Development of vacuum-fried jackfruit chips with reduced oil content

Introduction

How can a fried snack deliver the texture consumers expect without the health penalties of excessive oil? This question drives much of the current research in frying technology, and vacuum frying is among the most promising answers [1] . By lowering the pressure around the frying vessel, the boiling point of water drops from 100°C at atmospheric pressure to approximately 46°C at 10 kPa allowing frying to proceed at temperatures well below those used in conventional fryers [2] . Jackfruit is the world's largest tree-borne fruit, with annual production exceeding 3 million tonnes, concentrated in South and Southeast Asia [3] . Ripe jackfruit bulbs contain 18-25% carbohydrates, 1.5-2.0% protein, and a distinctive aroma attributed to volatile esters and terpenes [4] . But the fruit is highly perishable, with a post-harvest life of only 3-5 days at ambient temperature. Converting surplus jackfruit into shelf-stable chips would reduce waste and create value for smallholder growers [5] . Atmospheric frying of jackfruit typically produces chips with 28-40% oil on a dry-weight basis [6] , which is comparable to potato chips but inconsistent with growing consumer demand for reduced-fat snacks. Vacuum frying addresses this by reducing oil uptake through two mechanisms: lower surface temperature limits the damage to cell walls that allows oil penetration during cooling, and the rapid pressure release at the end of frying expels oil from the chip surface [7] . This research compared vacuum and atmospheric frying of jackfruit slices at seven temperatures (80-110°C) and characterised the resulting chips for oil content, texture, colour, and sensory quality [8] .

Material and Methods Instrumentation and Analytical Equipment

Comprehensive interpretation

Vacuum-fried chips at 90°C scored highest for overall acceptability (8.1/9), combining good colour retention (L* = 62.1, golden-yellow appearance), adequate crispness (score 8.0), and low perceived oiliness. Atmospheric-fried chips at 90°C scored only 6.4 overall, dragged down by dark colour (L* = 47.3) and greasy mouthfeel. The 80°C vacuum treatment preserved colour best but was scored lower for crispness (6.8), as the chips were slightly chewy due to higher residual moisture (4.8%). Peroxide values after 30 days of storage at 25°C remained below 5 meq O₂/kg fat in all vacuum samples, indicating acceptable oxidative stability.

Discussion

The 60.3% oil reduction at 90°C vacuum versus atmospheric frying is consistent with data reported for vacuum-fried banana chips (50-60% reduction) by Dueik and Bouchon [7] and for vacuum-fried apple slices (55-65%) by Mariscal and Bouchon [9] . Two mechanisms account for the lower oil uptake: first, the intact cellular structure under low-temperature frying limits the capillary pathways through which oil penetrates during the cooling phase; second, the sudden pressure release when vacuum is broken at the end of frying pushes residual surface oil away from the chip [2] . Colour preservation under vacuum is a direct consequence of the lower frying temperature. Maillard reactions and caramelisation are highly temperature-dependent; at 90°C their rates are a fraction of those at 160-180°C used in conventional frying [10] . The golden-yellow hue (L* = 62.1, b* = 28.7) is desirable for jackfruit products, where consumers associate deeper colour with over-processing. From a market standpoint, a jackfruit chip with 11.4% oil could carry a 'reduced fat' label under most regulatory frameworks, which typically require at least 25% less fat than a standard reference product [11] . Given that atmospheric-fried jackfruit chips (28.7% oil) would be the reference, the 60.3% reduction easily qualifies.

Cost analysis and economic feasibility

The main cost difference between vacuum and atmospheric frying lies in equipment. A 50 L commercial vacuum fryer costs approximately Rs 12-15 lakh compared to Rs 2-3 lakh for a conventional fryer of equivalent capacity. However, oil savings (60% less oil consumed per kg of product) and the ability to command a premium price for 'reduced-fat' chips can offset the capital difference within 18-24 months at production volumes of 100 kg chips/day. Energy consumption for the vacuum pump adds roughly Rs 1.2/kg product. A preliminary cost estimate places the production cost of vacuum-fried jackfruit chips at Rs 380/kg versus Rs 310/kg for atmospheric, with a potential retail price of Rs 600-800/kg for the vacuum product in premium snack markets.

Conclusion

Vacuum frying at 90°C and 10 kPa produced jackfruit chips with 60.3% less oil than atmospheric frying, superior colour retention, and the highest sensory acceptability score among all tested conditions. Oil content of 11.4% (dry basis) qualifies the product for 'reduced fat' labelling. Crispness was comparable to conventional chips, and oxidative stability was adequate for at least 30 days at 25°C. The 90°C vacuum condition offers the best balance of quality attributes and is recommended for commercial-scale production of low-oil jackfruit chips. Further work should explore pre-treatments (osmotic dehydration, blanching protocols) to further reduce oil uptake and extend shelf life beyond 30 days.

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