvest. This matter is to be investigated further.
Effect of heat treatment on free fatty acid content of groundnut and sunflower oil
It was suggested during the season that a significant part of the free fatty acid content of the oil from commercial shipments of groundnuts or sunflowers reach- ing the U.K. might arise from the action of fat-splitting enzymes. (lipases) present in the cells of the groundnut kernels or sunflower seeds. Should this be the case, it should be possible to secure reductions in free fatty acid content by heating the seeds or kernels before shipment sufficiently to inactivate the lipases.
This matter was examined by Professor T. P. Hilditch, D.Sc., F.R.S., of the Department of Industrial Chemistry, Liverpool University. Samples of ground- nuts were taken from freshly-dug plants and from sun-cured plants, and heat treatment (70° C.) was applied to both shelled and unshelled portions of the sun-cured sample. These portions were further sub-divided and parts of each were sent to England by air freight and by parcel post to provide a contrast of transit conditions.
The results showed that in all cases the oils were uniformly light in colour, with very low free fatty acid contents, and of very high quality. It may be concluded that lipase action is of no importance provided the groundnuts are carefully harvested, well dried and shelled and shipped in such a way as to avoid mechanical damage. This last condition is difficult or impossible to realise in large scale practice; but it is probably of great importance since mechanical damage will not only liberate any fat-splitting enzymes which are present in the nuts, but will also permit attack by moulds and insects leading to the development of free fatty acid. Further, even if fat-splitting enzymes within the seeds were eliminated by heat treatment, mould and insects attack would still follow mechanical damage, so that it seems unlikely that heat treatment would be of any value in reducing free fatty acid content of the expressed oil.
• All Valencia plots were badly damaged by wild pig, and yield figures are accordingly omitted from this Table.
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