Effects of Temperature and Holding Time During Pre-blanch on PH, Pectic Substances and Quality Characteristics of Canned Green Beans PDF Download
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Author: Magloire C. Boni Publisher: ISBN: Category : Canned beans Languages : en Pages : 250
Book Description
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 [less than or equal to] 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).
Author: Magloire C. Boni Publisher: ISBN: Category : Canned beans Languages : en Pages : 250
Book Description
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 [less than or equal to] 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).
Author: Ray Wesley Farrier Publisher: ISBN: Category : Beans, Frozen Languages : en Pages : 148
Book Description
A quality problem that frequently occurs with frozen green beans is the sloughing of the skin (epidermal tissues) of the cooked, ready-to- serve bean pods. It was found that by giving the beans a pre-blanch (relatively mild heat treatment) prior to the blanch treatment normally used for frozen green beans, on cooking, sloughing was markedly reduced, and furthermore, the bean pods were firmer. As an additional heat treatment was involved, over and above what is now used for commercial packs of frozen green beans, it was of interest to know the extent to which the color of the beans was affected. Also of interest was the effect of storage at 0°F for four months on the color of the beans. The color changes in the dual and single blanched green beans were evaluated by two methods: (1) a physical analysis of the light reflected from the beans (Hunter Color and Color Difference Meter) and, (2) a physical analysis of the light absorbing properties of the pigments extracted from the beans and subsequent calculation of the per cent conversion of chlorophyll to pheophytin. Texture (firmness), as indicated by resistance to shear, was measured by a modified Kramer Shear Press. A mechanical device was used to determine the amount of sloughing of the skins of the bean pods. After a statistical analysis of the data collected in the experiment, the following conclusions were drawn: 1. The firmness of the cooked, dual and single blanched, frozen green beans, as measured by the shear press, was found to be highly significantly negatively correlated with sloughing of the skins. 2. There was no change in lightness or darkness of the color of single or dual blanched beans over storage at 0°F for four months. The Hunter "--A [subscript L]/b [subscript L]" index of color noted a significant change in hue from green towards yellow of the single and dual blanched beans. The conversion of chlorophyll to pheophytin was not significant over storage. 3. The color of those beans receiving the 200°F - 150 second final blanch (single blanch) was the same as the color of those beans receiving the 210°F - 105 second final blanch (single blanch). 4. As the time and temperature of the pre-blanch increased, there was a corresponding increase in the amount of chlorophyll converted to pheophytin, and a change in the visual color of the beans from green towards yellow. The effect of variations of time of preblanch was much greater on the color of the dual blanched beans than the effect of variations of temperature of pre-blanch. 5. As the time and temperature of the pre-blanch increased, the texture (firmness) of the cooked dual blanched beans increased. The 200°F - 150 second final blanch resulted in beans that were firmer than beans receiving the 210°F - 105 second final blanch, 6. A pre-blanch at 170°F for 30 seconds followed by a final blanch at 200°F for 150 seconds was found to result in beans that were similar in color, yet firmer in texture (less sloughing of the skins) than the single blanched beans.
Author: Jeremiah Publisher: CRC Press ISBN: 1351447084 Category : Technology & Engineering Languages : en Pages : 535
Book Description
This work presents a comprehensive overview of existing knowledge regarding the influence of freezing, frozen storage and thawing of specific food-stuffs. It delineates how freezing processes alter the colour, appearance, palatability, nutritional value, intrinsic chemical reactions, microbiological safety and consumer acceptance of foods. The fundamental concepts upon which food-freezing technologies are based, are reviewed.
Author: Magloire C. Boni
Author: Magloire C. Boni
Author: Ting-Feng Michael Liu
Author: Gale Richard Ammerman
Author: James Michael Carr
Author: Ramanathan Santhanagopalan
Author: Ray Wesley Farrier
Author: Anna Mae Brenner
Author: Beulah Fay Hattox
Author: Tony V. Johnston
Author: Jeremiah