TECHNICAL FIELD

The invention relates to different emulsifiers with various properties that are suitable for emulsion systems with different oil-in-water ratios, consisting of products with high cellulose content obtained from plant residues containing relatively short fibers, and fatty acid esters. It also relates to the production method of these emulsifiers.

BACKGROUND OF THE INVENTION

Cellulose, one of the most abundant polymers in nature, can be used directly in the paper industry or can be esterified with fatty acids to produce biodegradable packaging with different properties. Thus, cellulose sources can be transformed into high value- added products. However, food industry residues containing relatively short cellulose fibers are not suitable for use in either the paper industry or the production of biodegradable packaging. Consequently, they cannot be converted into high value-added products. On the other hand, many products in the food industry are produced using emulsifiers, and the use of natural emulsifiers in the production of some emulsion products is not possible. As a result, more additives and artificial emulsifiers are used. Furthermore, in some oil-in-water emulsion systems, more additives and/or synthetic emulsifiers are used to ensure appropriate physical properties in the final product.

Food industry by products, which contain relatively short fibers with a high cellulose content, are used in animal feeding or as fuel. Therefore, these products with a high cellulose content are considered as low-value by-products.

BRIEF DESCRIPTION OF THE INVENTION

Emulsifiers are substances found as food components in the production of certain foods, necessary for mixing two or more liquids, such as water and oil, which don't mix with each other. They also positively influence the viscosity, texture, and sensory properties of foods by preventing physical defects that may occur depending on the shelf life of foods. This function of emulsifiers originates from one end of the molecule being attracted to water (hydrophilic) and the other end having a higher affinity for oil (lipophilic). Emulsifiers ensuring emulsion stability are called surfactants or emulsion agents.

Emulsifiers are categorized into natural (proteins, phospholipids, bile acids, glycolipids, saponins, etc.) and artificial (Stearyl-2-lactylate, Datem, Citrem, monoglycerides and diglycerides and their acetic and lactic acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, etc.) emulsifiers. The most well-known and used emulsifiers in the food industry are monoglycerides and/or diglycerides and lecithin. As illustrated by the given examples, emulsifiers are generally artificial or natural products obtained by esterifying a hydrophilic component with a lipophilic component.

The most commonly used emulsifiers in the food industry, mono and diglycerides, are produced by methods such as hydrolysis of triglycerides, glycerolysis of triglycerides, direct esterification of glycerol and fatty acids, and transesterification of glycerol and methyl esters of fatty acids. Another significant emulsifier, lecithin, is primarily obtained from sunflower and soybean using acetone application or low-temperature ultrafiltration. If organic solvents are used in the production process, lecithin contains a residue of acetone, which is a chemical solvent.

The ratios of lipophilic and hydrophilic groups in emulsifiers influence their areas of use. For emulsifiers suitable for oil-in-water emulsion types, it's necessary to have a larger hydrophilic portion, while for those suitable for water-in-oil emulsion types, the lipophilic portion needs to be more dominant.

Within the scope of our invention, emulsifiers suitable for oil-in-water (O/W) emulsion systems have been produced using residues of corn cob, wheat bran, and sunflower receptacle, all containing relatively short fibers. Consequently, high-value endproducts have been obtained from these high cellulose content residues. Raw materials with a high cellulose content are typically used in the paper or packaging industries. However, for them to be used in these fields, the cellulose fibers they contain need to have long chains. Indeed, because wheat bran, corn cob, and sunflower receptacle contain short cellulose fibers, they are not used in the paper and packaging industries. Therefore, the evaluation of these residues has been carried out within the scope of our invention.

With the method subject to the invention, it's possible to produce different emulsifiers for emulsion systems with varying oil-in-water ratios, using different raw materials and production conditions. Additionally, depending on the raw materials and method conditions used in production, the obtained emulsifiers have different rheological and physical effects in oil-in-water (O/W) emulsion systems. Therefore, there's an advantage of ensuring diverse rheological and physical properties for the emulsion system. On the other hand, it is also suitable for use with a wide range of raw materials.

LIST OF FIGURES

Figure 1a. Effect of fatty acid chlorite salt quantity on the degree of esterification. Figure 1 b. Effect of type of fatty acid chlorite salts on the degree of esterification.

Figure 2. Effect of the degree of esterification on emulsion formation in water-in-oil emulsion systems formed with caproic acid-cellulose high-content nanofiber esters.

Figure 3. Effect of the degree of esterification on emulsion formation in water-in-oil emulsion systems formed with lauric acid-cellulose high-content nanofiber esters.

Figure 4. Effect of the degree of esterification on emulsion formation in water-in-oil emulsion systems formed with oleic acid-cellulose high-content nanofiber esters.

Figure 5. Effect of the degree of esterification on emulsion formation in water-in-oil emulsion systems formed with stearic acid-cellulose high-content nanofiber esters.

DETAILED DESCRIPTION OF THE INVENTION

Within the scope of the invention, firstly, nanofibers with high cellulose content were obtained using at least one of wheat bran, corn cob, and sunflower receptacle. The aim of this is because fibers found in plant sources exist in clusters, leading to a significant portion of hydrophilic (-OH) groups being enclosed. With the separation of these fiber clusters, the exposure of hydrophilic groups (-OH) in the high-content cellulose nanofibers has been achieved. Later, some of these -OH groups have been esterified with lipophilic components (fatty acids with different chain lengths) to produce products that have both lipophilic and hydrophilic groups. To obtain high cellulose content nanofibers, a colloid mill and microfluidizer device were used after the delignification process. For this purpose, plant sources (wheat bran, corn cob, and sunflower receptacle) were placed in alkaline water (pH value 10-14) containing NaOH at 80°C after necessary fragmentation processes. After being left for 48 hours to allow the lignin in the structure to separate, they were rinsed with pure water until its dark color disappeared (until pH value reached 7). The obtained fibers were subjected to size reduction in a colloid mill. For this, the fibers were passed three times through a colloid mill at a rotation speed of 10000-12000 rpm, reducing their size to levels that would form a colloidal solution. In the final step, fibers, whose size was reduced with the colloid mill, were passed through microchannels in a high-pressure microfluidic device at a pressure of 12000-15000 psi to obtain high cellulose content nanofibers. These fibers were then frozen at (-)70°C, dried under vacuum at (-)90°C using a freeze-drying device, and stored at (-)70°C.

Within the scope of the invention, after mixing the high-cellulose-content nanofibers produced with the chlorite salts of caproic acid, lauric acid, stearic acid, and oleic acid, optimization studies for the esterification process have been conducted. The purpose of using these fatty acids is that cellulose fibers have only hydrophilic groups (-OH), do not function as emulsifiers. However, they can be used in emulsion systems for the function of thickening in addition to emulsifiers. By esterifying some of the -OH groups that cellulose fibers possess with fatty acids, the addition of lipophilic groups to the structure is ensured. Thus, final products possessing both hydrophilic and lipophilic groups, meaning groups that attracts both water and oil, can be used for emulsion systems. However, as previously mentioned, for the emulsion to form, not only the size of the cellulose fibers but also the chain length of the fatty acids added to the structure is important. Indeed, as the chain length of the fatty acids increases, their lipophilic property increases. On the other hand, due to cellulose monomers containing three -OH groups, the degree of esterification, meaning the level of binding of the fatty acid to cellulose, can be at most three. If the degree of esterification is three, since the hydrophilic groups of cellulose are completely bound with fatty acids, there won't be any hydrophilic groups left. Therefore, it will not be able to act as an emulsifier. For this reason, if fatty acids suitable for the emulsion type are bound to cellulose at levels suitable for the emulsion type, they will have both hydrophilic and lipophilic groups.

In optimization studies, for every 1 mol of cellulose, 3 mols of Dimethylaminopyridine (DMAP) and the previously mentioned fatty acid chlorite salts (caproyl chlorite, lauryl chlorite, stearoyl chlorite, and oleoyl chlorite) were used in varying molar ratios (3-15 mol). Within the scope of the method, cellulose samples obtained from wheat bran, corn cob, and sunflower receptacle (0.5 g) were first dissolved in 20 mL DMAc (Dimethylacetamide) containing 6.7% LiCI at 50°C for one day. Subsequently, due to the cellulose monomers containing 3 -OH groups, 3 mols of Dimethylaminopyridine (DMAP) (in a 1 :3 ratio) were added as a catalyst to the samples, along with the aforementioned fatty acid chlorite salts in different molar ratios (3-15 mol). The reaction was facilitated at an adjusted temperature of 80°C in a water bath with a stirring speed of 75 rpm for a specific duration. At the end of the reaction, to halt the reaction and remove residues, 15 mL of methanol was added to the medium, which, after coarse filtration, was washed with 15 mL of 70% ethanol. To ensure no fatty acid residues remained in the washed samples, they underwent solvent extraction using hexane or a similar fat solvent with the Behr E6 device operating with the Randall method. Subsequently, a vacuum oven was used to evaporate the residual hexane (at 70° for 24 hours).

The degree of esterification of each produced sample was determined using the volumetric method. For this purpose, the produced esters were saponified with a 0.25M NaOH alcoholic solution at 70°C for 16 hours, and then titrated with 0.01 N hydrochloric acid, and the degree of esterification was determined.

To bind fatty acids to cellulose nanofibers, a specific amount of fatty acid is needed for a certain duration, depending on the amount of fatty acid. As a result of the study, as seen in Figure 1 a and Figure 1 b, it was determined that as the quantity of fatty acid chlorite salts increased, more fatty acids were attached; on the other hand, as the chain length of the fatty acid chlorite salts increased, fewer fatty acids were attached.

Considering that the glucose units forming cellulose have three reactive hydroxyl (OH) groups, the maximum degree of esterification can be three. Hence, based on the optimization results, 48 products (3x4x4) with four different degrees of esterification (approximately 0.5, 1 .25, 2, and 2.75±0.05) were reproduced using three different sources and four different fatty acids (Table 1 ).

Table 1. Actual and predicted esterification degrees of products produced according to parameters obtained from optimization results

No Time Fiber Source Fatty acids Mol of Predicted Actual

(min) fatty esterification esterification acids degrees degrees

1 60 Sunflower Caproic acid 3.0 0.49 0.51 ±0.01 receptacle

2 240 Sunflower Caproic acid 4.0 1.25 1.25±0.01 receptacle

3 250 Sunflower Caproic acid 7.0 1.99 2.04±0.02 receptacle

4 275 Sunflower Caproic acid 11.0 2.76 2.74±0.02 receptacle

5 60 Wheat bran Caproic acid 3.0 0.50 0.52±0.01

6 240 Wheat bran Caproic acid 4.0 1.26 1.24±0.01

7 250 Wheat bran Caproic acid 7.0 2.00 1.98±0.02

8 275 Wheat bran Caproic acid 11.0 2.77 2.74±0.02

9 60 Corn cob Caproic acid 3.0 0.51 0.53±0.01

10 240 Corn cob Caproic acid 4.0 1.24 1.27±0.01

11 250 Corn cob Caproic acid 7.0 1 .98 2.02±0.02

12 275 Corn cob Caproic acid 11.0 2.75 2.77±0.03

13 60 Sunflower Lauric acid 3.1 0.50 0.47±0.01 receptacle

14 240 Sunflower Lauric acid 4.2 1.25 1.27±0.01 receptacle

15 250 Sunflower Lauric acid 7.3 2.00 2.03±0.02 receptacle 275 Sunflower Lauric acid 11.4 2.75 2.76±0.02 receptacle

60 Wheat bran Lauric acid 3.1 0.51 0.49±0.01

240 Wheat bran Lauric acid 4.2 1 .25 1.27±0.01

250 Wheat bran Lauric acid 7.3 2.01 2.02±0.02

275 Wheat bran Lauric acid 11.4 2.75 2.73±0.02

60 Corn cob Lauric acid 3.1 0.52 0.48±0.01

240 Corn cob Lauric acid 4.2 1 .25 1.23±0.02

250 Corn cob Lauric acid 7.3 1 .99 2.02±0.02

275 Corn cob Lauric acid 11.4 2.76 2.74±0.03

60 Sunflower Oleic acid 3.2 0.50 0.51±0.01 receptacle

240 Sunflower Oleic acid 4.3 1.24 1.28±0.01 receptacle

250 Sunflower Oleic acid 7.5 1.98 1.99±0.02 receptacle

275 Sunflower Oleic acid 11.8 2.75 2.78±0.02 receptacle

60 Wheat bran Oleic acid 3.2 0.50 0.51±0.01

240 Wheat bran Oleic acid 4.3 1.24 1.22±0.01

250 Wheat bran Oleic acid 7.5 1.99 2.00±0.02

275 Wheat bran Oleic acid 11.8 2.75 2.78±0.03

60 Corn cob Oleic acid 3.2 0.51 0.49±0.01

240 Corn cob Oleic acid 4.3 1.24 1.22±0.01

250 Corn cob Oleic acid 7.5 2.00 2.03±0.02

275 Corn cob Oleic acid 11.8 2.76 2.74±0.02

60 Sunflower Stearic acid 3.4 0.52 0.48±0.01 receptacle

240 Sunflower Stearic acid 4.5 1 .26 1.24±0.02 receptacle 9 250 Sunflower Stearic acid 8.0 2.01 1.99±0.02 receptacle 0 275 Sunflower Stearic acid 12.0 2.77 2.73±0.02 receptacle 1 60 Wheat bran Stearic acid 3.4 0.50 0.53±0.012 240 Wheat bran Stearic acid 4.5 1.24 1.28±0.013 250 Wheat bran Stearic acid 8.0 1.98 2.01 ±0.024 275 Wheat bran Stearic acid 12.0 2.75 2.71 ±0.025 60 Corn cob Stearic acid 3.4 0.52 0.52±0.016 240 Corn cob Stearic acid 4.5 1.25 1.23±0.017 250 Corn cob Stearic acid 8.0 1 .99 2.03±0.028 275 Corn cob Stearic acid 12.0 2.76 2.73±0.02

In the scope of the invention, products were obtained using water-in-oil emulsions, which were produced by homogenizing sunflower oil and pure water in weight percentages of 15%, 25%, and 35%. Nanofiber-fatty acid esters, esterified at different ratios from different fatty acids, were first mixed with pure water in weight ratios of 0.5-1 % using an Ultra-Turrax device (at 5000 rpm). Later, while adding oil, the homogenization process continued with the Ultra-Turrax device (for 5 minutes).

At this stage, a total of 48 nanofiber-fatty acid esters, which have four different esterification degrees and are produced from three different raw materials and four different fatty acids, were tested in six different oil-water mixtures using four different ratios. At this phase, the surface scanning method was used, and the number of productions was reduced to 46, as shown in Table 2.

Table 2. Experimental design of oil-in-water emulsions

To determine which type of emulsion is suitable for the emulsifiers produced within the scope of the invention, emulsions that remained stable for a day under room conditions are considered to have formed. For the statistical analyses of the results obtained within the scope of the invention and for creating three-dimensional figures, a value of “1” was given for samples where emulsion formation took place and “0” for those where it did not. As seen from Figure 2 and Figure 3, cellulose-rich nanofiber caproic and lauric acid esters with an esterification degree of 0.50-1.25 are suitable for water (85-65%) in oil (15-35%) emulsions, while those with an esterification degree above 1 .25 are not suitable.

As seen from Figure 4 and Figure 5, cellulose-rich nanofiber oleic and stearic acid esters with an esterification degree of 0.50 are suitable for water-in-oil emulsions, while those with an esterification degree above 0.50 are found to be unsuitable.

From the results, it is understood that for water-in-oil (o/w) emulsions, short-chain fatty acid-cellulose-rich nanofiber esters (caproic acid and lauric acid) with an esterification degree of 1.25 and below should be used, while long-chain fatty acid- cellulose-rich nanofiber esters (oleic acid and stearic acid) should have an esterification degree of at most 0.5. After determining which product is suitable for which type of emulsion by looking at the emulsion formation status, emulsions were formed again, and the rheological and physical properties of the final products were determined depending on the emulsion type and the used emulsifier. As a result of the analyses, it was determined that the type of emulsifier used has significant effects on the physical and rheological properties of the emulsions. Thus, it was determined that emulsions with the same oil/water ratio but different rheological/physical properties could be obtained using different emulsifiers described within the scope of this invention.