What Is Carob Germ Meal (Seed Protein)?
Carob kernel is not only the source of carob gum. The embryo (germ) part of the kernel, located between the endosperm, is a protein-rich fraction and when ground, a raw material called "carob germ meal" is obtained. This flour occurs as a by-product of carob gum production.
What makes germ flour interesting is that some of the proteins it contains show viscoelastic properties similar to wheat gluten. Researchers have named these proteins "caroubin". In this article, we discuss how germ flour is obtained, its composition, the similarities and differences of caroubin with gluten, and scientific findings on its use in gluten-free products.
Parts of Carob Seed and Germin Location
The carob seed consists of three main parts from outside to inside: the hard and dark seed coat, the endosperm under the shell and the embryo in the center of the seed, that is, the germ. The endosperm is rich in galactomannan and is the raw material of the carob gum (E410). The germ is the part where the new plant will be formed; proteins, fats and minerals are concentrated in its structure.
The purpose of carob gum production is to separate the endosperm as pure as possible. After the shell is peeled, the endosperm and germ are separated from each other. As mentioned in a 2023 study by Siano et al., carob seed germ meal is a by-product left over from the extraction of carob gum used in food, pharmaceutical, and cosmetic applications. Therefore, germ meal is a natural output of gum production, not a separate production line.
This also makes germ meal important for sustainability: A part of the kernel can be converted into a value-added protein source instead of just being used as a by-product.
How is germ meal obtained?
Germin separation depends on the method of peeling the shell of the core. In industry, acid treatment or thermal methods are usually used for debarking; then, by mechanical crushing and screening, the endosperm and germ are separated from each other.
In the 2007 study by Dakia, Wathelet, and Paquot, carob kernel germ flours were obtained by acid treatment or boiling water treatment, and it was shown that the dehulling method can affect the composition of the germ meal. In the research, small decreases in protein and fat content were observed in germ flours obtained with acid. This finding is a reminder that the technical specification of commercial germ meal depends not only on the raw material but also on the process conditions used.
The resulting germ is dried and ground into flour. In addition, protein isolate can be prepared by methods such as alkaline extraction and isoelectric precipitation to obtain proteins in a purer form. In the study of Bengoechea et al., it was reported that an isolate containing 96.5 percent protein was obtained from carob germ flour defatted by this method.
Composition of Germ Flour: Protein, Fat, and Minerals
The prominent feature of germ meal is its high protein content. In the analysis of Dakia et al., the composition of an industrially obtainable carob germ meal (including thin shell and endosperm fragments) was reported as follows:
| Component | Value (Dakia et al., 2007) |
|---|---|
| Humidity | %8,3 |
| Ash | %6,5 |
| Oil (neutral and polar) | %6,6 |
| Crude protein | %54,7 |
| Energy value | 17.5 kJ/g |
In the same study, linoleic acid (44.5 percent) and oleic acid (34.4 percent) were dominant among fatty acids; palmitic (16.2 percent) and stearic acid (3.4 percent) were prominent among saturated fatty acids. It was also reported that essential amino acids were found at "very interesting" levels according to the FAO standard, but their tryptophan content was low.
Bengoechea et al., on the other hand, showed that germ proteins contain high amounts of amino acids such as glutamic acid, aspartic acid and arginine. It is important to note that these values may vary depending on the variety, growing conditions and process; for a commercial product, the certificate of analysis should be taken as a basis.
Germ flour has been examined not only for protein but also for phenolic compounds. In the 2011 study by Custódio et al., it was reported that methanol extracts of germ flour were rich in phenolic compounds and showed antioxidant activity in a laboratory environment. Siano et al. also pointed out that germ flour contains relatively high amounts of apigenin-derived C-glycosides. These findings are at the laboratory level and should not be interpreted as a direct result of human health.
Caroubin: Carob protein similar to gluten
The source of interest in carob germ proteins is that some of them can form a flexible and extensible structure resembling wheat gluten when kneaded with water. According to the 1998 paper by Feillet and Roulland, the existence of a gluten-like substance in carob germ was first suggested by Bienenstock and his colleagues in 1935. Feillet and Roulland confirmed the viscoelastic properties of water-insoluble proteins isolated from the germ by dynamic and static rheological measurements and "caroubin" suggested his name.
In the same study, significant similarities (high glutamic acid content, similar size exclusion chromatography profiles and electrophoresis patterns) and significant differences (high arginine, low cysteine and proline content in caroubin, different carbohydrate composition) were found between caroubin and wheat gluten.
The 2010 study by Smith et al. examined the fractions of germ proteins in more detail. With modified Osborne extraction, it was found that about 32 percent of carob germ meal proteins were albumin and globulin, about 68 percent were glutelin, and no prolamine is detected reported. It has been stated that the glutelin fraction contains high molecular weight polymers linked by disulfide bonds, but the molecular weight distribution of polymeric proteins is lower than that of wheat, which may explain the differences in functionality between the two flours.
This result is important: Although caroubin exhibits "gluten-like" behavior, it is not chemically identical to wheat gluten. The fact that prolamins, one of the main fractions that make up wheat gluten, have not been detected in germ proteins, indicates that caroubin is a different protein system.
Use in Gluten-Free Products: Dough or Fluid Dough?
One of the main technical problems of gluten-free bread production is the absence of the network structure provided by gluten. For this reason, many gluten-free breads are produced from a fluid mixture (batter), not from a kneaded dough. Carob germ proteins attract attention at this point.
In the 2012 study by Smith et al., it was emphasized that gluten-free bakery products can be produced from a real dough instead of a hard fluid dough, thanks to the functional properties of carob germ proteins similar to wheat gluten. In the study, the wheat-free bread formulation consisting of carob germ flour, corn starch, salt, sugar, hydroxypropyl methylcellulose (HPMC) and water was optimized by the response surface method. Optimum formula; It was determined as 7 percent carob germ flour, 93 percent corn starch, 2 percent HPMC and 80 percent water on the basis of flour, and it was reported that a specific volume of approximately 5.6 ml/g was obtained when the fermentation time was optimized.
This study shows that germ flour is not alone; It shows that it is used as a structure-forming component in low proportions together with starch and hydrocolloids. In more recent studies, germ flour is also considered as a fiber-enriching ingredient in gluten-free breads; for example, Jang et al. compared carob seed germ meal with inulin and psyllium husk in 5 and 10 percent ratios in rice flour-based gluten-free bread.
Germ flour has been tested not only in bread, but also in pasta. Siano et al. enriched durum wheat pasta with germ flour and examined the inhibitory effect of this pasta on carbohydrate-digesting enzymes in a laboratory environment.
Things to Consider for Celiac Patients
The reference to germ flour as "gluten-like" may lead to confusion among some consumers. Scientific findings suggest that caroubin has a different protein system than wheat gluten; however, the suitability of a product for celiacs and gluten-sensitive individuals depends not only on the nature of the raw material but also on the risk of cross-contamination on the production line and whether the product is labeled gluten-free.
- People on a gluten-free diet should look for the phrase "gluten-free" and the corresponding certification on products containing germ meal.
- If wheat products are processed in the same facility in germ meal production, the risk of cross-contamination should be evaluated separately.
- It is recommended that celiac patients consult their physician or dietitian before adding a new product to their diet.
This content is for informational purposes only; it is not a substitute for medical advice.
Outside Food: Feed and Other Evaluation Areas
Since germ meal is rich in protein, it is also used in animal nutrition. In studies conducted in aquaculture, carob seed germ meal was partially used instead of fish meal; for example, Couto et al. examined the effects of germ meal on growth, digestive enzymes and liver-intestinal histology in increasing proportions in the offspring of Yellowmouth (Argyrosomus regius). Such studies show that germ is seen as an alternative source of vegetable protein not only in food but also in the feed industry.
Laaraj et al.'s comprehensive review dated 2023 also states that carob seed components; It summarizes that it can be evaluated in different sectors through gum, protein, fat and phenolic compounds. Germ flour's place in this spectrum is that it converts a by-product of gum production into a high-protein raw material.
Frequently Asked Questions
Is carob germ meal the same as carob flour? Carob flour (powder) is obtained from the fleshy part of the fruit and is rich in sugar and fiber. Germ flour, on the other hand, is obtained from the embryo inside the kernel and is rich in protein.
Is Caroubin gluten? Caroubin is a carob germ protein that shows viscoelastic properties similar to gluten; however, research shows that its chemical composition is markedly different from wheat gluten and no prolamins are detected in germ proteins.
Can germ flour be used alone in bread making? In studies, germ flour has generally been used in low proportions with starch and hydrocolloids. Its use as bread flour alone is not the typical approach in research.
Where does germ flour come from? In the production of carob gum, the endosperm of the nucleus is separated, while the rest comes from the embryo part; therefore, it is a by-product of gum production.
The Value of Carob Seeds with Carob Türkiye
Carob kernel; When evaluated together with the shell, endosperm and germ sections, it presents a raw material chain extending from gum to protein. The starting point of this chain is the clean, classified and regularly supplied nucleus.
At Carob Türkiye, we supply carob fruit, crumb, flour/powder, kernel and extract. For the structure of the kernel What is Carob Seed? For product information, Carob Seed You can review our page. For your wholesale and export requests Contact Now You can contact us on our page.
Foreign sources
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org/ 10. 1094/ CCHEM. 1998. 75. 4. 488 Smith, B. M., Bean, S. R., Schober, T. J., Tilley, M., Herald, T. J., Aramouni, F., "Composition and molecular weight distribution of carob germ protein fractions", Journal of Agricultural and Food Chemistry, 2010, 58(13), 7794–7800. doi.
org/ 10. 1021/ jf101523p Smith, B. M., Bean, S. R., Herald, T. J., Aramouni, F. M., "Effect of HPMC on the quality of wheat-free bread made from carob germ flour-starch mixtures", Journal of Food Science, 2012, 77(6), C684–C689. doi.
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org/ 10. 1016/ j. foodchem. 2007. 08. 069 Custódio, L., Escapa, A. L., Fernandes, E. et al., "Phytochemical profile, antioxidant and cytotoxic activities of the carob tree (Ceratonia siliqua L.) germ flour extracts", Plant Foods for Human Nutrition, 2011, 66(1), 78–84. doi.
org/ 10. 1007/ S11130- 011- 0214- 8 Siano, F., Mamone, G., Vasca, E., Puppo, M. C., Picariello, G., "Pasta fortified with C-glycosides-rich carob (Ceratonia siliqua L.) seed germ flour: Inhibitory activity against carbohydrate digesting enzymes", Food Research International, 2023, 170, 112962. doi.
org/ 10. 1016/ j. foodres. 2023. 112962 Jang, Y. J., Said, N. S., Na, Y. J., Lee, W. Y., "Comparative Effects of Inulin, Psyllium Husk, and Carob Seed Germ Flour as Fiber-Enriching Ingredients on the Quality of Baromi-2 Rice Flour-Based Gluten-Free Bread", Journal of Texture Studies, 2026, 57(4), e70099. doi.
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