Innovative Approach of Cheese Making from Camel Milk: A Review

Abstract

Camel milk contains all essential important components of human diet and generates cash, ensures food security, and provides health benefits. Compared to cow milk, camel milk has higher levels of whey protein, lower levels of αs1-casein, larger size of κ-casein, and a very low κ- to β-casein ratio. As a result, the technical characteristic of the acidic or enzymatic coagulation process of camel milk for cheese making is affected by all these factors. Camel milk cheese is a recent product that enters into both the domestic and global milk product markets. Cheese made from camel milk can have processing issues and be of lower quality if it is produced using the same technology as dairy products made from bovine milk. To maximize the possibility of manufacturing cheese from camel milk, various trials were conducted over time utilizing different methods. This chapter reviews the advancements in making cheeses from camel milk using starter cultures and coagulants. Furthermore, the relevant studies describing the fortification of camel milk with ingredients for cheese making are included.

1. Introduction

Milk is believed to be the most essential product obtained from dairy animals including camel (Dromedary), being a complete food, helps to provide a nutritious and balanced diet to nomadic desert people under harsh conditions [1, 2]. Many people give a great value to camel milk because it is essential to their nutrition in the Gulf Cooperation Council, Middle East, Middle Asian, and African nations [3]. Additionally, it has been claimed that camel milk helps households in pastoral areas to generate cash, ensure food security, and provide health benefits [4]. A significant source of protein, fat, lactose, vitamins, and minerals can be found in camel milk. All of the essential amino acids are also present in camel milk’s protein, while unsaturated aliphatic fatty acids are present in the fat. Furthermore, compared to cow milk, camel milk has higher levels of whey protein, lower levels of αs1-casein, and a very low kappa- to beta-casein ratio. The technological characteristics of the acidic or enzymatic coagulation process of milk are affected by all these factors, which cause the final curd to almost be weak and brittle, and have an open body and texture [5, 6, 7].

Even though the gross composition of camel milk is similar to bovine milk, the relative composition, distribution, and the molecular structure of the milk components are reported to be different. Consequently, manufacturing camel dairy products such as cheese, yogurt, or butter using the same technology as dairy products from bovine milk can result in processing difficulties and products of inferior quality [5]. As a result, camel milk is consumed, usually in a raw form by the people living in remote areas where camels are reared. On some occasions, to extend its shelf-life, this milk is consumed in a fermented form [4, 8]. However, scientific evidence points to the possibility of transforming camel milk into products by optimization of the processing parameters [5].

Camel milk is a newcomer to domestic markets and especially to the international milk market. This recent emergence has been accompanied by a diversification of processed products, based on the technologies developed for milk from other dairy species. However, technical innovations had to be adapted to a product with specific behavior and composition. The transformation of camel milk into dairy products such as fermented milk, cheese, powder, or other products was supported, under the pressure of commercial development, by technological innovations made possible by a basic and applied research position. Through time differences, trials were done using different methods or parameters, fortification with ingredients, starter cultures, and milk coagulants to optimize possibility of cheese making from camel milk [9, 10].

The coagulation of bovine milk is faster than camel milk since the casein micelles of the former milk are very smaller in size and coagulated within a short period of time. However, the processing of camel milk into cheese is technically more difficult than the milk of the other domestic dairy animals under the same conditions. This is mainly due to the lower contents of total solids content, αs1- casein, and κ-casein as well as the large casein micelles, which may relate to the poor rennet ability of camel milk [8, 9]. Trials on cheese prepared from camel milk by direct acidification adding starter culture of lactic acid bacteria [11], and soft white cheese from camel milk [12] were evaluated. Recently, researches have been done on fortification of camel milk to improve soft cheese using milky component and sweet potato powder [7]. Moreover, mixing of camel milk with other dairy animal milk have been researched for cheese making. Even the process of developing camel milk into cheese alone is a novel; additionally, scientific innovations have been made to enhance the production of cheese from camel milk, including the use of starter cultures, coagulants, and fortification of camel milk. Therefore, the aim of this chapter is to review technological advances for cheese making from camel milk.

2. Effect of starter cultures on camel milk cheese properties

The diversity of the camel milk microflora is vital for both the antibacterial activity and acidity of the milk, both of which are necessary for the fermentation of milk products and the making of cheese. However, because camel milk proteins have stronger antibacterial characteristics than those in cow milk and, in certain circumstances, because camel milk samples have poorer sanitary conditions, the acidification process appears to be slower for camel milk than for cow milk. In order to increase the shelf life of liquids that have been consumed since the dawn of time, technical advancements involving fermented camel milk have been made [9]. According to studies, in order to produce camel milk cheese, the pH must first be acidified in order to reduce it to about 6.4 before enzymes are added to shorten the clotting time. Some studies reported that reducing the pH of camel milk to 5.6 at temperatures up to 42⁰C further reduces the coagulation time. It is possible to directly acidify milk by adding acid or glucono-6-lactone, although it is more customary to do so indirectly by using cultures that may create lactic acid [13]. It is vital to highlight that starter cultures have a considerable impact on the yield, nutritional content, textures, and sensory quality of camel milk cheeses. Mesophilic, thermophilic, or a combination of these starters were employed to treat camel milk for cheese making or fermentation, and they resulted in an acidification rate that was between 33% and 79% lower at 37^°C than for cow milk [5, 9, 12]. Thus, starter cultures are added to cheese milk for acidification affecting several aspects of the cheese manufacturing process and finally cheese composition through the production of lactic acid with the resulting in pH reduction.

2.1 Acidification process of starter culture

The study conducted the effects of five different commercial starter cultures as shown in Table 1 [starter cultures; i.e., 1 thermophilic (STI-12), 2 blended (RST-743 and XPL- 2), and 2 mesophilic (R-707 and CHN-22) cultures; starter cultures STI-12 and RST-743 were inoculated at 37°C, whereas XPL-2, R-707, and CHN-22 were inoculated at 30°C] on physicochemical properties of soft white cheese (SWC) revealed that camel milk inoculated using STI-12 and RST-743 cultures resulted in faster acidification than XPL-2, R-707, and CHN-22 cultures [12].

Culture	Type	Composition
STI-12	Thermophilic	Streptococcus thermophilus
RST-743	Blended	Lactococcus lactis and Streptococcus thermophilus
R-707	Mesophilic	Lactococcus lactis without biovar diacetylactis
XPL-2	Blended	Lactococcus lactis ssp. cremoris, Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. lactis biovar diacetylactis, Leuconostoc species, and Streptococcus thermophilus
CHN-22	Mesophilic	Lactococcus lactis ssp. cremoris, Leuconostoc pseudomesenteroides, Lactococcus lactis ssp. lactis biovar diacetylactis, Lactococcus lactis ssp. lactis, and Leuconostoc mesenteroides

Table 1.

Composition of commercial starter cultures; Blended = mixture of mesophilic and thermophilic cultures.

It has been noted that starter cultures with slower rates of acidification (Table 2) produced cheese curds that were less vigorous. As a result, it was challenging to transfer camel milk curds inoculated with the XPL-2 and CHN-22 cultures from the cheese vat to the mold, and the majority of the fine grains were lost in the whey [12]. The variations in acidification time and pH values may be attributed to differences among starter cultures in rate and intensity of acidification.

			Starter culture
Time (min)	STI-12	RST-743	R-707	XPL-2	CHN-22	P-value
0	6.45 ± 0.01^b	6.47 ± 0.01^c	6.52 ± 0.00^a	6.51 ± 0.00^a	6.52 ± 0.01^a	*
10	6.41 ± 0.00^c	6.39 ± 0.00^c	6.47 ± 0.01^b	6.49 ± 0.01^ab	6.50 ±0.00^a	**
20	6.32 ± 0.01^d	6.34 ± 0.01^c	6.44 ± 0.01^b	6.47 ± 0.01^ab	6.49 ±0.00^a	**
30	6.24 ± 0.01^c	6.24 ± 0.02^c	6.40 ± 0.01^b	6.43 ± 0.01^ab	6.45 ±0.00^a	**
40	6.24 ± 0.01^c	6.24 ± 0.02^c	6.35 ± 0.01^b	6.38 ± 0.01^b	6.42 ±0.00^a	**
50	6.24 ± 0.01^c	6.24 ± 0.02^c	6.25 ± 0.02^b	6.32 ± 0.01^ab	6.36 ± 0.01^a	**
60	6.24 ± 0.01^b	6.24 ± 0.02^b	6.24 ± 0.01^b	6.27 ± 0.01^a	6.27 ± 0.00^a	***
70	6.24 ± 0.01	6.24 ± 0.02	6.24 ± 0.01	6.24 ± 0.00	6.24 ± 0.00	NS

Table 2.

Acidification rate of camel milk using different commercial starter cultures.

¹

pH values in the table are mean ± SD of n = 2. STI-12 and RST-743 were inoculated at 37°C, whereas R-707, XPL-2, and CHN-22 cultures were inoculated at 30°C for manufacturing of soft white cheese from camel milk.

^*

P < 0.05.

^**

P < 0.01.

^***

P < 0.001 [12].

^a–dMeans with different superscripts within the same row are significantly (P < 0.05) different.

2.2 Effect of starter cultures on camel milk cheese composition

It has been stated that a higher cheese yield (13.44 %) was obtained for cheese made using R-707 culture [12]. Khan et al. [11], who reported a 13.2% yield from fresh SWC made from camel milk using a starter culture, discovered the same outcome. SWC manufactured using the CHN-22 culture, on the other hand, was noted to have poor cheese production and greater moisture content. It is possible that this is a result of the extremely fragile cheese curd produced by this slowly acidifying culture, which causes a larger loss of tiny curd particles through the pores of the cheesecloth during whey drainage. The study found that by employing starter cultures, fresh soft white cheese could be produced. The most palatable cheese was discovered to be fresh, soft, and white, made from camel milk and starter culture. Without starting cultures, camel milk cheese had a very high pH and high moisture content, which could encourage the growth of harmful bacteria and result in major health issues [11].

When compared to other cultures, cheese prepared with RST-743 was shown to contain more fat. The strength of gels’ rheological and microstructural features, as well as the increased curd loss from the cheese vat, may all be contributing factors to these variances in cheese fat [13]. Additionally, it was discovered that the starter culture employed to make the cheese had a substantial impact on the protein, ash, and total solids contents of SWC [12]. The original milk composition and cheese-making processing conditions may be to blame for the fluctuation of TS seen in the cheese. Depending on how the cheese is processed and how the whey is drained, the majority of the TS constituents, such as protein and fat, are gradually concentrated into the cheese curd. Additionally, throughout the cheese-making process, the type, ash level, and salt addition can all have an impact on the minerals present in the cheese. The acidification process is crucial for the elimination of colloidal minerals from casein micelles, coagulant retention in the curd, syneresis of the gel, coagulum strength, and cheese yield, in addition to its effect on milk clotting.

2.3 Effect of starter culture on cheese texture

It was reported that compared to cheese made with the STI-12, R-707, XPL-2, or CHN-22 cultures, camel milk SWC made with the RST-743 culture had a stronger resistance to deformation. However, compared to SWC prepared from camel milk using the STI-12, RST-743, and R-707 cultures, camel milk SWC made using the XPL-2 and CHN-22 cultures showed lower deformation values. The enhanced resistance to deformation compared to camel milk soft cheese made with cultures R-707, XPL-2, and CHN-22 may be due to the lower moisture and higher TS levels of camel milk SWC manufactured with cultures STI-12 and RST-743 [12].

This study has notified that the moisture content and protein content of camel milk SWC produced with the XPL-2 culture were comparable to those of cheese produced with the RST-743 and STI-12 cultures. The SWC produced with XPL-2 suffered considerable syneresis during storage, in contrast to other cheeses, which may account for its low resistance to deformation [12]. The features of a cheese’s texture have been demonstrated to be influenced by its moisture content in the past [14, 15]. Cheese samples with lower moisture concentrations exhibit resistance to deformation. Acidification, which affects the cheese’s pH, and casein matrix hydration, which results in an increase in the curd’s stiffness with a pH decrease, both have an impact on the cheese-making process’s curd formation (Figure 1).

Figure 1.

Compression curves of soft white cheese (SWC), made from camel milk, using different starter cultures: Compression values from a single replication are shown from the texture analyzer software. The STI-12 and RST-743 cultures were inoculated at 37°C, whereas R-707, XPL-2, and CHN-22 cultures were inoculated at 30°C.

The study on SWC prepared from camel milk using several cultures found that the cheese’s textural attributes varied, see Ref. [12]. The report showed that compared to camel milk SWC prepared using other cultures, RST-743 SWC had significantly higher firmness and brittleness characteristics. A decrease in pH caused by the acidification of cheese milk during cheese production has an impact on the moisture content and, as a result, the mineral content of the cheese curd [16]. This has been explained by the degree of casein sub-micelle swelling brought on by the rise in the casein-to-moisture ratio. As a result, even minor changes in moisture content can have a big impact on how fresh cheese feels [17]. In addition to these, Ref. [18] examined how cheese’s microstructure and texture are affected by its fat level. They explained that increase in fat content result in smoother and softer cheese, and increase in casein content result in firmer cheese. It was also revealed that higher fat and water contents tend to weaken the protein structure of the cheese, as well as its texture [19].

2.4 Effect of starter cultures on sensory characteristics of camel milk cheese

Cheese’s sensory qualities are regarded as one of the key factors influencing consumer preference. The customer can detect a variety of cheese sensory qualities, which are commonly categorized under look, flavor, and texture. All of these characteristics influence cheeses’ acceptability and eating quality. There are many different kinds of cheese around the globe, each having a different sensory character. It reflects the properties of the milk used to make the cheese, the cheese-making environment, and the physical and chemical alterations that take place during ripening [20]. Since cheese can come in a wide variety, numerous trials are required in order to offer consumers a wide range of products. Different cheeses based on the techniques for producing feta and halloumi [8], soft unripened [21], gruyere [22], and mozzarella [18, 23] were examined, but the finished product’s texture, flavor, and taste did not match those of the bovine equivalent. In fact, when making cheese, the “proteinic-lipidic matrix” of camels behaves differently from milk to cattle. To comprehend the changes that occur during the various steps of acidification, coagulation, draining, brining, and refining as well as the impact of different starters and thermal treatments, such discrepancies between milk from different dairy species require more fundamental investigations of rheological properties.

With the exception of color preferences, it was reported, using a different starter culture affects test results for consumer preferences. In comparison with camel milk SWC made using STI-12, RST-743, and R-707 cultures, camel milk soft cheese made using XPL-2 and CHN-22 cultures received higher scores for flavor (aroma and taste). The similar outcome was discovered, showing that starter culture-prepared cheese samples were preferred over cheeses made through direct acidification with citric acid in terms of look, flavor, and texture [24]. The starting cultures XPL-2 and CHN-22’s natural abilities to produce aroma molecules like diacetyl may be the cause of the flavor variances. When citrate is co-fermented with lactose to make various kinds of cheese, lactic acid bacteria, particularly Lactococcus lactis biovar diacetylactis, naturally generate diacetyl [25]. The characteristics of the various commercial starter cultures utilized may be to blame for the variances in consumer preference test ratings in this study, particularly in appearance, scent, taste, and overall acceptability of the cheese samples. Additionally, substances including CO₂, diacetyl, and acetaldehyde may have contributed to the cheese developing unique texture and flavor characteristics [25, 26].

3. Use of coagulant in camel milk cheese

The difficulties in clotting found in this method should be explained by the different casein proportions between cow and camel milk, particularly the lower concentration of κ-casein: 3−4% of casein, compared to 13−15% in cow milk. Furthermore, camel milk’s casein micelles cannot coagulate well with the bovine chymosin utilized in the dairy industry, resulting in a weak curd. Therefore, the first difficulty addressed by researchers studying camels and dairy plants processing camel milk was obtaining a hard coagulum [9]. Animal rennins, such as pepsin and chymosin, plant-based proteases, starter cultures, or organic acids, for acidification are all utilized as coagulants while making cheese. After neutralizing the negative charges of the κ-casein, hydrolysis by enzymes or precipitation by acids lead to the instability and precipitation of the casein micelles, which is how milk coagulation with proteolytic enzymes proceeds [27, 28].

3.1 Animal source rennet enzymes

The animal source rennet enzymes are aspartic peptidase, and the most used are the combinations of chymosin A, B, C, and pepsin extracted from the stomach of calves and other ruminants [29]. When utilizing bovine chymosin, numerous investigations have consistently indicated that the coagulation of camel milk proceeds at significantly lower rates and results in a more fragile coagulum than that of bovine milk [30]. It was discovered that camel chymosin, which does not effectively coagulate camel milk, had 70% greater clotting activity for bovine milk than bovine chymosin [31]. Due to a lack of coagulation enzymes for camel milk, different researches have been conducted for substitute proteolytic enzymes that worked similarly. This led to the development of many microbial recombinant chymosin products as an alternative to animal rennet in the cheese-making process. Camel chymosin is a desirable alternative for both small- and large-scale cheese productions due to its high clotting activity [32].

Comparatively to the Phe105-Met106 bond in bovine κ-casein, camel and bovine chymosins preferentially cleave the Phe97-Ile98 bond in camel κ-casein. This results in the hydrophilic C terminal of κ-casein dissociating from it, destabilizing the casein micelles, and causing the milk to aggregate and coagulate as a result. Better substrate binding, made possible by camel chymosin’s surface charge, is thought to be the cause of its increased milk-clotting activity. By expressing the camel chymosin gene in a strain of Aspergillus niger, recombinant camel chymosin is created [33]. Studies that recently assessed the usage of camel chymosin to produce soft white cheese from camel milk discovered that chymosin when combined with other ingredients improves cheese yield [34, 35].

The effect of camel chymosin on coagulation and preparation of soft unripened cheese made from camel milk has been studied by employing three levels of camel chymosin concentrations (40, 70, and 100 IMCU/L) and two levels of cooking (cooked and uncooked curd) [35]. The shortest gelation time was reported for camel chymosin concentration of 100 IMCU/L and 70 IMCU/L, whereas the highest maximum gel firmness was observed for camel chymosin level of 40 IMCU/L. In this study, it was found that highest cheese yield was observed for uncooked cheese at 100 IMCU/L coagulant level. In this investigation, it was discovered that raw cheese with a coagulant level of 100 IMCU/L produced the largest amount of cheese. Protein, total solids, ash, and hardness were considerably higher in cooked cheese prepared with 100 IMCU/L. Protein, total solids, ash, and hardness were considerably higher in cooked cheese prepared with 100 IMCU/L. On the other hand, 40 IMCU/L cooked cheese received higher ratings for color, texture, and aesthetics. However, the cooked cheese prepared with 70 IMCU/L received the greatest rating for taste, scent, and acceptability. It was determined that heating camel milk curd and employing medium-level chymosin concentration (70 IMCU/L) could be effective methods for producing soft and unripened cheese from camel milk [35].

Another study examined the protein degradation, rheological characteristics, sensory characteristics, and aroma profile of soft brined cheese made from camel milk over a ripening period of 60 days using two levels of brine (2% or 5% NaCl, w/w) and two levels of coagulant (camel chymosin) [55 and 85 International Milk Clotting Units (IMCU)/L] [6]. The finding showed that when cheese ripened and coagulant levels rose, casein degradation in soft brined camel milk cheese increased. With rising levels of salt and moisture in the cheese during ripening, Young’s modulus and stress at fracture rose. However, cheese prepared with 85 (IMCU)/L coagulant had a softer texture and absorbed more salt. The experimental cheeses were described as salty, sour, and hard using descriptive sensory analysis. The amount of coagulant, NaCl content, and ripening duration all have an impact on the volatile fragrance molecules produced in soft-ripened camel milk cheese [6].

3.2 Plant source rennet enzymes

Recombinant enzymes are unpopular in some countries due to religious matters and diets. Additionally, the decreasing supply and rising cost of calf rennet, along with the rising demand for cheese on a global scale, have prompted researchers to look at alternative clotting enzymes that could take the place of traditional rennet in the cheese-making process. Furthermore, different rennet alternatives have emerged as a result of religious considerations and those connected to the vegetarianism of some consumers [36, 37]. Due to the difficulty in producing cheese of a high enough quantity and quality from camel milk, research on plant-based coagulants has been conducted recently to investigate potential substitutes for rennet enzymes. Several milk-clotting enzymes produced from plants are now used in cheese making. Many attempts have been made to contrast their effects with those brought on by animal rennet in terms of the rheological and sensory characteristics of cheese. However, due to their strong proteolytic activity, which aids in the formation of a bitter flavor, vegetable coagulation enzymes are still only partially suited for cheese making [37].

Plant proteases have been divided into groups based on the hydrolytic process mechanism: aspartate, serine, and cysteine proteases [38]. Studies conducted on plant source coagulants such as Zingiber officinale extracts [39], cysteine proteases isolated from Ficus carica [40], and aspartic proteases from Withania coagulans [41] have been used in camel milk cheese production and the resultant cheeses were found acceptable.

The study carried out on the clotting activity of camel milk using ginger rhizome (Zingiber officinale) crude extracts (GCE) reported that GCE would result in strong coagulation of camel milk [39]. According to the finding of this study, the camel milk’s clotting activity (MCA) was highest at pH 5.0, 65°C, and 10% crude extract by volume of milk, while pH 4.5, 55°C, and 40% GCE by volume of camel milk produced the lowest value. According to a study on the clotting activity of camel milk using crude extracts of ginger (Zingiber officinale), camel milk will strongly coagulate when using GCE [39]. According to the report, the highest camel milk clotting activity (MCA) was noted at pH 5.0, temperature 65°C, and crude extract concentration of 10% by volume of milk, while the lowest value was noted at pH 4.5, temperature 55°C, and GCE concentration of 40% by volume of camel milk.

The experiment conducted by fractions of latex protease from Ficus carica on camel milk-clotting properties for use as rennet alternatives revealed that latex fractions, extracted from the fig tree, have a proteolytic activity of 23491.24 IU LG1 (Ficus carica), showed proteolytic and milk-clotting activity. Ficus carica latex protease, which may coagulate milk after production, can be utilized as an alternative to commercial animal chymosin in the cheese-making process. The amount of cheese produced at various enzyme doses was evaluated, and it was discovered that 1mL of the enzyme extract in 100 mL of camel milk produced 15% of the cheese [40].

The effects of camel chymosin and Withania coagulans extract on camel and bovine milk cheeses were performed on cheese’s yield and hardness [41]. The result showed that pure Withania extract exhibited the lower coagulating effect resulting in cheeses with low yield, hardness, fat, protein, and total solids compared to camel chymosin. It was concluded that Withania coagulans extract protease alone is not sufficient to produce good quality cheese, especially camel milk cheese but a mixture of W. coagulans and camel chymosin produced better quality camel and bovine milk cheeses than chymosin alone [41].

In a comparison of the effects of camel chymosin and Withania coagulans extracts on the yield and textural quality of camel milk and bovine milk cheeses, it was discovered that camel milk had a longer gelation time and softer cheese than bovine milk [41]. This study demonstrated that higher moisture entrapment, which lowered cheese hardness, consistently resulted in better yields of unripened camel milk cheese generated by chymosin or the Withania extracts than that of bovine milk cheeses. This study also showed that optimal camel milk as well as bovine milk cheese hardness was obtained by clotting the milk with mixtures of Withania extracts and chymosin suggesting some synergistic interactions, an effect that deserves further investigations.

3.3 Effect of acid coagulants on camel milk cheese making

Acidification is an established process commonly used in combination with heat treatment or rennet addition to prepare fermented milk products (yogurt) and acid-fresh cheeses [42]. The foundation for a huge variety of cultured dairy products is the acid coagulation of milk. By lowering their charge, dissolving part of the insoluble calcium phosphate crosslinks, and altering internal protein bonds, acidification has a direct impact on the stability of casein micelles. At some crucial point, when electrostatic repulsion is diminished and is unable to repel attractive forces, such as hydrophobic contacts and aggregates, eventually gels begin to develop. Acid-induced milk gels become more rigid over time as a result of continuing casein particle-to-casein link formation inside the network.

Cheese prepared from camel milk by direct acidification of milk and by adding starter culture of lactic acid bacteria was evaluated. When starter culture was added to milk to coagulate it, a larger cheese yield was obtained than when cheese was made directly by acidification. Additionally, the starting culture-made cheese contained more total solids, protein, and fat. It was suggested that camel milk can be used to make cheese by coagulating it with starting culture [11]. Another study conducted on the effect of starter cultures on camel milk cheese properties revealed that camel milk treated with nonaromatic cultures such as STI-12, RST-743, and R-707 (see Table 1) for SWC manufacture showed a rapid acidification rate and formation of appreciable fine curd properties. As a result, camel milk SWC made using nonaromatic cultures gave better curd firmness, cheese compositional quality, and texture [12].

4. Effect of camel milk fortification on cheese making

Camel milk presents a high nutritional value and plays a key role in providing milk of superior quality (e.g., more vitamin C and minerals (e.g., K⁺, Cu²⁺, and Mn²⁺)) and essential and polyunsaturated FAs than CM [43]. It is also believed to possess abilities to treat chronic illnesses [44]. The demand for dairy products made with camel milk has grown over the past ten years, and large-scale commercial production of camel milk from contemporary camel farms is expanding. Many milk and dairy products are now produced and sold in Mauritania and the United Arab Emirates, including pasteurized milk, milk powder, fermented liquid milk, and cheese. Due to its coagulation qualities, camel milk is only occasionally used in processed food items and does so with certain challenges [44, 45, 46]. As discussed above, under natural circumstances, making cheese from camel milk is a challenging process because of two primary aspects: the low concentration of κ-casein and the larger micelle sizes compared to cow milk cheese. Cheeses made from camel milk typically have a weak curd and a fragile diverse structure following coagulation [5, 9, 13]. As a result, various methods for strengthening the cheese structure were investigated by combining camel milk with bovine milk.

Shahein et al. [47] were likely the first group to investigate the feasibility of producing soft pickled cheese by combining camel milk with bovine milk in various ratios. According to the scientists, increasing the amount of bovine milk added to camel milk led to higher total solids, fat, and protein levels, whereas moisture and ash content decreased. When camel and cow milk were combined to make a white Sudanese cheese called Jibna-beida (1 camel milk: 1 cow milk, v/v), Siddig et al. [48] discovered identical results. They also identified variations in the Ca²⁺, Na⁺, and K⁺ mineral contents of cheeses. Furthermore, the examination of the ash content in mixtures demonstrated an increase when compared to pure camel milk cheese. However, protein and lactose levels decreased in cheese containing cow milk compared to cheese produced with pure camel milk.

According to the research by Siddig et al. [48], the method used to coagulate milk (either 10% citric acid or 5% starter culture) had an impact on the finished cheese’s composition. When faced with pure camel milk cheese, starter cultures coagulation resulted in an increase in fat and total solid contents, whereas citric acid caused a decrease. The mixture (1 camel milk: 1 cow milk cheese) formed following starter cultures coagulation had a relatively higher Ca²⁺ concentration than pure camel milk and the milk mixture (1 camel milk: 1 cow milk cheese) coagulated with citric acid, according to the data regarding mineral content. In contrast, a relative decrease in K+ in pure camel milk was noted when it was compared with cheeses containing both camel milk and cow milk.

Derar and El-Zubeir [45] investigated how soft cheeses would react if camel milk and EM were combined. Prior to manufacturing cheese, they observed that camel milk had a lower compositional level than milk that had been fortified with ewe milk. Additionally, they noticed variations in the whey made from camel milk, ewe milk, and their milk blends, as well as between various milk kinds. They discovered variations in the total solid contents of the cheeses between the samples of 1 camel milk and 3 ewe milk (v/v). However, when compared to normal cheeses, the protein level was the same. Additionally, during storage, variations in the fat content of cheeses manufactured from camel milk, ewe milk, and their mixes were discovered.

When camel milk and cow milk were combined to make cheese, there were discrepancies in the final cheese composition that can be attributed to variations in the initial combination, composition, and coagulation characteristics of camel and cow milk. According to report, casein in particular has a lower total solid content in camel milk coagulum than CM. Additionally, casein micelles from camel milk had greater average sizes (200–500 nm) than those from cow milk (220–300 nm), although fat globule sizes were the opposite. It is known that cheese yield is influenced by the size of the fat globules and the network created within the milk fat globule membrane. The finding of the aforementioned experiments demonstrated that (i) the species origin of the milk and (ii) the manufacturing procedure of the cheese both affect the proximate composition of the finished cheese [43]. Recently, other scholars notified cheese making from cows, buffaloes, goats, sheep, dromedary camels, and donkey’s milk. They found that camel milk, when compared to the milk from the other species, has a similar coagulation time but a less favorable curd-firming process, with lower nutrient recovery and cheese yield. They also explained camel milk requires specific cheese-making conditions and the use of camel chymosin [49].

Technically, making cheese from camel milk is more challenging than making cheese from milk from other domestic dairy animals under the same circumstances. However, success can be obtained by lowering the pH of the milk, adding calcium chloride, and increasing the renneting temperature. In order to standardize camel milk before making cheese, it has been suggested in several studies to use milk that has been ultrafiltrated (UF) retentate. This supplementation has a number of potential advantages, such as increasing the total solids, thereby increasing the yield, facilitating the coagulation process, and improving the organoleptic and rheological properties as well as the nutritional value of the finished cheese. Mehaia [50] has reported on the use of ultrafiltration technology to standardize the total solids of camel milk used to make soft white cheese. It has been demonstrated that milk concentrated by UF produces cheese of high quality (smooth and creamy body), enhances curd stiffness, and has a higher nutritional value due to the end product’s higher protein, fat, calcium, and phosphorus contents.

Desouky et al. [51] have done a research on the impact of fortifying processed cheese sauce with camel milk powder (CMP) on its stability and quality attributes. In this study, the effects of replacing the cheese foundation in the production of processed cheese sauces with highly acceptable quality and sensory qualities with camel milk powder at various percentages ranging from 5 to 15% were examined. Depending on the amount of CMP applied and the storage period at 6 0.5°C for 30 days, all treatments had statistically different characteristics. When compared to the other treatments, whether they were used fresh or during storage, the cheese sauce containing 15% CMP was distinguished by greater viscosity values during the studied time of shearing and displayed larger upward shifting of the flow curve. All cheese treatments had higher ratings and were considered above average by the participants, especially after a 10% increase in the percentage of CMP added. It was recommended that the addition of CMP enhanced the quality characteristics of cheese sauces and might be taken into consideration as a new source to replace cheeses used in processed cheese base blends [51].

To solve the issue that arose when preparing soft white cheese, research was done on the effects of substituting 20 or 30 percent of the camel milk with a milky component, having (BMR) secret code, and supplementing with 1, 2, and 3 percent sweet potato powder (SPP) [7]. According to this study, camel milk fortification with BMR and SPP enhanced the physic-chemical qualities of cheese by lowering the pH value, whey syneresis, and pepsin coagulation time when compared to control cheese. With higher levels of additive usage, yield, titratable acidity, and curd tension all rose. After 30 days of storage, these additions additionally enhanced the total solids, fat, protein, ash, and salt contents as well as the cheese ripening indices and total volatile fatty acid values in treated cheeses. Pure camel milk cheese (the control) and the ones that had been processed had quite different microstructures in terms of the form, homogeneity, compact or open body, and texture of the casein micelles network. Due to variations in the chemical composition, manufacturing processes, and added agents utilized, variations in the size and number of voids or vacuoles and fat globules were also documented. This finding was back in the control cheese’s body and texture, which weakened, loosened, and opened. Moreover, it was suggested addition of BMR and SPP improved greatly the texture profile of cheeses and their technological aspects [7].

5. Conclusions

The gross composition of camel milk is similar to bovine milk; however, the relative composition, distribution, and the molecular structure of the milk components are different. Consequently, manufacturing cheese from camel milk is difficult. The processing of camel milk into cheese through technological innovations was made possible by applied research. Cheeses prepared from camel milk using starter cultures, utilization of camel chymosin, and fortifications of camel milk with ingredients have considerable improvement in some parameters of cheeses. Starter cultures are added to cheese milk for acidification affecting several aspects of the cheese manufacturing process and finally cheese composition through the production of lactic acid, while reducing pH of curds. Employing medium level of recommended chymosin concentration could be effective method for producing cheeses from camel milk. Furthermore, camel milk mixed with other milk types and fortified with milk powder, milk component, and sweet potato powder have substantial acceptance in some properties of cheeses. The suitability of camel milk processing and its associations with nutritional quality have attracted many studies, but more researches are needed to improve the processing parameters and functional properties of camel milk cheeses.

Conflict of interest

Author has no conflicts of interest to declare.