Thesis (MTech (Food technology))--Cape Technikon, Cape Town,1998 / To establish the optimum pasteurisation procedure, the
effects of sous-vide heat processing on the pH, ascorbic
acid and sensory aspects of broccoli (Brassica oleracea var.
Italica) were studied.
Broccoli florets were blanched using steam and
ammonia(NH3)-steam, chilled to <2°C in ice water at O°C,
and vacuum packaged. Sous-vide processing proceeded
immediately at pasteurisation temperatures 73°, 76°, 79°,
82° and 85°C to a p~ = 100. Directly afterwards, the pH of
the processed sous-vide broccoli was measured and
percentage L-ascorbic acid loss calculated, by comparing
sous-vide broccoli with unprocessed controls from the same
broccoli head. Objective colour measurements were made
using CIELAB L*, a* and b* co-ordinates. Consumer
acceptance was tested using paired preference analysis.
The same analyses were repeated after storage at 2° - 4°C
for 21 days.
Suitable statistical analyses showed significantly higher
(P<0.05) pH-values in the case of NHrsteam-blanched
broccoli, with the result that the ascorbic acid retention of
NH3-steam broccoli was significantly lower (P<0.05) than
that of steam blanched broccoli. Higher pasteurisation
temperatures, and resulting shorter heat processing times,
ii
showed a significant reduction (P<O.05) in ascorbic acid
losses.
NHa-steam blanched broccoli was significantly (P<O.05)
greener after pasteurisation than steam-blanched broccoli.
Steam blanched broccoli deteriorated further significantly
(P<O.05) towards a more yellow colour during a 21 day
storage period at 2° - 4°C.
Sensory analysis showed a significant consumer preference
(P<O.05) for the greener NHa-steam- blanched broccoli but
showed a significant preference (P<O.05) for the texture of
steam blanched broccoli. No significant (P>O.05) taste
preference was detected for broccoli from either blanching
method.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/823 |
| Date | January 1998 |
| Creators | Vlok, Nicolaas Hugo |
| Contributors | Venter, I., Mks, Rautenbach, Fanie, Nicolaas Hl, Benade, Spinnie, Prprocessing |
| Publisher | Cape Technikon |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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