Spring 2002 Issue — Lupine Protein: A Functional and Healthy Ingredient

Stefan Lander Dipl.Eng J. Rettenmaier & Söhne GmbH + Co. Stefan Lander studied Food Technology, and is Product Manager in the Food Division at J. Rettenmaier & Söhne GmbH + Co., D-73494, Rosenberg.

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The days in which lupine and lupine products had to hide in the shadows are finally over. Lupine protein takes a step ahead and is now a valuable food ingredient with unique properties. It is no longer just a hot tip for the use in meat and milk products or in baked goods.

The white lupine was already being cultivated in ancient Egypt, Greece and by the Romans. The most famous physician of antiquity, Hippocrates (460 B.C.) praised these plants for their good digestibility. In other countries of the Mediterranean region, the cooked, leached seeds were consumed salted or in sauces. The original lupine varieties contained a group of various alkaloids. In 1927 the German botanists Bauer and Sengbusch successfully cultivated a sweet variety that was also low in alkaloids smoothing the way for lupine products' use in food. The content of this bitter constituent has been reduced to between 0.0 and 0.004 % in modern alkaloid-free sweet lupine varieties.

Extraction of Vitaprot® lupine protein

After the removal of the husks, primarily fractions of globulins are extracted using aqueous extraction. These can be separated analytically into five further subunits. Table 1 shows the composition of the lupine protein concentrate. Low extraction temperatures without the need for chemical solvents are used as opposed to the extraction process used with soy beans. Because there is no heating step, the protein is not denatured and it retains its natural properties. This is especially important in view of the technological properties such as solubility and emulsifying capability.

Nutritional physiological properties of the lupine protein

Food allergies are widespread and unfortunately are increasing. In most cases defensive reactions of the immune system against proteins are present caused by an incomplete decomposition of the food proteins into amino acids. A study was done to determine the eventual increased allergy risk when consuming lupine seeds and their derivatives by the scientists Feldmann and Gross from the Institute for Human Nutrition and Food Information at the University of Kiel together with the German Association for Technical Co-operation (FTZ) in Eschborn. This study was carried out in Peru. The study which took place over several years could not determine any increased allergy risk.

Lupine seeds contain by nature 35 to 45% high quality protein which has all the essential amino acids. Table 2 shows this composition.

Legal classification of Vitaprot® lupine protein

Modern lupine products made from the sweet lupine varieties have extremely low amounts of alkaloids. In England the Advisory Committee on Novel Foods and Processes (ACNFP) studied the issue of the legal food status in depth and determined that lupine products can be considered as safe for consumption when their alkaloid content does not exceed 200 mg/kg. Because as mentioned at the beginning of this article, lupine products were already being used 3000 years before in the Mediterranean region, comparable concentrates or extracts used today are not considered to be new types of products as defined by the EU Decree No. 258/97 (Novel Food Decree).

Lupine is not genetically-modified and thus it is possible to build an important foundation of trust for the consumer who is ever more sensitive to this issue especially with the continuing discussions about soy bean products.

Lupine protein in cooked sausage

In order to study the positive properties of Vitaprot® lupine protein, tests were carried out in cooperation with the Federal Research Institution for Meat Research in Kulmbach/Germany to obtain comparable values for products which were used in similar ways. The standard formula represented in Table 3 was used. As reference batches one control batch with and one without phosphate were designated. For the testing a total of five batches were manufactured with the following ingredients:

1. Control batch without phosphate
2. Control batch with phosphate
3. Batch with 2% lupine protein
4. Batch with 2% sodium caseinate
5. Batch with 2% a 50:50 mixture of lupine protein and powdered cellulose (fibre length 200 µm)

Testing procedure

The testing procedure was as follows:

1. The meat and fatty tissue (2%) were separately pre-minced and each mixed thoroughly.
2. The cooled meat was pre-chopped then salt was added and if applicable, the phosphate was added. Finally the ice was added gradually. After further chopping, the fatty tissue as well as the dry ingredients were added.
3. The meat mixture was placed into casings, 90 mm caliber, and in cans, 73X58 mm.
4. The sausages were reddened for 30 min at 50°C and heated at 75°C for 90 min then cooled down to 20°C core temperature in a water bath. The cans were sterilized in an autoclave for 70 min at 110°C.
5. The end products were assessed visually and sensorially. In addition colour measurements were done using the Hunter Lab Colour Measuring Device Colour Quest, firmness was measured with the Instron 1140 and the gel depositing was also evaluated.

Results

The processing of the Vitaprot® lupine protein as well as the mixtures using lupine protein and powdered cellulose were trouble-free and showed no peculiarities when compared with the other powdered additives. The assessment of the products took place after 12 days of cold storage. As references, the two control batches were used one with and one without phosphate. The sensory assessment showed no immediate influence from the lupine protein. When batches 4 and 5 were compared directly, no differences could be determined. A significant increase in firmness in the products with lupine protein as opposed to the control products without phosphate was determined. The direct visual comparison of batches 3, 4 and 5 showed the greatest similarities between the comparison pair 4 and 5.

Table 4 shows the analytical results of the end products.

One of the main criteria here is the depositing of gel, important especially in canned goods and also in products with a large caliber. The lupine protein's performance in this parameter is particularly obvious. When compared to the products without phosphate (Batch 1) or with caseinate (Batch 4), Batch 3 (with lupine protein) showed here a much higher retention capacity. Fig 1 illustrates this fact and also clearly points out that with Batch 1 twice as much gel was deposited as in Batch 3!

Additionally the measurements of texture (texture-profile-analysis, sample height 10 mm, diameter 12.3 mm, T=5°C) demonstrated that with all products added, there was a significant increase in the breaking resistance and hardness than in the batch without phosphate. Fig 2 illustrates this. The results of Batches 3 and 4 with the standard deviation considered, are overlapping and can be regarded as being of equal value. During the colour measurement the L* value (brightness), the b* value (yellowish shade) and the a* value (reddish shade) were recorded. There were no observable, significant deviations in these parameters, only a light reddish-yellow shifting in Batch 3 when compared to Batch 4. Batch 5 showed almost the identical values as in Batch 4 as already observed during the visual examination.

Fig 1. Gel depositing (%) of the individual batches.

Fig 2. Breaking resistance (N) of the individual batches.

Conclusion

The results show how Vitaprot® lupine protein can be used in sausage products as a nutritional physiologically valuable protein combined with interesting technological effects.

Lupine protein will in the future be the ingredient of choice not only in meat products but in many other applications as well due particularly to its technological effects and, when compared with caseinate, a much lower price.

An additional economical and technological advantage can be achieved through the use of mixtures as in the example presented with powdered cellulose. Even 1:1 mixtures with caseinate are conceivable in order to take advantage of the synergistic effects.

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