FI106359B - Use of treated grain as an antioxidant - Google Patents

Description

! 106359 Use of treated cereals as antioxidants

Field of the Invention

The present invention relates to the use of cereals treated in a particular manner as an antioxidant. More specifically, the grain is treated to prevent oxidation.

Background

Fat rancidity is an undesirable phenomenon, especially in the food sector. When lipids in food become rancid, they form hydro-10 peroxides, which are susceptible to further reaction and, when degraded, form, for example, aldehydes, ketones, acids and alcohols. As a result, unpleasant odors and flavors are created and, on the other hand, the nutritional, quality and commercial value of the food is reduced.

Fat rancidity typically begins when hydrolytic enzymes release fatty acids from which unsaturated free fatty acids are sensitive to oxidation. Cereals are naturally very high in both mono- and polyunsaturated fatty acids. Oxidized fat compounds continue to react and break down, causing odor and ma-image errors in cereal products. Powdered cereals are particularly susceptible to rancidity and especially when in contact with water. Therefore, in almost all cereal water processes, fat rancidity is one of the most important problems.

Wherever possible, lipid rancidity is sought, for example, by adding antioxidants, inhibiting oxygen delivery, and / or regulating water activity (ACS Symposium Series 500: Lipid Oxidation in; 25 Foods, eds. Allen J. St. Angelo, American Chemical Society, Washington, DC, 1992). Lipoxygenases in cereals are known to accelerate fat oxidation. Their activity may be reduced, for example, by heat treatment or by addition of propionic acid (Ceumern, S. & Hartfield W., 1984, Fette Seiten Anstrichmittel, 86. Jahrgang, No. 5, pp. 204-208. On the other hand, cereals have also been found to contain antioxidants ( Nicolas, J. & Drapron, R., Proc., 7th World Cereal and Bread Congress, Prague, 1982; Iwami, K., et al., 1988, J. Agric., Food Chem.

36, pp. 160-164; and Fretzdorff, B. & Jördens, A., 1986, Lebensm.-Weiss. u.-Tecnol., 19, pp. 437-442; White, P. & Armstrong, L., 1986, JAOCS 63, pp. 525-529; Tian, L. & White, P., 1994, JAOCS 71, pp. 1079-1086; Duve, K. & White, 35 P., 1991, JAOCS 68, pp. 365-370; Onyeneho, S. & Hettiarachchy, N., 1992, J..

Agric. Food Chemistry, 40, pp. 1496-1500).

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The most commonly used antioxidants in the food industry and also in cereal products are butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). They are stable, cheap and effective, but their use has recently decreased due to suspected carcinogenicity. Safer antioxo-5 binders are ascobic acid and tocopherol derivatives, although less effective (Namiki, M., 1990, Critical Reviews in Food Science and Nutrition, 29, (4), pp. 273-300). However, the general trend in the food industry is the desire to dispense with additives and many consumers prefer natural products to which no synthetic substances have been added.

Brief Description of the Invention

It has now been discovered that cereals can be treated to prevent oxidation. The invention thus relates to the use of cereals which have been treated by raising the moisture content of whole cereals to at least 30% moisture and then drying the grains to less than 12% moisture. The invention makes it possible to prevent oxidation of both the cereal's own fats and any other fat added. The treatment described herein also enhances the ability of the grain to inhibit external oxidative activity. In other words, this cereal treatment method enhances the antioxidant effect of the grain. In the method, the grain is rendered antioxidant by raising the moisture level of whole club grains to at least 30% moisture, and then drying the grains to less than 12% moisture.

Thus, the antioxidant treated cereal is made antioxidant by raising the moisture of the whole cereal grains to at least 30% moisture, and then drying the grains to less than 12% moisture. Grain is suitable for use in 25 foods. Particularly processed cereals can be utilized in any process where the oxidation or hydrolysis and oxidation of fats is strong. Such processes include, for example, all treatments in which the cereals are exposed to water, the so-called. cereals water processes. Thus, the cereals treated as described above are suitable for use in the cereal water process.

Further described herein is a product, e.g., a food containing processed cereal. By replacing some of the raw materials in the process with processed cereals, the shelf life of the product can be extended and / or the amount of anti-oxidants used as additives may be reduced. In cereal products, a clear effect is achieved when at least 10% of the cereal is replaced by processed cereal. Processed cereals act as a natural antioxidant in the process. Thus, the processed cereal may be used as an antioxidant. Treated cereal prevents both the grain's own fat and the fat added to the grain from becoming rancid.

DETAILED DESCRIPTION OF THE INVENTION The process described herein involves Liot-5 whole cereal grains in water at a moisture content of at least 30% and drying the moistened grains. The most beneficial effect is achieved by moistening the grains with a moisture content of 45 to 55%. Suitable chemicals such as phosphate or carbonate salts may be added to the soaking water if desired. The soaking time depends on the temperature used, i.e. in the warm water the desired humidity 10 is achieved faster than in the cold. When using room temperature water, the desired humidity is achieved within about 1-2 days. Preferably, the soaking takes about two days. The seeds are not sprouted.

After soaking, the grains are dried to less than 12% moisture and especially to less than 8% moisture. The drying may be carried out either by freeze drying or by heat drying. In heat drying, it is advantageous to start with a lower temperature which is gradually raised during drying, as in the case of malting. For example, drying begins at about 40 ° C and ends at about 80 ° C. Other drying profiles will run as long as the antioxidant capacity is not lost. After drying, the processed cereal 20 can preferably be milled. It is also possible to isolate from the treated cereal a fraction which prevents oxidation. Thus, the isolation of the antioxidant fraction from cereals is also within the scope of the invention.

Cereals treated as described above cause the cereals' own fat or the fat added externally to slow down the oxidation. Even oxidizing activity added up to ul-25 is inhibited. During processing, the grain's own fat remains similar to that of the native grain, i.e., no soaking of the fat occurs during soaking. Otherwise, soaked cereals are suitable for the same uses as unprocessed cereals.

The soaked and dried cereals according to the method can be used either as such or as a grinding or possibly antioxidant fraction. is, after isolation, subjected to various types of processes such as baking, cooking, roasting, etc., i.e. any process in which fat is susceptible to rancidity. Preferably, the processed cereal is ground and used in cereal-water processes such as baking, porridge, ready meals, sausages, etc. The grinding and use of the treated grains in aqueous applications causes the oxidation of the own fat of the flour and other fat added to the cereal. Particularly processed cereals are suitable for processes where the cereals are exposed to water prior to heating and the inactivating forces of the enzymes.

The method described herein is applicable to all common cereal species, and also improves the ability of already-malted grain to prevent fat oxidation. In particular, the method is suitable for treating barley, malt, wheat, rye and oats.

The cereal treatment method, in which the grain is first soaked and then dried, increases the ability of the grain to slow down oxidation. It is also able to protect the outside fat added from oxidation. It appears that the antioxidant effect achieved by the process is at least partly due to changes in grain constituents during processing such that the treated grain protects and stabilizes fats.

According to the method, the property obtained by soaking is stable.

15 The antioxidant capacity of fats is maintained or improved by storing grains prepared according to the method under normal storage conditions.

The grain to be treated is preferably barley, malt, wheat, rye or oats.

The treated cereal may be in the form of powder, whole grains or an antioxidant fraction isolated from the treated cereal.

The product containing the above-mentioned processed cereal is preferably a food product such as ready-to-eat food or sausage or, in particular, a cereal preparation, such as breads, flour, cereals, breakfast cereals, porridge, etc.

Treated cereals can also be used as an antioxidant, for example to prevent oxidation of meat or fish.

The invention is further illustrated by the following non-limiting embodiments. The experiments investigated how the apparent oxidative activity of various cereals changes during soaking and storage and why. The experiments also investigated whether the ability of cereals to inhibit the oxidation reaction during soaking and storage.

Example 1

Six different cereal materials were used, namely barley, malt, wheat, rye, oats, and oats in shell. First, the wetting of the cereals was observed during soaking. The cereal grains were mixed with plenty of water at room temperature for 30 sec to 48 h. The grains were shaken in a sieve with loose water and their moisture was measured. The results are shown in Table 1.

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table 1

Moisture grains during soaking

Grain- Tests- 30 sec 3 h 24 h 48 h d (48 h-30s) material free% units _grain_

Barley 12% 27% 37% 43% 49% 22%

Mallas 5% 24% 36% 53% 61% 37%

Wheat 12% 22% 36% 42% 49% 27%

Rye 9% 24% 38% 47% 44% 20%

Oats 11% 22% 48% 48% 55% 33%

Shellless 11% 23% 37% 45% 52% 29% oats 5 Example 2

About 100 g of the grains were soaked in about 300 ml of room temperature water. Water was added as necessary so that the grains were always covered with water. After soaking for 2 days, the grains were dried either in a freeze dryer or in an oven. The furnace temperature was initially 40-50 ° C and then the temperature was gradually increased to 60-70 ° C and then to about 80 ° C. The drying took a total of about 22 to 24 hours. The moisture content of the dried grains was about 5%.

After drying, the grains were ground. 100 mg of milled cereal was slurried in neutral (pH 7.0) Na phosphate buffer (50 mM), followed by addition of about 8.6 mg of linoleic acid in a Tvveen emulsion. The mixtures were allowed to react for 15 min, after which the cereal material was separated from the buffer by centrifugation. The material was subsequently washed with buffer and then extracted with chloroform-methanol (100: 1). Linoleic acid content was determined from various steps of the treatment (Suutari, M. et al., 1990, J. Gen. Micobiol., 136, pp. 1469-1474) to determine to which fraction the added fat was transported. The same treatment was performed in parallel without adding linoleic acid-tween emulsion (Sample 0). The results are shown in Table 2. In the results shown, the linoleic acid concentrations obtained from the 0 samples were subtracted to distinguish the migration of the added acid from that of the sample linoleic acid itself. The amount of oxidized fat is calculated by subtracting the total linoleic acid content of the fractions from the added 25 fat amounts.

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Table 2

Amount of oxidized fat in various cereal-water mixtures Unprocessed cereals Soaked and freeze-dried

Barley 6.6 mg 3.5 mg 3.3 mg

Mallas 0.5 mg 0 mg 0 mg

Wheat 3.5 mg 2.6 mg 2.3 mg

Oats 2.1 mg 0.3 mg 0.6 mg

Rye_5.1 mg_3.5 mg_3.3 mg_ 5 Fat oxidation was significantly reduced by the addition of soaked and dried cereals instead of unprocessed cereals.

Example 3

Cereal grains were soaked and dried as in Example 2. Samples were ground immediately after drying and measured for linoleic acid oxidation by 10 oxygen consumption without extraction, i.e. directly from a mixture of 100 mg of ground cereal, 7 ml of the above phosphate buffer and 0.86 mg of linoleic acid as described. Kaukovirta, N. et al., 1993, J. Inst. Brew., 99, pp. 395-403. The results are shown in Table 3. The activity unit (U) corresponds to the activity consuming 1 μmol at 02 min under the assay conditions used.

Table 3

Oxidizing activity in 100 mg of fresh sample Untreated Soaked / frozen Steeped / HG Hot.

_grain_

Barley 1200 U 1000 U 570 U

Mall 50 U 80 U <10 U

Wheat 630 U 510 U 340 U

Rye 290 U 240 U 110 U

Oat 50 U 40 U 20 U

Shelled Oats_100 U_80 U_40 U_ 20 7 106359

The ability of the cereals to oxidize fat was significantly reduced when the grains were soaked as in Example 2.

Example 4

The cereal grains were soaked and dried as in Example 2. After three weeks and 5 months of storage, the samples were ground and their linoleic acid oxidizing activity was measured by oxygen consumption as in Example 3. The results are shown in Tables 4 and 5.

Table 4 10 Oxidizing Activity in 100 mg Samples Preserved for 3 weeks Untreated Soaked / Cold Steeped / HG Hot.

_grain_

Barley 1100U 690 U 620 U

Mall 60 U 40 U <10 U

Wheat 510 U 240 U 200 U

Rye 220 U 110 U 20 U

Kaura 30 U 20 U <10 U

Shelled oats_40 U_30 U_20 U_

Table 5 15 Oxidizing Activity in 100 mg Samples Preserved for 3 Months • ~ II .. - I - - Untreated Soaked / Cold. Steeped / HG Hot.

_grain__

Barley 1100 U 580 U 650 U

Mall 80 U 30 U <10 U

Wheat 600 U 340 U 370 U

Rye 330 U 70 U 70 U

Kaura 70 U 20 U <20 U

Shelled Oats_70 U_30 U_50 U_

The reduced ability of the cereals to oxidize fat was maintained when the samples taken according to Example 3 20 were stored for 3 weeks or 3 months.

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Example 5

Cereal grains were soaked and dried as in Example 2. Samples were ground immediately, 3 weeks or 3 months after drying, and their effect on extracellular oxidative activity was measured by total oxygen consumption as above. Soybean lipoxygenase activity was used as the external oxidant. 30 mg of cereal samples were used in the assays. The results are shown in Tables 6, 7 and 8.

Table 6 10 Effect of soaking and drying on the ability of cereals to inhibit external oxidative activity. Approximately 600 U of external oxidant was added in the measurement.

Untreated Soaked and packed Soaked and oven-dried _grain_grain dried cereal_

Barley 490 U 370 U 210 U

Wheat 360 U 220 U 160 U

Rye_180 U_150 U_140 U

15

Table 7

Effect of soaking and drying on the ability of cereals to inhibit external oxidative activity. Approximately 600 U. of external oxidant was added for measurement. Samples were stored for 3 weeks after drying.

20 _ Unprocessed Soaked and packed Soaked and oven-dried _grain_grain-dried cereal_

Barley 490 U 390 U 360 U

Wheat 350 U 220 U 110 U

Rye 270 U 210 U 160 U

Kaura_160 U_120 U_110 U

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Table 8

Effect of soaking and drying on the ability of cereals to inhibit external oxidative activity. Approximately 550 U. of external oxidant was added to the measurement. Samples were stored for 3 months after drying.

5 _ Unprocessed Soaked and packed Soaked and oven-dried _grain_grain dried cereal_

Barley 490 U 330 U 360 U

Rye 330 U 270 U 240 U

Kaura_230 U_190 U_210 U

The results show that the ability of the cereals to inhibit external oxidative activity increased as samples were soaked and dried according to Example 2.

K

Claims (8)

1. Use of grain treated by raising the moisture content of whole grains to at least 30% moisture, and then drying the grains to a moisture content below 12%, as antioxidant. Use according to claim 1, characterized in that the grain used is treated by raising its moisture content to 45 - 55% humidity and drying the grains to below 8% humidity. Use according to Claim 1 or 2, characterized in that cereals are used after milling. Use according to claim 1, characterized in that barley, malt, wheat, shrimp or oats are used. Use according to claim 1, characterized in that the cereal is used as an antioxidant in any process where fat can be ruled. Use according to claim 1, characterized in that the grain is used as an antioxidant in food. Use according to claim 6, characterized in that the grain is used as an antioxidant in a grain-water process. Use according to claim 7, characterized in that the grain is used as an antioxidant in baking, in porridge, ready-made food or sausage. «I