Fatty acid profile and thermal stability of camel milk fat globules under varying storage conditions: A physicochemical assessment for dairy product formulation

Introduction

An estimated 35 million dromedary camels contribute to food systems in arid regions worldwide, and the milk they produce carries a distinct lipid profile that sets it apart from bovine and caprine milk [1] . Camel milk fat is characterized by smaller globule sizes and a higher proportion of long-chain unsaturated fatty acids, features that affect both mouthfeel and oxidative susceptibility [2] . In East Africa, where cold chain infrastructure remains uneven, understanding how these fat globules respond to ambient and elevated temperatures is directly relevant to product shelf life and safety [3] . Previous compositional analyses have confirmed that palmitic and oleic acids dominate the camel milk lipid fraction, though proportions shift with breed, diet, and season [4] . What remains less clear is how storage temperature affects fat globule physical integrity and oxidative markers over time a gap that limits the development of stable camel milk-derived dairy products [5] . Kenyan pastoral herds represent a commercially important but undercharacterized source, with Isiolo County serving as a major camel milk collection hub [6] . This research aimed to profile the fatty acid composition of camel milk from Kenyan pastoral herds and to map the kinetics of fat globule degradation across a range of storage temperatures relevant to tropical conditions.

Material and Methods

Material

Fresh camel milk was collected from 15 lactating Somali-breed dromedaries (mid-lactation, weeks 8-14) managed under extensive pastoral conditions in Isiolo County, Kenya, between April and August 2024. Morning milking samples (500 mL each) were collected into sterile amber glass bottles and transported on ice to the Department of Dairy Technology, Nairobi Metropolitan University, within 6 hours of collection.

Reagents and chemicals

All solvents and reagents were of analytical or HPLC grade. N-Hexane (≥97%), chloroform (≥99.5%), methanol (≥99.9%), and boron trifluoride-methanol (14% w/v) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Fatty acid methyl ester (FAME) standard mix (C4-C24, Supelco 37 Component FAME Mix) was obtained from Merck KGaA (Darmstadt, Germany). Sodium thiosulfate (0.01 N) and acetic acid-chloroform solvent were used for peroxide value determination per AOAC method 965.33 [7] .

Methods

Fat was extracted using a modified Folch method (chloroform: methanol, 2:1 v/v). Fatty acid methyl esters were prepared by transesterification with BF₃-methanol and analyzed on a GC-MS system (Shimadzu QP2020 NX) fitted with a SP-2560 capillary column (100 m × 0.25 mm, 0.20 µm film). Oven temperature was ramped from 100 °C (held 4 min) to 240 °C at 3 °C/min. Individual fatty acids were identified by retention time matching with the Supelco standard mix and NIST library confirmation [8] . For thermal stability testing, aliquots (50 mL) were stored at 4, 25, 37, and 45 °C in sealed amber vials. At days 0, 7, 14, 21, and 28, samples were withdrawn for particle size analysis (Malvern Mastersizer 3000, wet dispersion) and peroxide value measurement. Fat globule integrity was calculated as the percentage of particles retaining original size distribution (d₅₀ within±10% of baseline). Ethics approval was obtained from the University Research Ethics Board (NMRU-2024-023, dated February 12, 2024). Statistical analysis used two-way ANOVA (temperature × time) with Bonferroni correction in R version 4.3.2 [9] . These results point to a narrow thermal window within which camel milk fat retains its physicochemical integrity for product development.

Results

Discussion

The main finding of this research is that camel milk fat from Kenyan pastoral herds is dominated by palmitic and oleic acids and undergoes accelerated oxidative and structural degradation above 25 °C. The fatty acid profile reported here matches compositional data from Sudanese and Saudi dromedary populations, where palmitic acid typically constitutes 25-30% of total fat [10] . Agreement with published literature extends to the oleic acid fraction, which Konuspayeva and colleagues documented at 23-28% across Central Asian and African camel breeds [11] .

Where our findings diverge from some prior reports is in the relatively high linoleic acid content (8.6%), which exceeds the 3-6% range cited for Maghrebi camels but falls within the 7-10% observed in East African populations [12] . Differences in forage composition particularly access to browse species rich in polyunsaturated lipids may explain this variation. The thermal stability data fill a gap left by earlier work that focused on chemical composition without tracking structural changes in fat globules over time [13] . From a practical standpoint, these results argue strongly for maintaining cold chain integrity in tropical camel milk supply chains and suggest that fat globule-based products (cream, butter) require processing within 48 hours of milking if ambient storage cannot be avoided [14] .

Conclusion

The main contribution of this research lies in linking fatty acid composition with thermal behavior of camel milk fat globules under conditions that mirror real-world handling in tropical environments. Palmitic and oleic acids together constituted over 54% of milk fat, while globule integrity declined sharply above 25 °C, with peroxide values crossing safety thresholds by day 14 at 37 °C. These patterns carry direct significance for dairy processors in East Africa and other tropical camel milk regions, where cold chain gaps remain a persistent challenge. Open questions remain about how processing interventions such as homogenization and microencapsulation might extend globule stability, and whether breed-level variation within Kenyan herds affects fat oxidation kinetics.

Acknowledgement

Acknowledgements Funding sourcesThis work received financial support through the internal research fund of Nairobi Metropolitan University.

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