Utilization of Carob Waste and Circular Economy
When carob is processed, gum is obtained from the kernel, flour, molasses or sugar syrup is obtained from the fruit flesh; each of these processes leaves behind by-products such as pulp, seed shell and germ. The circular economy approach aims to evaluate these streams as raw materials for new products instead of being seen as waste.
In this article, we discuss which by-products emerge in carob processing, how they are investigated in the fields of food, feed, fermentation and materials, and the practical challenges encountered in application in the light of scientific studies.
Where Do By-Products Come From in Carob Processing?
Carob pods are economically divided into two main parts: the kernel and the pulp. The compilation by Rodríguez-Solana et al. (2021) states that the kernel is the valuable part from which the carob gamut is obtained, while the fruit flesh is seen as a by-product of the fruit processing industry. The same review emphasizes that the fruit flesh is a valuable mixture containing carbohydrates, vitamins, minerals and functional secondary metabolites, and in recent years, many studies have been carried out to increase its commercial use.
The main by-products that occur at different points in the processing chain are:
| By-product | The process by which it emerged | Explored evaluation pathways |
|---|---|---|
| Core shell | Debarking before gum production | Source of antioxidant components, food additive |
| Germ (nucleus embryo) | Separation of endosperm | Protein-rich flour, feed raw material |
| Molasses and syrup pulp | Extracting sugars from fruit pulp with water | Fibrous food ingredient, fermentation substrate |
| Desugared fruit flesh | Industrial sugar extraction | Biofuel, biochar, feed |
| Under-sieve and non-quality parts | Crushing, screening and classification | Feed, fermentation |
The composition of each of these by-products is different. For example, the kernel shell is of interest in terms of polyphenols, while molasses pulp is a material that has removed most of its sugars, but retains its fiber and phenolic components. Therefore, "carob waste" is not a single material, but a group of streams that require different ways of evaluation.
By-Products of Core Processing: Shell and Germ
The locust bean range is derived from the endosperm in the middle of the nucleus. For this, the nucleus must first be freed from its hard shell, and then the endosperm must be separated from the germ. This process leaves two important by-products, the shell and the germ.
Core shell: Medronho et al. (2025) sought to develop a more moderate and sustainable method, stating that the dehulling process required for gum extraction was traditionally done under harsh conditions. In the study, it was reported that the kernels processed with the optimized acidic water-based system remained morphologically whole and their color characteristics were comparable to commercial samples. The change in the hulling method also directly affects how the resulting bark flow can be evaluated. Martin-Diana et al. (2017) examined the utilization of carob germin and kernel bark as natural antioxidant components in gluten-free crackers.
Germ: The Feedipedia database, which compiles animal feed sources, defines carob germ meal as a by-product of gum extraction and shows it as a protein-rich feed ingredient with about 50 percent crude protein in dry matter (Feedipedia). The use of germ meal in food is a separate issue and is being investigated in gluten-free products due to the gluten-like properties of germ proteins.
There is a similar approach at the whole seed level. Santonocito et al. (2020) examined extracts of carob seeds, which have been largely seen as waste for centuries; they reported that especially mature seed extracts show interesting antioxidant activity thanks to their procyanidin content and that these extracts can be evaluated in the field of nutritional supplements and nutraceuticals.
Molasses and Syrup Pulp: Back to Food
In the production of carob molasses, fruit pieces are processed with water and sugars are taken into the liquid phase. The remaining solid part, namely molasses pulp, is one of the most studied flows among carob by-products in Turkey. Stages of molasses production What is Carob Molasses and How is it Made? We explained it in our article.
Two recent studies conducted in Turkey provide concrete examples of how this fiber can be recycled into food:
Spreadable cheese study: Özbek and Özdemir (2024) added 5, 10, and 15 percent carob molasses pulp to the formula while transforming Tort cheese, the traditional cheese of the Mediterranean Region, into a spreadable product. The addition of pulp increased the dry matter, ash, carbohydrate, antioxidant activity, and total phenolic substance content of the cheeses, while reducing the fat and protein content. The most appreciated example in sensory evaluation was cheese containing 5 percent pulp. This study is also a good example of the circular economy in terms of evaluating two different by-products (whey and molasses pulp) in the same product.
Functional bread operation: Tusat et al. (2025) developed white bread enriched with carob molasses pulp flour and wheat germ. The test bread, which contained 20 percent pulp flour and 20 percent wheat germ, contained significantly higher fiber, polyphenols, antioxidants, and resistant starch than the control bread. In the short-term intervention with healthy volunteers, no significant difference was observed in blood glucose and oxidative status indicators; however, the test bread increased the feeling of satiety.
These two studies show that pulp may not only be a "filling material", but also a component that contributes to the nutritional profile of the product. However, the results should be interpreted in moderation: as in the bread study, the improvement in composition may not always translate into a measurable health effect.
Fermentation Evaluation: Bioethanol and Biopolymer
The high sugar content of carob makes it a suitable food source for microorganisms. For this reason, both the fruit itself and the solid waste left over from syrup production are frequently used in fermentation research.
In a study involving Turkish researchers, Turhan et al. (2010) examined the conversion of extract obtained from carob fruit into ethanol with the yeast Saccharomyces cerevisiae; the study was discussed in the context of the use of agricultural products that are not used in renewable energy production. In a study conducted in Lebanon, Bahry et al. (2017) described a process for the production of second-generation bioethanol from solid waste left over from carob syrup preparation. It has been reported that solid-state fermentation is simpler to operate, requires less water, and can reach ethanol production of up to 155 grams per kilogram of waste.
Fermentation is not limited to fuel production alone. Djerrab et al. (2022) demonstrated the production of polyhydroxybutyrate (PHB), a biodegradable biopolymer, with a strain of Bacillus at laboratory scale, using molasses from leftover carob fruits as a carbon source. Such studies indicate that carob by-products can also be a source of high value-added products, such as plastic alternatives.
Materials and Energy: The Case of Biochar
Another option for carob residues that have been desugared and cannot be used for food or fermentation is the production of energy and materials by heat treatment. Infurna et al. (2022) pyrolysis the carob waste left after glucose extraction in a local factory producing carob confectionery. In the process, biofuel was first obtained, and then the remaining solid fraction (biochar) was added to a biodegradable plastic (PBAT) as a filler material. It has been reported that biochar particles can have a retarding effect on the oxidation of the plastic matrix by light in accelerated aging tests.
This example is in line with the principles of the circular economy in that it illustrates a "gradual" use of which energy is obtained first and then materials from the same waste stream.
Evaluation in Animal Feed
One of the oldest and most common ways of evaluating carob and its by-products is animal feed. According to Feedipedia, whole ground pods can be used in both ruminant and non-ruminant animals; pitted, sugar-rich dried fruit flesh (kibble) and germ meal, which is a by-product of gum production, are also among the feed raw materials. The same source emphasizes that carob pods and by-products contain significant amounts of tannins and that the tannin content may limit the rate of use in animal rations (Feedipedia).
The use of feed offers a practical outlet for streams that cannot be converted into food but have nutritional value. However, moisture, mold and mycotoxin control are important here as well; especially wet pulp should be dried without waiting or used in a short time.
Gradual Evaluation in Terms of Circular Economy
The basic idea in the circular economy is to preserve the value of a resource for the longest possible time and at the highest level. For carob by-products, this approach can generally be considered in the following order of priority:
| Food component | Fiber and polyphenol preserved pulp and shell extracts |
| Nutraceutical and cosmetic raw materials | Antioxidant extracts from seeds and shells |
| Animal feed | Germ flour, kibble and sieve parts |
| Fermentation products | Bioethanol, organic acids, biopolymers |
| Materials and energy | Pyrolysis, biochar and biofuel |
This order is not a strict rule; which route is chosen depends on the composition and quantity of the by-product, the markets close to the plant, and economic conditions. However, the general principle is to examine whether a stream can be considered human food or a high value-added product first, and if this is not possible, the feed, fermentation, and energy options, respectively.
Challenges Faced in Implementation
Most laboratory studies show that carob by-products can be evaluated technically. Moving them to a commercial scale requires solving some practical problems:
| Seasonality | The flow of by-products is not regular throughout the year, as harvesting and processing are concentrated during certain periods. |
| Moisture and degradation | Wet pulp is susceptible to microbial spoilage in a short time; drying requires additional energy and cost. |
| Composition variability | The variety, the year of harvest and the conditions of processing change the characteristics of the by-product. |
| Food safety and legislation | By-products that will return to food must be collected in accordance with food hygiene rules and must be traceable. |
| Economies of Scale | Applications such as bioethanol and biopolymer can only become economical with an adequate and continuous flow of raw materials. |
These challenges demonstrate that the evaluation of carob by-products is not just a matter of technology; it requires logistics, quality management, and cross-industry collaboration.
Frequently Asked Questions
What does carob molasses pulp do? Studies conducted in Turkey have shown that molasses pulp can be used as a source of fiber and phenolic substances in products such as bread and spreadable cheese. Pulp can also be used as feed and fermentation raw material.
Is the shell of carob seed waste? Although traditionally seen as a by-product, research shows that bark and kernel extracts can be a source of antioxidant components.
Can fuel be produced from carob? In laboratory and pilot-scale studies, it has been shown that bioethanol can be produced from carob extract and syrup waste. Commercial viability depends on raw material continuity and costs.
Can by-products be used safely in animal feed? Carob and its by-products are used in feed; however, tannin content may limit the rate of use and moisture and mold control is important. An animal nutritionist should be consulted for ration planning.
Sustainable Carob Sourcing with Carob Türkiye
Carob is a product that can be evaluated in almost every part when planned correctly. The seed can be turned into gum and stretching, the fruit flesh into flour, molasses and kibble, and the processing residues into feed, fermentation and material applications. This holistic view both increases economic value and reduces the environmental burden of production.
At Carob Türkiye, we supply carob fruit, crumbs, flour/powder, seeds, and extracts. For information about our products Carob Kibble (Granular), Carob Seed and Our Products You can review the pages, for your wholesale and export requests. You can contact us.
Domestic resources
Özbek, Ç., Özdemir, Y., "Revitalizing traditional Turkish tort cheese into spreadable form: Enhancing bioactive and sensory attributes with utilization of carob molasses pulp that is a food waste", Food Science & Nutrition, 12(8), 6034–6044, 2024 (study conducted in Turkey). doi.
org/ 10. 1002/ FSN3. 4239 Tuşat, E., Parlak, E., Yıldırım, G., Öztop, K., Gülşen, B., Özdemir, Y., Uysal, Y., "Impact of White Bread Fortified With Carob Molasses Pulp Flour and Wheat Germ on Glycemic Response and Antioxidant Capacity in Healthy Subjects", Food Science & Nutrition, 13(12), e71046, 2025 (study conducted in Turkey). doi.
org/ 10. 1002/ FSN3. 71046 Turhan, I., Bialka, K. L., Demirci, A., Karhan, M., "Ethanol production from carob extract by using Saccharomyces cerevisiae", Bioresource Technology, 101(14), 5290–5296, 2010 (study involving Turkish researchers). doi.
org/ 10. 1016/ j. Biortech. 2010. 01. 146 Foreign sources
Rodríguez-Solana, R., Romano, A., Moreno-Rojas, J. M., "Carob Pulp: A Nutritional and Functional By-Product Worldwide Spread in the Formulation of Different Food Products and Beverages. A Review", Processes, 9(7), 1146, 2021. doi.
org/ 10. 3390/ pr9071146 Medronho, B., Boutoub, O., Duarte, H., Aliaño-González, M. J., Guerra, R., Brázio, A., Gonçalves, S., Romano, A., "On the Optimization of Carob Seed Peel Extraction Using Aqueous-Based Acidic Systems", Molecules, 30(7), 1397, 2025. doi.
org/ 10. 3390/ molecules30071397 Martin-Diana, A. B., Izquierdo, N., Albertos, I., Sanchez, M. S., Herrero, A., Sanz, M. A., Rico, D., "Valorization of Carob's Germ and Seed Peel as Natural Antioxidant Ingredients in Gluten-Free Crackers", Journal of Food Processing and Preservation, 41(2), e12770, 2017. doi.
org/ 10. 1111/ jfpp. 12770 Santonocito, D., Granata, G., Geraci, C., Panico, A., Siciliano, E. A., Raciti, G., Puglia, C., "Carob Seeds: Food Waste or Source of Bioactive Compounds?", Pharmaceutics, 12(11), 1090, 2020. doi.
org/ 10. 3390/ pharmaceutics12111090 Bahry, H., Pons, A., Abdallah, R., Pierre, G., Delattre, C., Fayad, N., Taha, S., Vial, C., "Valorization of carob waste: Definition of a second-generation bioethanol production process", Bioresource Technology, 235, 25–34, 2017. doi.
org/ 10. 1016/ j. Biortech. 2017. 03. 056 Djerrab, L., Chekroud, Z., Rouabhia, A., Dems, M. A., Attailia, I., Garcia, L. I. R., Smadi, M. A., "Potential use of Bacillus paramycoides for the production of the biopolymer polyhydroxybutyrate from leftover carob fruit agro-waste", AIMS Microbiology, 8(3), 318–337, 2022. doi.
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