Process optimization and utilization of resistant starch from banana.

Abstract

Banana (Musa spp.), often hailed as the common man’s fruit, holds a special place in the scenario of agriculture and nutrition, besides having immense economic significance in India and across the globe. Banana, known for its year round availability, affordability, and rich nutrient profile, has transitioned from a commonly consumed fruit to a functional ingredient of growing interest in modern health and food industry. Resistant starch (RS) found in unripe green banana is a promising bioactive compound with potential health benefits. India is leading the global banana production, hence there lies untapped potential in harnessing banana starch, especially its resistant form, for the development of value added food products. However, native banana starch faces limitations in its functional properties, which can be effectively addressed through modification techniques such as Heat Moisture Treatment (HMT). This approach not only enhances the nutritional and functional quality of banana starch but also paves the way for its incorporation into a wide range of health oriented food formulations. Hence, the current study “Process optimisation and utilisation of resistant starch from banana”, was carried out with the objective of optimising the conditions for resistant starch formation in banana and its quality evaluation. The study also aimed to develop value added products incorporating various proportions of banana resistant starch. The popular GI (Geographical indication) granted Kerala banana variety Chengalikodannendran banana and the worldwide popular Cavendish variety Grand Nainebanana were selected for this study. Starch extracted from their flours yielded 26.89% (Chengalikodan) and 27.40% (Grand Naine), with purity of 88.62% and 89.73%, respectively. Resistant starch content was 20.02% in Chengalikodan and 20.62% in Grand Naine. Starch samples of Chengalikodan and Grand Naine banana were modified by autoclaving at 110℃ and 121℃ with different moisture content (10, 20, and 30 %) at three different time periods (15, 30 and 60 minutes). Resistant starch (RS) content in Chengalikodan banana starch was significantly affected by autoclaving conditions. Maximum RS (25.84%) was observed at 121°C for 30 minutes with 10% moisture. In Grand Naine starch, autoclaving enhanced RS from a control value of 20.62% to a peak of 30.52% (at 121°C for 30 minutes with 10% moisture). Repeated autoclaving and cooling cycles further increased RS in Chengalikodan, which reached 54.56% after four cycles, while Grand Naine peaked to 59.63%. Repeated autoclaving and cooling cycles were applied to the isolated banana starch. As a result of this treatment, RS3 was formed. The presence of RS3 confirms that the modification process was effective. The samples with maximum RS content from Chengalikodan and Grand Naine were selected for further analysis and product development. Two treated banana starch (RS3) samples (Chengalikodan and Grand Naine), along with corresponding flour and isolated starch, were initially analysed for colour index and granular morphology. Morphological analysis showed that flour and isolated starch granules varied in shape, size, and surface texture based on processing. Chengalikodan and Grand Naine flours had irregular, oval, and elongated particles with smooth to rough surfaces, while isolated starch granules were smooth and more uniform. Autoclaving altered native starch structure, forming compact, aggregated granules due to retrogradation, with resistant starch showing larger, fused clusters and rougher surfaces. Chengalikodan flour had higher lightness and whiteness, which decreased isolated starch and treated starch. In contrast, Grand Naine showed consistently lower lightness across all forms, reflecting the impact of processing and variety on visual traits. The physicochemical properties of flour, isolated starch, and autoclaved starch samples from Chengalikodan and Grand Naine banana were evaluated over three months. Autoclaved starch samples of both Chengalikodan and Grand Naine showed higher pH (5.36 and 5.34), moisture (7.08 and 7.02%), water holding capacity (4.91 and 5.00%), and gelatinisation temperature (77.02 and 75.67℃), but lower bulk density (0.48 and 0.51g/ml), swelling power (8.86 and 8.88%), solubility (3.65 and 3.58%), syneresis (27.41 and 28.22%), dispersibility(75.14 and 76.31%), and peak viscosity (487cp and 571cp), which are important properties for the formulation of functional, shelf stable and healthy food products. This study assessed the nutritional, functional, and glycemic characteristics of flour, isolated starch, and treated starch (RS) samples of Chengalikodan and Grand Naine banana. Treated starch had the lowest total soluble solids (2.56 and 2.41ºBrix), with lower total and reducing sugars. Treated starch showed the highest carbohydrate content (87.72 g and 87.33 g/100 g), highest slowly digestible starch (18.88% and 18.59%) and lowest rapidly digestible starch (24.56% and 22.53%) for Chengalikodan and Grand Naine, respectively. It also contained high amylose of 35.42% (Chengalikodan) and 38.92% (Grand Naine) and lower amylopectin. Treated starch showed the lowest in vitro starch digestibility of 44.56% and 40.65% and the lowest glycemic index of 37.56 and 36.65, slightly increasing after three months, for Chengalikodan and Grand Naine, respectively. Instant custard mixes were developed using 10-35% banana resistant starch, 5-35% corn flour, and other ingredients. Both Chengalikodan (T4) and Grand Naine (T10) banana based custard mix with 20% RS had the highest overall acceptability of 8.55 and 8.22 respectively. Control custard mix (T0) had the highest brightness (L* = 83.93) and whiteness (WI = 79.66), while T4 and T10 showed reduced lightness (81.90 and 77.74) and whiteness (77.32 and 74.12). Banana resistant starch mixes had lower initial swelling power, solubility, water absorption capacity, and dispersibility, which declined further during storage. Bulk density and moisture were higher and increased over time. Carbohydrate, protein, and fat contents were initially lower and gradually decreased. Starch content was lower in T4 and T10 (56.21% and 54.95%) than in the control (62.91%). Rapidly and slowly digestible starch were also lower in T4 (57.62% and 10.23%) and T10 (58.23% and 10.25%), while resistant starch was higher (32.15% in T4 and 31.52% in T10) compared to the control. In vitro starch digestibility was lower in T4 and T10 (41.28% and 42.40%) than in the control (62.70%). Vermicelli was formulated using 25-45% resistant starch from Chengalikodan and Grand Naine banana, combined with banana flour and whole wheat flour (30-70%). Vermicelli with 100% refined wheat flour served as control. Sensory evaluation showed that T3 (35% Chengalikodan resistant starch + 15% banana flour + 50% whole wheat flour) scored highest overall acceptability (8.28). Correspondingly, uppuma made from T3 vermicelli also received superior sensory scores, with overall acceptability of 8.42. Products with Grand Naine resistant starch (35% Grand Naine resistant starch + 15% banana flour + 50% whole wheat flour) had slightly lower scores (8.24 for vermicelli and 8.15 for uppuma than Chengalikodan based products, though both were well accepted. The study compared physicochemical, nutritional, and starch digestibility properties of vermicelli made with RS from Chengalikodan and Grand Naine banana to a refined wheat flour control. Banana RS vermicelli had lower lightness and whiteness, with higher moisture content (6.89% in Chengalikodan, 6.95% in Grand Naine) than the control (6.33%). It also had higher carbohydrate and energy content, while protein and fat decreased over storage. Rapidly digestible starch was lower in banana RS vermicelli (41.45% and 43.09%) than the control (84.42%), while slowly digestible starch and RS were higher. Glycemic index was also lower (46.23 in Chengalikodan, 45.55 in Grand Naine) compared to the control (76.23). Instant uppuma mixes were made using Chengalikodan and Grand Naine banana resistant starch vermicelli (35% RS + 15% banana flour + 50% whole wheat flour). Among treatments with varying water volumes, T3 (100g vermicelli with 300 ml water) received the highest sensory scores for both banana varieties. The mixes showed better stability over three months of storage. The production cost of banana flour was ₹ 33/100g (Chengalikodan) and ₹ 19/100g (Grand Naine), while isolated banana starch cost ₹ 34/100g and ₹ 20/100g, respectively. Treated starch production cost was ₹ 23/100g (Grand Naine) and ₹ 37/100g (Chengalikodan). Custard mixes made with banana RS cost ₹ 40/100g (Chengalikodan) and ₹ 36/100g (Grand Naine), while vermicelli and instant uppumamixes with Chengalikodan RS cost ₹ 42/100g and ₹ 54/100g, compared to ₹ 33/100g and ₹ 45/100g for Grand Naine. Banana starch is a promising functional ingredient that can contribute to the development of health enhancing food products. Heat moisture treatment enhances its functional and physicochemical properties, opening new opportunities for health focused applications. This research highlights banana starch as a sustainable, cost effective ingredient with transformative benefits, poised to meet the growing demand for nutritious, innovative food solutions and shape the future of the food industry.