Coconut chips, a crunchy and nutritious snack loved worldwide, face significant challenges in production, particularly in balancing efficient drying with nutrient preservation.

Table of Contents

The research compared traditional methods like hot air drying (HAD) with advanced approaches such as infrared drying (IRD) and infrared-assisted hot air drying (IRHAD).

The results revealed that IRHAD outperforms other methods, offering faster processing, superior nutrient retention, and enhanced physical properties.

The Limitations of Traditional Drying Methods in Coconut Chip Production

Producing high-quality coconut chips traditionally relies on hot air drying (HAD), a method that uses heated air to remove moisture. While HAD is widely used, it has notable drawbacks.

For instance, drying times can stretch to 135–150 minutes for thin slices, leading to energy inefficiency. Additionally, prolonged exposure to heat often degrades nutrients like proteins, fats, and antioxidants, reducing the snack’s nutritional value.

Another issue is non-uniform drying, which causes inconsistent texture and color, making the final product less appealing. Solar drying, another conventional method, depends heavily on weather conditions and often produces low-quality chips with uneven moisture levels.

These limitations have driven researchers and manufacturers to explore advanced technologies like infrared drying (IRD) and infrared-assisted hot air drying (IRHAD), which promise faster processing and better quality control.

How the Study Evaluated Different Drying Techniques for Coconut Chips

The study began by preparing fresh coconut kernels from 9- to 10-month-old coconuts, sliced into two thicknesses: 0.5 mm and 1.4 mm.

These slices underwent osmotic dehydration, a pretreatment where they were soaked in a 45°Brix sugar solution containing salt and vanilla essence. This step not only enhanced flavor but also reduced drying time by removing excess moisture.

The researchers then tested three drying methods at 65°C: hot air drying (HAD), infrared drying (IRD), and infrared-assisted hot air drying (IRHAD). The goal was to identify the most efficient method for producing coconut chips with optimal texture, nutrient content, and shelf life.

Infrared-Assisted Hot Air Drying Delivers Unmatched Efficiency

Among the three methods, IRHAD emerged as the clear winner in terms of drying speed. For 0.5 mm thick coconut chips, IRHAD completed the process in just 90 minutes, compared to 105 minutes for IRD and 135 minutes for HAD.

Similarly, 1.4 mm thick chips dried in 120 minutes with IRHAD, while IRD and HAD required 135 and 150 minutes, respectively.

This time reduction is attributed to IRHAD’s dual heating mechanism infrared radiation penetrates the coconut slices to heat them internally, while hot air convection removes surface moisture.

This combination skips the slow constant rate drying phase seen in HAD, where moisture evaporates only from the surface, and directly targets thefalling rate phase, where internal moisture migrates outward. As a result, IRHAD cuts drying time by 33–50% compared to traditional methods.

Mathematical Models Confirm IRHAD’s Superior Drying Kinetics

To validate their findings, the researchers analyzed drying data using seven mathematical models. The Diffusion Approximation model provided the best fit for IRHAD, with a near-perfect coefficient of determination (R² = 0.9998 for 0.5 mm chips and 0.9997 for 1.4 mm chips).

This model accounts for both internal and external moisture movement, making it ideal for describing IRHAD’s rapid and uniform drying process.

Statistical metrics like root mean square error (RMSE) and chi-square (χ²) further confirmed the model’s accuracy, with values as low as 0.0054 and 0.0002, respectively. These results highlight IRHAD’s reliability and consistency, essential for industrial applications.

IRHAD Preserves Physical Quality Better Than Conventional Methods

Physical properties like rehydration ratio and hygroscopicity are critical for consumer appeal. Rehydration ratio measures how well dried chips regain moisture when soaked, indicating minimal cellular damage.

IRHAD achieved a rehydration ratio of 2.01% for 0.5 mm chips and 1.69% for 1.4 mm chips, outperforming HAD’s 1.43% and 1.42%, respectively.

Hygroscopicity, or the tendency to absorb ambient moisture, was higher in IRHAD-dried chips (5.43% for 0.5 mm and 2.02% for 1.4 mm) due to their lower final moisture content.

While this might seem counterintuitive, lower moisture levels actually reduce spoilage risks, ensuring longer shelf life. In contrast, HAD-dried chips retained more moisture (3.07% for 0.5 mm and 1.98% for 1.4 mm), making them prone to sogginess over time.

Nutrient Retention: IRHAD Outshines Traditional Drying Techniques

One of the study’s most significant findings is IRHAD’s ability to preserve macronutrients. For 0.5 mm chips, IRHAD retained 43 g/100g of carbohydrates, 4.87% protein, and 36.20% fat, compared to HAD’s 29.97 g/100g carbohydrates, 4.00% protein, and 21.40% fat.

Similar trends were observed in 1.4 mm chips, with IRHAD preserving 45.33 g/100g carbohydrates, 5.32% protein, and 46.35% fat, versus HAD’s 27.23 g/100g carbohydrates, 4.75% protein, and 43.52% fat.

These differences stem from IRHAD’s shorter drying times, which minimize heat-induced nutrient degradation. For example, proteins denature less, and fats oxidize slower under rapid drying conditions, ensuring the final product retains its natural goodness.

Antioxidant Preservation Makes IRHAD-Dried Chips a Healthier Choice

Antioxidants like phenolic compounds are vital for neutralizing free radicals and promoting health.

The study measured total phenolic content (TPC) using the Folin-Ciocalteu method, revealing that IRHAD-dried chips contained 3.89 mg gallic acid/100g (0.5 mm) and 3.42 mg gallic acid/100g (1.4 mm), far exceeding HAD’s 0.91 mg and 0.82 mg.

DPPH radical scavenging activity, which tests antioxidant capacity, showed IRHAD-dried chips neutralizing 34.51% (0.5 mm) and 39.38% (1.4 mm) of free radicals, compared to HAD’s 9.70% and 15.40%.

Similarly, FRAP assays confirmed IRHAD’s superiority, with values of 0.97 and 0.96 trolox equivalents/100g, versus HAD’s 0.17 and 0.49. These results position IRHAD-dried coconut chips as a functional snack with enhanced health benefits.

The Science Behind IRHAD’s Success in Coconut Chip Drying

IRHAD’s effectiveness lies in its hybrid heating mechanism. Infrared radiation directly energizes water molecules inside the coconut slices, causing rapid internal heating.

Simultaneously, hot air convection sweeps away surface moisture, preventing overheating and ensuring uniform drying.

This synergy eliminates the prolonged constant rate phase seen in HAD, where moisture evaporates slowly from the surface, and accelerates the falling rate phase, where internal moisture moves outward.

By skipping the slowest drying phase, IRHAD drastically reduces processing time while preserving cellular structure and nutrients.

Industry Implications: Why Manufacturers Should Adopt IRHAD

For snack manufacturers, adopting IRHAD offers multiple advantages. First, shorter drying times translate to lower energy costs and higher production rates.

Second, the method’s ability to retain nutrients and antioxidants aligns with growing consumer demand for functional, health-conscious snacks. Third, IRHAD-dried chips boast superior texture and color, enhancing market appeal.

A 2022 study on turmeric slices by Jeevarathinam et al. supports these benefits, showing IRHAD achieved 25.22% drying efficiency at 70°C, mirroring the coconut chip findings.

As the food industry shifts toward sustainable and efficient technologies, IRHAD stands out as a game-changer for coconut chips and beyond.

Future Research Directions and Scaling Challenges

While the study’s results are promising, scaling IRHAD for industrial use requires further research. For example, energy consumption comparisons between IRHAD, HAD, and freeze-drying are needed to assess cost-effectiveness.

Additionally, testing IRHAD on other high-moisture foods like fruits, vegetables, and meats could broaden its applications.

Researchers also emphasize optimizing process parameters, such as air velocity and infrared power, for different products. Addressing these challenges will ensure IRHAD’s successful transition from lab-scale trials to large-scale production.

Conclusion

In conclusion, infrared-assisted hot air drying (IRHAD) revolutionizes coconut chip production by addressing the limitations of traditional methods. With drying times reduced by 33–50%, superior nutrient retention, and enhanced physical properties, IRHAD offers manufacturers a cost-effective solution for producing premium-quality snacks.

Consumers, in turn, gain access to healthier, crispier coconut chips rich in antioxidants and natural flavors. As research continues to refine this technology, IRHAD is poised to become the gold standard not only for coconut chips but for dried foods across the industry.

Power Terms

Infrared-assisted hot air drying (IRHAD): A food drying method that uses both infrared heat waves and circulating hot air simultaneously. The infrared waves penetrate deep into the food to drive out internal moisture, while the hot air removes surface moisture. For example, in coconut chip production, this combination dries food faster and more evenly than either method alone. (antonym: conventional hot air drying)

Antioxidants: Natural substances that prevent or slow damage to cells caused by unstable molecules called free radicals. Found in many foods including coconut, these compounds help maintain health and prevent food spoilage. The study showed IRHAD preserved significantly more antioxidants in coconut chips compared to traditional drying methods. (antonym: oxidants)

Phenolic compounds: A specific class of antioxidant chemicals naturally present in plant foods. These substances contribute to the color, flavor, and health benefits of foods like coconut. The research found that the IRHAD method maintained 327% more phenolic compounds in dried coconut chips than conventional drying. (antonym: non-phenolic compounds)

Nutrient retention: The ability of a food processing method to preserve vitamins, minerals, and other beneficial components. Poor processing can destroy heat-sensitive nutrients. The IRHAD technique demonstrated superior nutrient retention in coconut chips by reducing exposure to damaging heat. (antonym: nutrient loss)

Moisture content: The percentage of water present in a food material. Proper moisture removal is essential for creating shelf-stable dried foods. The study carefully monitored moisture content to determine when coconut chips reached the ideal dryness level using different drying methods. (antonym: dryness)

Energy efficiency: The measure of how effectively a system converts input energy into useful output. In food drying, more energy-efficient methods accomplish the same task using less electricity. IRHAD proved more energy efficient than conventional drying by completing the process in significantly less time. (antonym: energy waste)

Drying kinetics: The scientific study of how moisture moves out of food during the drying process, including the rate and pattern of moisture loss. Researchers analyze drying kinetics to optimize food processing methods, as was done in comparing IRHAD to traditional drying for coconut chips. (antonym: moisture absorption)

Heat transfer: The movement of thermal energy from one place to another. In food drying, heat can transfer through conduction (direct contact), convection (through air), or radiation (infrared waves). IRHAD uniquely combines convective and radiative heat transfer for more effective drying. (antonym: heat insulation)

Food preservation: The process of treating and handling food to stop or slow down spoilage while maintaining nutritional value and safety. Drying is one of the oldest food preservation methods, with IRHAD representing a modern improvement that better maintains food quality. (antonym: food spoilage)

Snack food industry: The sector of food manufacturing that produces ready-to-eat snack products like chips, nuts, and dried fruits. This global industry constantly seeks improved processing methods like IRHAD to create better quality products more efficiently. (antonym: fresh food market)

Mature coconuts: Fully developed coconuts that have reached their maximum size and nutritional content. Researchers used mature coconuts in the study because they provide more flesh and have different drying characteristics than young, green coconuts. (antonym: young coconuts)

West Coast Tall variety: A specific cultivar of coconut palm grown primarily in India’s coastal regions. The researchers selected this variety for their experiments to ensure consistency in their tests of different drying methods. (antonym: hybrid varieties)

Blanching: A food preparation technique involving brief exposure to boiling water or steam. The study blanched coconut slices before drying to inactivate enzymes that could cause undesirable changes during storage. (antonym: raw processing)

Osmotic dehydration: A pretreatment method where food is soaked in concentrated solutions (typically sugar or salt) to remove some moisture before final drying. The researchers used this technique to enhance the coconut chips’ sweetness and texture. (antonym: natural dehydration)

Thin-layer drying: A food drying approach where products are arranged in single layers to ensure uniform exposure to drying conditions. The study tested coconut slices of two different thicknesses (0.5mm and 1.4mm) in thin-layer drying setups. (antonym: bulk drying)

Rehydration capacity: A measure of how well dried food can regain moisture when placed in water. This property indicates product quality, with IRHAD-treated coconut chips showing better rehydration capacity than conventionally dried ones. (antonym: dehydration capacity)

Fat content: The proportion of natural oils present in a food material. Coconuts are naturally high in healthy fats, and the study found IRHAD better preserved these fats (69% more retained) compared to traditional drying. (antonym: lean content)

Protein preservation: The maintenance of protein quality and quantity during food processing. Heat can damage proteins, but IRHAD’s efficient drying better protected the protein content of coconut chips in the study. (antonym: protein denaturation)

Color retention: The ability of a food processing method to maintain the original color of the food product. IRHAD-treated coconut chips showed better color retention than those processed with conventional methods, making them more visually appealing. (antonym: color degradation)

Texture profile: The complete set of physical characteristics that define how a food feels in the mouth, including crispness, chewiness, and hardness. IRHAD produced coconut chips with more desirable and consistent texture profiles than conventional drying. (antonym: texture inconsistency)

Operating costs: The ongoing expenses required to run a production process or business operation. While IRHAD equipment has higher initial costs, its energy efficiency may lead to lower long-term operating costs for food manufacturers. (antonym: capital costs)

Scale-up testing: The process of transitioning a laboratory-proven method to full industrial production. The promising IRHAD results now need verification in large-scale factory conditions before widespread commercial adoption. (antonym: lab-scale testing)

Shelf life studies: Research conducted to determine how long a processed food product maintains its quality and safety during storage. Future studies need to confirm whether IRHAD’s quality advantages translate to extended shelf life for coconut chips. (antonym: freshness testing)

Environmental impact: The effect that a process or product has on the natural environment. While not yet studied for IRHAD, its energy-efficient design suggests potential environmental benefits compared to conventional drying methods. (antonym: environmental benefit)

Hybrid technology: A system that combines two or more different technologies to achieve superior results. IRHAD’s success demonstrates how combining infrared and hot air drying can create a solution better than either method alone. (antonym: single technology)

Reference:

Pandiselvam, R., Krishnan, R., Manikantan, M.R. et al. The influence of infrared assisted hot air drying on quality of coconut chips. Food Measure 19, 2611–2623 (2025). https://doi.org/10.1007/s11694-025-03134-8

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