Physical, chemical and sensory attributes were
examined on canned green beans (Oregon 1604) of sieve sizes
3 & 4 and 5 & 6 after one and three months of storage at
room temperature (RT). The green beans subjected to
different pre-blanch conditions in water (T1t1: 160°F - 30
min.; T1t2: 160°F - 90 min.; T2t1: 200°F - 30 min.; T2t2:
200°F - 90 min.) were blanched in a steam exhaust line for
2 min. and 50 sec. at 208-210°F to inactivate the enzymes
still active. The control (T3: direct blanch) was
significantly different from the others. Heat treatment
prior to blanching and the other variables (sieve size and
storage) had highly significant effects on all quality
attributes of canned green beans. The pH was significantly
lowered by pre-blanch and by canned storage. This
decrease was considerably faster for sieve 5 & 6 than for
sieve 3 & 4. The lowest pH value was obtained for T1t2 and corresponded to the most firm and most green canned green
beans. The effects of increasing sieve size, temperature
and time of pre-blanch were significant (P ≤ 0.01) on
slough. The decrease of sloughing during storage was not
found to be significant. The resistance to compression
and shear was significantly increased by the lower
temperature of pre-blanch (160°F), which activated pectin
methylesterase (PME), and also by a longer canned storage
time (3 months). Larger green bean sieve size and
increasing temperatures, lowered the resistance to
compression and shear which was negatively correlated with
pH and slough. EDTA-soluble pectins (EDTA-SP) which were
significantly higher with lower temperature of pre-blanch
and in smaller sieve size were not affected by storage at
RT. EDTA-SP, highly positively correlated to resistance to
compression and shear, showed a negative relationship with
pH and slough. However, water-soluble pectin (WSP)
increased with larger sieve size, longer storage and higher
temperature, and declined when time of pre-blanch
increased. Sensory attributes for texture, appearance,
color and flavor had a high degree of correlation with
chemical and physical parameters. The judges were more
able to distinguish changes introduced by pre-blanch
treatments than those related to different stages of
storage or different sieve sizes. There was a loss of
green color and an increase of yellow and brown color
associated with heat treatments. While treatment T1t2 (160°F-90 min.) had the highest retention of green color,
the control (T3) displayed the highest loss. Also,
firmness and brine clarity of the canned green beans were
improved with pre-blanch at the lower temperature (160°F). / Graduation date: 1985
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28165 |
| Date | 19 December 1984 |
| Creators | Boni, Magloire C. |
| Contributors | Varseveld, George W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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