Processing, cooking, and cooling affect prebiotic concentrations in lentil (Lens culinaris Medikus)

• Modest RFO reductions were observed with cooking, cooling, and reheating.
• Resistant starch was higher in green lentil than in red and increased with cooling.
• Lentil cooling process induced synthesis of RS from gelatinized starch.
• Our results show the impact of lentil processing on nutritional quality.

Lentil is an important staple food crop in many regions and is a good source of protein and various micronutrients. Lentil also contains raffinose family oligosaccharides (RFO), resistant starch (RS), and other prebiotic compounds essential for maintenance of healthy gastrointestinal microflora. However, there is a lack of information about concentrations of prebiotics in commercially available, cooked, and processed lentil market classes. This study assessed concentrations of RFO and RS in two commercially available lentil market classes (medium green and small red) and determined changes associated with dehulling, cooking, cooling, and reheating. Mean total RFO concentrations ranged from 5.5 to 6.1% in raw lentils. Total RFO concentration decreased from raw to reheated seeds in two of the four lentil products: whole red (6.1–4.9%) and whole green (5.5–4.3%). Mean RS concentrations in raw, cooked, cooled, and reheated lentil (3.0, 3.0, 5.1, and 5.1% (dry weight), respectively) clearly demonstrate cooling-induced synthesis of RS from gelatinized starch. These results highlight the impact and importance of processing techniques on lentil nutritional quality for both consumer and food industry use.