Influence of osmotic dehydration on physico-chemical changes and storage quality of banana slices in Kamalapur Red and Grand Naine varieties

Introduction

Banana (Musa spp.) ranks among the most widely consumed fruits globally, with annual production exceeding 115 million metric tons, making it a crucial commodity for both developed and developing nations (FAO, 2020) [8] . India stands as the largest producer of bananas, contributing approximately 30% of global production, with varieties such as Grand Naine and indigenous cultivars like Kamalapur Red playing significant roles in commercial cultivation (Mohapatra et al., 2010) [33] . Despite their nutritional richness, including high levels of potassium, dietary fiber, vitamins and antioxidants, fresh bananas are highly perishable with moisture content ranging from 70-80%, leading to substantial post-harvest losses estimated at 20-40% in tropical regions (Aurore et al., 2009) [4] . The challenge of preserving banana quality while extending shelf life has driven extensive research into various preservation techniques. Among these, osmotic dehydration has emerged as a promising pre-treatment method that offers advantages over conventional drying processes by better retaining nutritional components, color, flavor and texture International Journal of Advanced Biochemistry Research 2025; SP-9 (12): 697-708 (Rastogi et al., 2002) [23] . This process involves immersing fruit pieces in hypertonic solutions, typically containing sugars or salts, which creates an osmotic pressure gradient facilitating water removal from the fruit tissue while simultaneously allowing solute uptake (Torreggiani & Bertolo, 2001) [35] . The dual mass transfer mechanism not only reduces moisture content but also improves the physico-chemical stability of the final product. Recent studies have demonstrated that osmotic dehydration significantly influences various quality parameters of banana products, including water activity, texture, color retention and overall sensory acceptability (Fernandes et al., 2016) [9] . The effectiveness of this technique depends on multiple factors such as solution concentration, temperature, immersion time, fruit-to-solution ratio and intrinsic varietal characteristics (Azoubel & Murr, 2004) [5] . Different banana varieties exhibit distinct responses to osmotic treatment due to variations in cellular structure, initial sugar content and pectin composition, which directly impact mass transfer kinetics and final product quality (Kaur & Singh, 2016) [12] . Kamalapur Red and Grand Naine represent two commercially important banana varieties with contrasting characteristics. While Grand Naine is widely cultivated for export markets due to its uniform size and extended shelf life, Kamalapur Red is valued for its distinctive flavor and nutritional profile but remains underutilized due to limited processing knowledge (Kumar et al., 2012) [32] . Understanding how osmotic dehydration influences the physico-chemical properties and storage stability of these varieties is essential for developing variety-specific processing protocols and reducing post-harvest losses. This study aims to investigate the comparative effects of osmotic dehydration on quality attributes and storage behavior of banana slices from both varieties, thereby contributing to the optimization of preservation strategies for diverse banana cultivars.

Materials and method

The present investigation on "Development of osmotic dehydrated product from banana" was carried out in the Department of Postharvest Management, College of Horticulture, UHS, Bagalkot, Karnataka during the year 2024-2025. The samples of banana utilized in the current study were obtained from reputed suppliers in a bid to ensure consistency and quality. Two varieties of banana were chosen in the current study and they were Grand Naine (G9) and Kamalapur Red Banana. Physiologically ripe, disease-free and uniformity in colour, size, mature fruits at the edible stage were directly taken from well-maintained orchards in and around Bagalkot district, Karnataka.

Osmosis treatment

Banana slices weighing 1 kg each were immersed in sugar syrup solutions of 50, 60 and 70°Brix at a slice to syrup ratio of 1:2 and allowed to undergo osmosis for 4, 6 and 24 hours at room temperature (20-30°C). At the end of each osmotic period, the slices were removed from the syrup and quickly rinsed with water to eliminate any sugar coating sticking to their surface and then surface dried under fan. The osmosed banana slices were then weighed and recorded in grams.

Dehydration

After osmosis treatment measured amounts of osmosed banana slices were spread arranged on stainless steel trays and placed inside a cabinet tray dryer. The slices were dried thoroughly with warm air at 55-60°C until they attained the target moisture content and quality. The duration required to reach the optimal dryness was noted for each treatment. The laboratory experiment was conducted using a Factorial Completely Randomized Design (Factorial CRD) consisting of 26 treatments, with each treatment replicated twice.

Weight loss of the samples during storage was expressed as a percentage and calculated by recording the initial weight at the beginning of the storage period and comparing it with the weight at each sampling interval.

Initial weight-Weight at time

Initial weight

Moisture loss during storage or processing was determined as a percentage reduction from the initial moisture content. The calculation was based on the difference between the initial moisture and the moisture content recorded at a given time.

Solid gain (%) was estimated to understand the net uptake of solutes during the process. It was calculated by subtracting the percentage weight loss from the percentage moisture loss at each sampling point, using the following expression:

Moisture loss (%) -Weight loss (%) Yield (%) Yield (%) was calculated to assess the amount of usable product obtained after processing. It was expressed as the ratio of the weight of the prepared fruit pieces to the weight of the fresh, unprocessed fruit, multiplied by 100.

Dehydration ratio

The dehydration ratio was calculated to evaluate the extent of moisture removal during the drying process. It was expressed as the ratio of the weight of fresh fruit slices to the weight of the dehydrated slices Dehydration ratio = Weight of fresh slices Weight of dehydrated slices Total soluble solids ( ⁰ Brix) Total soluble solids (TSS) of fresh slices and osmodehydrated slices were recorded using hand refractometer (0-32° Brix). The TSS was expressed as °Brix after making necessary temperature corrections to the recorded readings.

Moisture content was measured using a moisture balance. Two grams of the osmotically dehydrated sample were placed in the sample dish and dried within the electric moisture balance. The device automatically showed the moisture content as a percentage and signaled the completion of the measurement with an audible beep, providing a stable moisture value.

Titratable acidity was determined by titrating a measured aliquot of the sample with standard 0.1 N NaOH using phenolphthalein as the indicator and the results were expressed as a percentage of citric acid.

The lead acetate-free filtrate was prepared following the, Fifty milli liters of this filtrate was taken and 5 ml of concentrated 12N HCl was added, then left overnight to allow slow inversion. After cooling, the acid was neutralized initially with 40% NaOH and later near the endpoint with 0.1 N NaOH using phenolphthalein as an indicator, making the solution slightly alkaline. The volume was then adjusted to 100 ml. This prepared solution was titrated against Fehling's solution to estimate total sugars, with the results expressed as a percentage on a weight basis.

Total sugars % =

Results and Discussion

Effect of pre-treatments on moisture content (%) of osmosed banana slices Significant difference in moisture content among types, with Kamalapur Red (45.56%) outperforming Grand Naine (44.42%). Significant disparities existed across the treatments. T13 exhibited the highest mean moisture content at 51.14 per cent, whereas T8 displayed the lowest at 38.94 per cent. Additional low-moisture regimens included T12 (40.06%) and T10 (41.69%). A notable interaction occurred between V and T. The moisture content in Kamalapur Red varied from 51.90 per cent (T13) to 40.39 per cent (T8), while in Grand Naine, it ranged from 50.38 per cent (T13) to 37.49 per cent (T8). The fresh control (T13) retained the greatest moisture, while the prolonged/high-severity osmotic treatment (T8) produced the driest slices in Table 1.

Osmotic dehydration (OD) extracts water by immersing tissue in a hypertonic solution. To increase the °Brix of the solution, incorporate sodium chloride (NaCl) and prolong the tissue's contact with the solution; this will decrease external water activity and elevate the chemical potential gradient. This accelerates the water's egress, resulting in the tissue retaining less moisture. Consequently, stringent, prolonged schedules (such as T8) yield the minimal moisture, whilst the control (T13), lacking any external osmotic driving force, remains unchanged. Established mechanisms and trends indicate that authoritative reviews and banana-specific kinetic studies consistently demonstrate that moisture loss escalates with increased solution concentration and duration. Furthermore, the presence of NaCl in sucrose exacerbates water removal by diminishing water activity and modifying transport dynamics (Torreggaini, 1993; Yavda and Singh, 2012; Rastogi et al., 2002) [29,34] . Studies that are analogous or corroborative. Mercali et al. 2010 [14] quantified the osmotic pressure and effective diffusivities in bananas. Increased sugar concentrations and the presence of NaCl enhance water loss, resulting in a reduced ultimate moisture content. The initial rapid phase is induced by a significant osmotic gradient, which diminishes when the gradient lessens (Merciali et al., 2010). Mirzayi et al. (2018) [15} employed response-surface designs to demonstrate that water loss increases with the proportion of sucrose, salt and duration. They discovered that moderate quantities of salt can alter the absorption of solids while simultaneously promoting more water drainage, which aligns well with our low-moisture treatments. Comprehensive OD investigations on fruits and vegetables (Torreggiani, 1993; Yadav and Singh 2014; Asghari et al., 2024) [29,3] affirm that solution concentration and exposure duration are the primary determinants of moisture decrease, whereas tissue microstructure (variety) establishes the achievable limits. This elucidates the significant disparity in mean variety and the V×T relationship.

Effect of osmotic pre-treatments on the yield and drying ratio of osmotically dehydrated banana slices

The influence of osmotic pre-treatments on the yield and drying ratio of banana slices shown considerable discrepancies across treatments and kinds as in Table 2. The maximum yield was observed in treatment T13 (control), which excluded osmotic pre-treatment. The outcomes were 28.02 per cent for Kamalapur Red and 28.96 per cent for Grand Naine, resulting in a treatment mean of 21.33 per cent. Treatment T13 exhibited the lowest yield, with 21.77 per cent in Kamalapur Red and 20.89 per cent in Grand Naine. The diminished yield in treated samples relative to the control may be attributed to osmotic dehydration, which resulted in increased solid gain and water loss, facilitating the transfer of soluble solids from the syrup into the fruit tissues and the migration of soluble components from the fruit into the osmotic medium. The drying ratio also altered in the contrary direction. The control samples (T13) exhibited the highest drying ratios, measuring 5.26 for Kamalapur Red and 5.49 for Grand Naine, whereas T12 demonstrated the lowest drying ratios, recorded at 4.24 for Kamalapur Red and 3.44 for Grand Naine. The treated samples exhibited reduced yields due to an increase in solids and a greater loss of moisture, resulting in a bigger ratio of raw to dry weight. The findings demonstrate that osmotic pre-treatments influence both mass transfer mechanisms during dehydration and the recovery of the final product's weight. The present findings correspond with earlier research by Torreggiani (1993) [29] , which shown that osmotic dehydration leads to significant water loss and solid absorption, thereby reducing the final yield while increasing the drying ratio. Similarly, Panagiotou et al. (1999) [18] and Rastogi et al. (2002) highlighted that the improvement of the drying ratio via osmotic treatment is attributable to the reduction in initial moisture content and the incorporation of solutes, hence increasing the dry matter content of the product before hot air drying. Sagar and Kumar (2010) [25] said that osmotic pretreatments enhance product quality; nevertheless, they invariably reduce yield due to the leaching of soluble fruit components.

Effect of pre-treatments on reducing, non-reducing and total sugars in osmotically dehydrated banana slices

The results where illustrated as in the Table 3, 4 and 5. The reduction in sugar throughout treatments varied from 36.96 per cent in T₁₃ (control; 0.1% KMS, 10 min) to 50.82 per cent in T₉ (70°Brix, 24 h), T₁₂ (70°Brix + 1% salt, 24 h; 49.63%), T₁₁ (60°Brix + 1% salt, 24 h; 48.23%), T₈ (60°Brix, 24 h; 47.53%) and T₆ (70°Brix, 6 h; 47.42%) were notable performers. T₁ (50°Brix, 4 h; 42.58%) and T₂ (60°Brix, 4 h; 43.32%) exhibited reduced results, attributable to milder and shorter conditions. Kamalapur red exhibited a range of 37.92 to 51.22 per cent (minimum T₁₃, maximum T₉), while Grand Naine displayed a range of 36.00 to 50.42 per cent (minimum T₁₃, maximum T₉).

The total amounts for each treatment were between 43.25 per cent in T₁₃ (control; 0.1% KMS, 10 min) and 67.73 per cent in T₉ (70°Brix, 24 h). The highest values were T₁₂ (66.43%), T₁₁ (63.21%), T₈ (62.56%) and T₆ (62.23%). The intermediate values were T₅ (59.10%), T₇ (58.81%), T₁₀ (58.13%), T₃ (56.99%) and T₄ (55.03%). The lowest values were T₂ (54.83%) and T₁ (51.60%), while the control (T₁₃) was the lowest. The ranges were big for each type: Kamalapur red: 44.32-68.29 per cent (T₁₃ to T₉); Grand Naine: 42.19-67.17 per cent (T₁₃ to T₉). This illustrates solute absorption and moisture reduction during osmotic dehydration, succeeded by sucrose inversion and the progressive involvement of reducing sugars in nonenzymatic browning within a low-moisture matrix ( [13,22,15,7,11] .

Effect on reducing sugars, non-reducing sugars at 2 MAS

Treatment means went up compared to the first stage. T₁₂ (70°Brix + 1% salt, 24 h; 52.88%) was the highest, followed by T₉ (70°Brix, 24 h; 50.71%), T₈ (60°Brix, 24 h; 50.34%) and T₁₁ (60°Brix + 1% salt, 24 h; 50.04%), T₆ (70°Brix, 6 h) also stayed high at 49.53%. Again, the control group, T₁₃, had the lowest score (36.91%). Effect on non-reducing sugars at 2 MAS Treatment signifies a diminished effect compared to the outset, aligning with the partial hydrolysis (inversion) of sucrose into reducing sugars. The mean for T₉ was 11.47 per cent, succeeded by T₁₂ at 10.98 per cent, T₈ at 10.45 per cent, T₁₁ at 10.22 per cent and T₆ at 10.00 per cent. T₁₀ (9.72%), T₇ (9.60%) and T₅ (9.23%) occupied the intermediate tier. T₃ (8.38%), T₄ (7.66%), T₂ (7.16%) and T₁ (5.52%) had diminished values, whereas the control T₁₃ recorded a value of 4.72 per cent. In comparison to the initial stage, the majority of treatments demonstrated a little reduction in total sugars. The treatment with the greatest mean was T₁₂ (70°Brix + 1% salt, 24 hours; 63.86%). Subsequently, T₉ (70°Brix, 24 h; 62.18%), T₈ (60°Brix, 24 h; 60.79%) and T₁₁ (60°Brix + 1% salt, 24 h; 60.26%) were observed. T₆ (59.53%), T₅ (56.89%), T₇ (56.22%) and T₁₀ (56.03%) occupied the subsequent tier. T₃ (54.87%), T₄ (52.69%), T₂ (51.69%) and T₁ (49.21%) occupied the bottom tier and T₁₃ (41.63%) was the lowest.

Two months subsequent to confinement (2 MAS). The sequence remained unchanged. The quantity of reducing sugars increased further, whereas the level of non-reducing sugars decreased. This occurs when sucrose decomposes during storage. In the rigors programmes, the total quantity of sugars remained elevated compared to the milder schedules and the control group. The significance of variety, treatment and their interaction suggests that, although the intensity-based ranking remains applicable, the extent of change within a treatment is contingent upon the cultivar (Cordenunsi-Lysenko et al., 2019) [7] .

Effect on reducing sugars at 4 MAS

The V, T and V×T effects remained significant after 4 months (CD at 1%: V = 0.08/0.33; T=0.21/0.86; V×T =0.31/1.21). The Kamalapur variety exhibits a percentage of 48.40 per cent, compared to Grand Naine's 45.50 per cent indicating that the varietal advantage persists even after prolonged storage. The optimal treatment mean was T₁₂ (70°Brix + 1% salt, 24 h; 53.52%), followed by T₈ (60°Brix, 24 h; 51.42%) and lastly T₁₁ (60°Brix + 1% salt, 24 h; 50.99%). The subsequent tier consisted of T₅ (60°Brix, 6 hours; 49.17%) and T₆ (70°Brix, 6 hours; 48.81%). The lowest values were seen in T₁₃ (control; 38.16%) and an exceptionally low mean in T₉ (70°Brix, 24 h; 39.05%). In the non reducing sugars The stage-wise treatment means were the lowest across the three time points, indicating that the inversion is ongoing. At 4 MAS, T₉ (7.04%) exhibited the highest mean, closely succeeded by T₁₂ (6.93%), T₁₁ (6.32%) and T₈ (6.52%). Additional upper-mid results were T₆ at 6.20 per cent and T₇ at 6.04 per cent. The middle band comprised T₅ (5.24%), T₄ (4.93%), T₃ (5.00%) and T₂ (4.69%). T₁ (4.11%) and the control T₁₃ (4.05%) constituted the lowest category. Treatment means revealed a bigger drop overall compared to 2 MAS. T₁₂ (70°Brix + 1% salt, 24 h; 60.45%) was the best, followed by T₈ (57.95%) and T₁₁ (57.31%). T₆ (55.02%), T₅ (54.42%), T₇ (54.39%) and T₁₀ (53.22%) were the other upper-mid values. T₁ (48.08%), T₃ (52.37%), T₄ (51.41%) and T₂ (50.48%) were the lowest tier treatments. The control T₁₃ was the lowest at 42.22%. For T₉ at 4 MAS, there was a strange event: Kamalapur red stayed high (62.13%), while Grand Naine fell abruptly to 30.06%, bringing the treatment mean down to 46.09%. This crossover fits with the big V×T phrase at this point. This occurred because of a significantly low Grand Naine value (24.00%) at 4 MAS, despite the high Kamalapur value (54.10%). This outlier aligns with the substantial V×T term. A notable crossover in a rigors schedule highlighted the strong variety × treatment interaction Kamalapur Red stayed increased while Grand Naine decreased demonstrating that different cultivars respond variably to the same treatments. The observed sequential alterations result from the concurrent processes of sucrose inversion and nonenzymatic browning. These mechanisms involve the decomposition of reducing sugars and the formation of brown polymers (Cordenunsi-Lysenko et al., 2019 [7] ; Kathuria et al., 2023) [11] .

Effect of pre-treatments on titrable acidity in osmotically dehydrated banana slices The acidity levels ranged from 0.73 per cent in T₁₃ (control; 0.1% KMS, 10 min) to 1.31 per cent in T₁ (50°Brix, 4 h) across the treatment procedures. T₂ (1.25%), T₄ (1.23%), T₅ (1.22%), T₇ (1.23%) and T₁₀ (1.21%) yielded the highest outcomes. The values in T₃/T₈/T₁₁ (about 1.16-1.17%) and T₆ (1.16%) were moderate. The treated samples exhibited the lowest values in T₉ (1.11%) and T₁₂ (1.12%), while the control T₁₃ recorded the lowest value overall. A diverse array of variants exists: Kamalapur red ranges from approximately 0.81 to 1.48 per cent (minimum T₁₃, maximum T₁), whereas Grand Naine ranges from about 0.66 to 1.14 per cent (minimum T₁₃, maximum T₁), as showed in table 6. In comparison to the outset, the majority of treatments demonstrated a slight reduction in acidity after 2 months. T₁ (1.20%) had the highest treatment mean, followed closely by T₂ (1.17%), T₄ (1.13%), T₇ (1.11%), T₅ (1.10%) and T₁₀ (1.12%). T₁₁ (1.07%), T₈ (1.05%) and T₆/T₉ (about 1.02-1.04%) exhibited intermediate outcomes. T₁₂ reached 1.00 per cent, whereas T₁₃, the control, had the lowest value at 0.67 per cent. Treatment indicates an improvement from 2 MAS. The highest tier included T₁ (1.11%) and T₂ (1.07%), succeeded by T₁₀ (1.05%), T₄/T₇ (about 1.03%) and T₅ (1.04%). T₈/T₁₁ (about 0.97-0.98%), T₃/T₁₂ (around 0.96%) and T₆ (0.93%)/T₉ (0.94%) were situated within a mid-lower range. The control, T₁₃, remained constant at 0.58 per cent. The ranges for several types were: Kamalapur red: 0.71-1.28 per cent (minimum T₁₃, maximum T₁); Grand Naine: 0.46-0.95 per cent (minimum T₁₃, maximum T₁). After four months, the milder pre-treatments (T₁-T₂) exhibit the highest acidity, while the control demonstrates the lowest acidity. More intense osmotic circumstances (elevated °Brix, extended time, ±salt) result in reduced final acidity; hence, Kamalapur red has a distinct acidity advantage over Grand Naine. Initially, at 2 months and 4 months, statistically significant changes in titratable acidity were observed attributable to variety, osmotic pre-treatments and their combination (Table 4). Kamalapur Red consistently exhibited greater acidity than Grand Naine at all stages, attributable to its bigger organic acid reservoir and lower sugar-to-acid ratio at baseline. Consequently, following analogous dehydration histories, the acid percentage remained elevated in Kamalapur Red compared to Grand Naine (varietal impact). The most acidity was observed in the moderate, short exposure (T1) at each step, whereas the least acidity was recorded in the control (T13). Intense schedules (high °Brix ± salt, extended contact) exhibited reduced acidity compared to T1. Numerous research provides substantial evidence supporting the preceding argument. In bananas and other tropical fruits, elevated syrup concentration and prolonged immersion time diminish titratable acidity in the dehydrated product through solute uptake-driven dilution and subsequent acid utilisation during storage: banana (Bongirwar & Sreenivasan, 1977; Pokharkar & Prasad, 1998b; Pokharkar et al., 1997) [6,19,21] , mango (Nanjundaswamy et al., 1978 [17] ; Sagar & Khurdiya, 1999 [25] ; Amitabh et al., 2000 [2] ; Varany Anond et al., 2000 [30] ; Tiwari & Jalali, 2004a) [27] , papaya (Ahmed & Choudhary, 1995) [1] , apricot (Sharma et al., 2004) [26] and pineapple (Pokharkar & Prasad, 1998a [20] ; Tiwari & Jalali, 2004b [28] ). The reduction of acidity during storage has been associated with the transformation of acids, the inversion of sucrose and reactions akin to the Maillard reaction (Sharma et al., 2004) [26] . Recent studies on osmotic dehydration (2018-2024) demonstrate that solution concentration, salt addition and contact duration are primary factors affecting mass transfer and the sugar/acid equilibrium in osmosed fruits. This explains why moderate T1 displayed the maximum acidity, whereas control (T13) and severe OD regimens demonstrated the lowest acidity levels.

Effect of pre-treatments on TSS of osmotically dehydrated banana slices Throughout all stages (Initial, 2 MAS, 4 MAS), both variety (V) and treatment (T) significantly influenced TSS, consistent with osmotic dehydration (OD) theory: conditions exhibiting a more robust osmotic driving force (elevated °Brix, extended contact, ±1% NaCl) resulted in higher TSS, whereas milder or shorter conditions yielded lower TSS.

The analysis indicates that Kamalapur Red consistently shown a significant varietal superiority over Grand Naine at all stages (Δ > CD at 1%), implying that intrinsic composition (baseline solids, sugars, acidity) affected TSS responses to osmotic dehydration. This varietal differentiation aligns with evidence indicating that genotype-induced compositional changes lead to distinct processing and metabolic effects (Rai et al., 2022 [22] ; Haque et al., 2020) [10] . As presented in table 7. TSS exhibited significant variability among treatment means. The highest tier included T₁₂ (67.16%), T₈ (64.39%), T₁₁ (63.68%) and T₆ (61.13%). The middle tier comprised T₅ (60.46%), T₇ (60.43%), T₁₀ (59.13%), T₃ (58.19%) and T₄ (57.13%). The lowest tier comprised T₂ (56.09%) and T₁ (53.43%), but the control, T₁₃, recorded the lowest percentage at 46.91 per cent. The ranges for each type were extensive: Kamalapur red exhibited 47.81-69.03 per cent [15] ; Haque et al., 2020) [10] . The control group (no osmotic dehydration, preservative dip only) had the lowest total soluble solids, indicating the absence of solute impregnation. Most therapy demonstrated an elevation in TSS relative to the initial stage. T₁₂ (70.95%) exhibited the highest treatment mean, after by T₉ (69.09%), T₈ (67.55%), T₁₁ (66.96%) and T₆ (66.15%). The second tier comprised T₅ (63.21%), T₇ (62.46%) and T₁₀ (62.25%). T₃ (60.96%), T₄ (58.84%), T₂ (57.43%) and T₁ (54.68%) constituted the inferior tier. T₁₃, the control, remained unchanged at 46.26 per cent. At 2 MAS, TSS increased further in the majority of osmosed samples and the intensity-based ranking remained consistent: the regimens that exhibited the highest strength at day-0 continued to rank among the top at 2 MAS. This pattern corresponds with the ongoing physicochemical reequilibration in low-moisture slices and the limited starch hydrolysis where sucrose conversion may persist in preserved banana matrices (Aurore et al., 2009 [4] ; Kaur, 2024) [12] . Nevertheless, as osmosed tissues inherently possess elevated solute concentrations from the outset, the subsequent increases during storage are minimal and contingent upon the therapy, thereby preserving the advantages of robust osmotic pressure. The control remained unchanged, indicating that natural ripening in untreated tissues does not compensate for the deficiency of osmotic solute absorptions in these conditions. T₉ (75.26%) exhibited the highest treatment mean at this juncture, succeeded by T₁₂ (73.81%), T₁₁ (70.30%) and T₈ (69.51%). Additional upper-mid results included T₆ (69.15%), T₅ (65.66%), T₇ (65.34%) and T₁₀ (64.59%). The lower means were T₃ (63.32%), T₄ (61.14%), T₂ (60.92%) and T₁ (57 .33%). The control, T₁₃, exhibited the lowest value at 42.22 per cent. At 4 MAS, total soluble solids (TSS) were maximised in the most demanding regimens, especially the high-°Brix, 24-hour, ±salt configuration. Less intensive and abbreviated treatments resulted in a reduced cluster, whereas the control remained the lowest. The stagewise profile Initial < 2 MAS ≤ 4 MAS for robust OD aligns with sustained solids retention in a low-aw, sugar-rich matrix. In instances where TSS stabilised or decreased somewhat, non-enzymatic browning is likely responsible. Over time, reducing sugars engage in Maillard-type reactions, gradually diminishing the quantity of extractable soluble sugars or converting them into brown polymers (Sagar & Khurdiya, 1999; Ahmed & Choudhary, 1995) [24,1] . The results demonstrate that OD regimens with high sucrose concentrations (about 60-70 °Brix), a 24-hour contact duration and a slight NaCl addition confer a TSS benefit on day zero that endures throughout storage (Mirzayi et al., 2018; Haque et al., 2020) [15,10] . The persistent varietal superiority of Kamalapur Red indicates that both internal matrix composition (solids, sugars, acidity) and the intensity of external osmotic dehydration jointly affect the solublesolids trajectories in osmotically dehydrated banana slices (Rai et al., 2022) [22] .

Conclusion

The comprehensive analysis of osmotic dehydration (OD) pre-treatments on banana slices, comparing Kamalapur Red and Grand Naine cultivars, revealed that both osmotic severity and varietal differences significantly influence the final product quality. Severe OD treatments, such as T8 (60°Brix, 24 h) and T12 (70°Brix + 1% salt, 24 h), effectively lowered moisture content (down to 38.94%) and increased Total Soluble Solids (TSS) and total sugars due to a maximized osmotic driving force and solute uptake, though this resulted in a reduced product yield. Crucially, the increase in reducing sugars and the subsequent decrease in non-reducing sugars over four months of storage confirm progressive sucrose inversion in the low-moisture matrix. Kamalapur Red consistently demonstrated a superior ability to retain Titratable Acidity (TA) and maintain higher TSS compared to Grand Naine, especially under rigorous treatments, indicating a distinct varietal response to mass transfer and product stabilization that is critical for selecting optimal processing parameters.

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