Page 76 - FoodFocusThailand No.223 October 2024

STRATEGIC R & D

Approaches to Reducing Beany Flavor of Lipoxygenase. Antioxidants like BHA, BHQ, tocopherols,
in Legume Flour and others.
The removal of the beany flavor in flour derived from legumes Approach 3: Creating pH conditions that are unfavorable
can be achieved through the use of heat and chemicals to for the activity of the Lipoxygenase enzyme. It has been
inhibit the activity of the lipoxygenase enzyme, including reported that Lipoxygenase functions optimally in a pH range
removing fat from the flour. However, legume flour that has of 6.5-9, which is neutral to alkaline. Therefore, adjusting the
undergone a deodorization process should be subjected to pH to an acidic condition (pH below 6.5) may result in the
quality testing in various aspects to confirm that the method denaturation of the Lipoxygenase enzyme. In practice, this
used is effective and that the flour can still be utilized. The can be done by adjusting the flour to an acidic condition as a
approaches to reducing the beany flavor in flour are as method to inhibit the activity of the Lipoxygenase enzyme.
follows: 3. Fat Removal from Flour
1. Inhibition of Lipoxygenase Enzyme Activity Fat removal reduces the amount of precursors that cause
by Heat beany flavors. This can be achieved by extracting the fat from
Lipoxygenase is a protein that undergoes denaturation the flour using solvents, possibly through prolonged soaking
when exposed to heat. The level of heat used to inhibit the followed by centrifugation. The residue from sedimentation is
enzyme’s activity is at temperatures of 60°C and above, then dried. The selection of an appropriate solvent is a key
requiring conditions that ensure thorough heat exposure. factor affecting the efficiency of fat extraction.
Common methods used include: (1) Flour heating – Another approach to fat removal is using mixed solvents.
applying heat directly to the flour by placing it in an oven or For example, improving the beany flavor in bambara groundnut
immersing it in a water medium. (2) Seed steaming – heating flour using a combination of two organic solvents, one
the legume seeds by steaming with hot steam, then grinding non-polar solvent such as chloroform, hexane, or diethyl ether,
the seeds into flour. (3) Seed heating – directly heating the and one polar solvent such as methanol or isopropanol ,
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legume seeds before grinding them into flour. showed significant differences in fat removal efficiency
Previous research has studied the heating of low-fat (p<0.05). The combination of chloroform and methanol
soybean flour in a vacuum oven at 90°C for 30 minutes was found to be the most effective in removing fat from
under vacuum pressure . It was found that the heat-treated the flour.
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flour had a Lipoxygenase activity (LOX) of 10.8 x 10³ U/ml,
reduced from 25.1 x 10³ U/ml. Additionally, when soybean
seeds were steamed at 95°C for 1 hour and then dried at
30°C for 48 hours to reduce moisture before being ground
into flour , the resulting soybean flour had an LOX value of More Information Service Info C011
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106 U/g, reduced from 279 U/g. Furthermore, efforts to
improve the bean flavor of fava bean flour by heating the
seeds with a microwave at 950 watts for 1-4 minutes was
found to reduce LOX (Lipoxygenase) activity by approximately เอกสารอ้างอิง / References
Huang, Y., Hua, Y., & Qiu, A. (2006). Soybean protein aggregation
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66% . induced by lipoxygenase catalyzed linoleic acid oxidation. Food
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2. Inhibition of Lipoxygenase Enzyme Activity Research International, 39, 240–249.
with Chemicals 2 Shin, D. J., Kim, W., & Kim, Y. (2013). Physicochemical and
Approach 1: The use of chemicals with chelating sensory properties of soy bread made with germinated, steamed,
properties that facilitate the formation of bonds with iron, and roasted soy flour. Food Chemistry, 141, 517-523.
leading to the stability of complex compounds. Since the 3 Jiang, Z., Pulkkinen, M., Wang, Y., Lampi, A., Stoddard, F. L.,
Lipoxygenase enzyme contains iron within its molecular Salovaar, H., Piironen, V., & Sontag-Strohm, T. (2016). Faba bean
structure, which plays a role in extracting hydrogen atoms flavor and technological property improvement by thermal pre-treat
ments. LWT-Food Science and Technology, 68, 295-305.
from fatty acids and adding oxygen to them, leading to the 4 Kudre, T. G., and Benjakul, S. (2013). Effects of binary organic
formation of hydroperoxides, these hydroperoxides solvents and heating on lipid removal and the reduction of beany
further break down into fatty acid radicals. Using chelating odour in Bambara groundnut (Vigna subterranean) flour. Food
agents helps remove iron from the Lipoxygenase Chemistry, 141, 1390-1397.
structure, thus inhibiting lipoxygenase enzyme activity. Food 5 Achouri, A., Boye, J. and Zamani, Y. (2006). Identification of
additives classified as chelating agents are reported to volatile compounds in soymilk using solid-phase microex
reduce beany flavors, such as EDTA, propyl gallate, citric traction-gas chromatography. Food Chemistry. 99, 759-766.
Baysal, T., & Demirdoven, A. (2007). Lipoxygenase in fruits and
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acid, etc. vegetables: A review. Enzyme and Microbial Technology, 40,
Approach 2: Using antioxidants to bind with free 491-496.
radicals that would otherwise lead to the formation of 7 Maestri, D. M., Labuckas, D. O., & Guzman, C. A. (2000). Chemical
hydroperoxides. Since the Lipoxygenase enzyme can and physical characteristics of a soybean beverage with improved
trigger the oxidation of polyunsaturated fatty acids and flavor by addition of ethylenediaminetetraacetic acid. Grasesy
hydroperoxides, using antioxidants can inhibit the activity Aceites, 51(5), 316-319.

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