Chemical and microbial stability of high moisture dried apricots during storage

BACKGROUND: This study was conducted to determine the chemical and microbial stability of high moisture (HM) dried apricots during storage at 5, 20 and 30 °C for a period of 8 months. HM dried apricots were obtained by rehydrating dried apricots in ‘water’ and ‘water + H₂O₂’. RESULTS: Analysis of kinetic data suggested first‐order models for loss of SO₂ and non‐enzymatic browning reactions. Higher storage temperatures increased the rate of SO₂ loss and formation of brown colour in HM dried apricots. Results from extensive colour measurements (non‐enzymatic browning, reflectance colour and β‐carotene) revealed that the colour of HM dried apricots stored at 5 °C was almost unchanged during 8 months of storage. The colour of samples stored at 30 °C was unacceptable starting from 2 months of storage. Total mesophilic aerobic bacteria counts decreased 0.7, 1.1 and 1.5 log cycles after 8 months of storage at 5, 20 and 30 °C, respectively. For the same storage period, the decrease in mesophilic bacteria was 0.62 log cycle in samples rehydrated in ‘water + H₂O₂’ and stored at 20 °C. CONCLUSION: These results suggest that HM dried apricots should be stored at temperatures lower than 20 °C to preserve the characteristic golden yellow colour. A relatively low level of SO₂ (1458 mg kg^?1 at 200 g kg^?1 moisture level) was sufficient to prevent the growth of spoilage organisms in HM dried apricots at all three storage temperatures. Copyright © 2008 Society of Chemical Industry     

Changes in qualities of minimally processed litchis: Effect of antibrowning agents, osmo-vacuum drying and moderate vacuum packaging

Litchi fruits (litchis) are highly susceptible to pericarp browning which lowers their commercial value even though the edible portion (aril) remains in excellent condition. Therefore, minimal processing of litchis was carried out. Litchis were peeled, destoned, and arils were treated with antibrowning agents (4.9 g/kg cysteine, 20 g/kg ascorbic acid and 0.134 g/kg 4-hexyl resorcinol) along with osmo-vacuum dehydration (OVD) (502 g/kg sucrose syrup for 10 min at 570 mmHg vacuum followed by a relaxation of 10 min at atmospheric pressure) and stored at 4±2 °C. The samples were analyzed for physicochemical, sensory and microbiological qualities during storage. Changes were found to become significant (P?0.05) after 4 days of storage. During storage for 24 days, a decrease in pH, TSS (°brix), sugars (g/kg), ascorbic acid (g/kg), total phenolics (g/kg), firmness (N), color (L^* value) and sensory characteristics was observed whereas an increase in microbial counts (log cfu/g), acidity (g/kg) and drip losses (ml/kg) was observed. The combined treatment of litchis with antibrowning agents and osmo-vacuum dehydration treatment were found to be most effective in preventing the changes and the samples were acceptable (sensory score >7.0) upto 24 days, whereas the samples given only OVD treatment lost acceptability due to poor color after 16 days as compared to 8 days for the control samples (dipped in water for 10 min) during refrigerated storage.     

Changes in Chemical and Microbial Qualities of Dried Apricots Containing Sulphur Dioxide at Different Levels During Storage

Effects of different sulphur dioxide (SO₂) concentrations (188, 452, 791, 1,034, 1,236, 2,899 and 3,864 mg SO₂ kg^?1) and storage temperatures (5, 10, 20 and 30 °C) on the physical, chemical and microbial qualities of sulphited-dried apricots (SDAs) were evaluated. Analysis of kinetic data suggested first-order models for losses of moisture and SO₂ and formation of brown colour. Strong correlations were found between SO₂ concentrations and moisture loss constants (r?=??0.943), and brown colour values (r?=?0.949). β-carotene contents in SDA samples ranged from 26.6 to 36.2 mg 100 g^?1 dry weight, depending on SO₂ content of dried apricots. The SO₂ concentration over 791 mg per kg of dried apricots effectively protected carotenoids in dried apricots during drying. While storage times had significant effect on β-carotene contents, storage temperatures did not have such effects. The number of total mesophilic aerobic bacteria in all SDA samples ranged from 8.20?×?10¹ to 1.84?×?10² CFU g^?1. The number of total psychrophilic aerobic bacteria, lactic acid bacteria, yeast and mould, xerophilic mould, Staphylococcus spp. and total Enterobacteriaceae were below the detection limits (<4 CFU g^?1) in samples containing SO₂ even at the lowest level (188 mg SO₂ kg^–1) throughout the storage. Regardless of SO₂ concentration in dried apricots, low storage temperatures (below 20 °C) should be preferred to prevent the characteristic golden yellow colours of dried apricots.     

Effect of Calcium Lactate, 4-Hexyl Resorcinol and Vacuum Packing on Physico-chemical, Sensory and Microbiological Qualities of Minimally Processed Litchi (Litchi chinensis Sonn.)

Litchi (Litchi chinensis Sonn.) fruits are very susceptible to pericarp browning which adversely affects consumer acceptability even though the aril portion remains in excellent condition. Litchi arils (litchis) were treated with a solution containing 0–2% (w/v) calcium lactate (CL), 0–0.02% (w/v) 4‐hexyl resorcinol (4‐HR) and 1% potassium sorbate. The pH of solution was adjusted to 4.0 with citric acid. Treated litchis were packed in polystyrene trays, over‐wrapped with polypropylene film, vacuum‐packed (0, 47409.3, 94831.9 Pa) and stored at 4 ± 2 °C. Drip losses, pH, total soluble solids (TSS), sensory attributes and microbiological quality of stored samples were estimated. A four‐factor, three‐level experimental design (D₆ Hokes design) with 19 experiments was chosen. Mathematical models were developed to analyse and predict the effect of CL, 4‐HR, in‐package vacuum and storage time on the responses. TSS, pH and sensory scores decreased significantly (P 0.01), whereas drip losses and microbial count increased significantly (P 0.01) with time. Drip loss was significantly (P 0.1) reduced by addition of CL. 4‐HR prevented browning and changes in colour score during storage were significantly less. Vacuum in packages exerted significant (P 0.01) effect over pH, TSS, sensory and microbiological qualities of minimally processed litchis.     

The glass transition approach to determination of drying protocols for colour stability in dehydrated pear slices

Colour stability in dehydrated fruit is often attained by use of sulphite treatment to inhibit browning during processing and storage. However, colour stability may be able to be conferred on products by ensuring that the molecular mobility is restricted in dried fruit by drying to sufficiently low moisture to raise the glass transition temperature (under mild conditions). Pear slices were dehydrated at a low temperature (40 °C) to a low final moisture content (below 5%) after it was shown that, for a moisture content of 22% (which is the moisture content of commercial dehydrated pears) pretreatment with sulphite would be necessary to stabilise the colour. The use of longer drying regimes resulted in a moisture content where the food matrix would be closer to the glassy state and conferred colour stability on the dehydrated product compared to a product containing more moisture. For these low‐moisture products, pretreatment with sulphite would not be necessary to preserve colour stability.     

Effects of pretreatments on the quality of open-air and solar dried apricots

Apricots, pretreated with SO₂ gas, sodium-meta-bisulfite or SO₂ gas/ ethyl oleate, were open-air or solar dried. Increasing initial SO₂ concentrations, ranging from 3600 to 10100 mg/kg dry matter, increased the drying rates depending on the type of the pretreatment and the drying method. In the range 47–74% of the initially available SO₂ is lost during drying. Hunter L (lightness) and +b (yellowness) values of SO₂ gas treated-dried apricots were slightly larger than those of others. Ethyl oleate treatment, in addition to SO₂ gas, accelerated both the drying and browning rates (decreasing Hunter L value). In general, Hunter +a (redness) increased upon drying of apricots.     

Browning reactions during storage of low-moisture Australian sultanas: Further evidence for arginine-mediated Maillard reactions during storage, and some effects of vine-shading and harvest date

Sultana grapevines (Vitis Vinifera L. cv. Sultana syn. Thompson Seedless) were subjected to four shading regimes: 50% shading (1), 25% shading (2), fully exposed‐top of canopy (3) and beneath canopy (4) and harvested early (21 February) and late (13 March) in the 1996/1997 sultana season. Grapes from each of the eight field‐treatment combinations represented a range of maturities (14.4 to 23.50^oBrix). Grape samples from each of the treatments were dipped and dried to 18% moisture, with half of each of the sultana samples further reduced in moisture by sunfinishing on plastic sheets in direct sun. These field treatments resulted in sixteen unique dried sultana bulk samples with a range of initial chemico‐physical properties; a_w (0.481–0.691), skin‐polyphenoloxidase (PPO) activity (4.40–9.05 μmol O₂/g.minute) free arginine in skin tissues (1.0–5.10 mg/g) and protein (16.40–27.18 mg/g). Sultanas were stored at 10^oC and 30^oC in either the presence or absence of oxygen for 10 months, and changes in CIE L*a*b* tristimulus values, hue‐angle (h_ab*) and chroma (C_ab*) were monitored. Significant changes in sultana colour occurred in samples stored at 30^oC, especially in higher a_w non‐sunfinished sultanas. Although browning was more intense in the presence of oxygen, significant browning also occurred in the absence of oxygen. Lower concentrations of 5‐hydroxy methylfurfural, a key marker of Maillard browning in samples stored at 30^oC in the presence of oxygen, indicated that the non‐enzymatic reactions were sensitive to oxygen. Changes in the concentration of trans‐caftaric acid, the main substrate of grape PPO, were also measured during sultana drying. Storage browning (changes in L*, b*, h_ab*, C_ab*)in dried sultanas could be predicted by regression models using pre‐storage a_w, free‐skin arginine or Kjeldahl protein after 10 months' storage between 10^oC and 30^oC. Non‐enzymatic and Maillard‐type reactions (sensitive to both oxygen and a_w), made an important contribution to sultana storage browning. We provide only weak evidence that either shaded (immature) or green fruit was more susceptible to storage browning.     

Fruit quality and physiological responses of litchi cultivar McLean's Red to 1-methylcyclopropene pre-treatment and controlled atmosphere storage conditions

The effect of 1-MCP pre-treatment and two different controlled atmosphere storage conditions (CA-1, 17% O₂ + 6% CO₂; CA-2, 7% O₂ + 3% CO₂) on fruit quality parameters and physiological changes with respect to pericarp browning in ‘McLean's Red’ litchi were investigated. Fruits were pre-treated with 1-MCP (500 nl/l) and held at CA-1 or CA-2 for 21 d at 2 °C and at 90% RH. Stand-alone CA-1 or stand-alone CA-2 and the commercially adopted sulphur dioxide (SO₂) treatment were included in this study for comparison. Of the five treatments 1-MCP + CA-1 was most effective in preventing browning, loss of red colour (colour value a*) of the pericarp, ascorbic acid content; and retaining acceptable SSC/TA and taste. Fruit from 1-MCP + CA-1 showed higher overall acceptance after 21 d storage without any off-flavour according to the sensory panel data.1-MCP + CA-1 reduced the polyphenol oxidase (PPO) and peroxidase (POD) activity, retained membrane integrity and anthocyanin content during storage. Although SO₂ treatment prevents browning it showed negative effects on SSC/TA, taste and membrane integrity. Stand-alone CA-2 condition indicated higher pericarp browning, PPO, POD activity and loss of membrane integrity. Therefore, 1-MCP pre-treatment and CA-1 retains overall fruit quality for up to 21 d.     

Air Drying Characteristics of Apricots

The optimization of the drying of apricots was studied using four treatments: (1) blanching and drying; (2) sulfiting-blanching and drying; (3) blanching-sulfiting and drying; and (4) sulfiting-drying to 50% moisture-blanching and finish drying. Levels of sulfiting were from 0–2000 ppm SO₂ and drying was done at 50° to 80°C. The quality of dried apricots was judged by extent of browning development and hardness determination. A surface response statistical design was applied to evaluate the optimum drying conditions. Sulfiting-drying, using 80–1000 ppm SO₂ at any temperature in the range 50–80°C, was found to be the best treatment. Thus, sulfite was the major factor in controlling dry apricot quality and would be hard to reduce. Drying time was reduced by 50% when apricots were dried at 80°C compared to 50°C, and blanching reduced the time by 10 to 20%. Loss of SO₂ was greater than 50% for all treatments.     

Quality improvement of non-sulphited mango slices by drying at high temperatures

An optimum drying routine for producing non-sulphited mango slices has been developed. The interaction of essential drying parameters (air temperature, air velocity, dew point, slice thickness and drying time) on water activity (a_W) and browning was determined. Microbiological stability of the dried product was achieved at a moisture content of 17% wet base (w.b.) corresponding to a_W = 0.6. Browning was monitored by the red colour shade of the product (CIE-Lab chromaticity coordinate a*). Drying air temperature and drying time were shown to be the primary factors influencing product colour and a_W. In contrast to common practice, drying for about 6 h at elevated air temperature (80 °C), instead of 50 or 60 °C for a longer time, was optimal, since significant colour changes of the mango slices were not observed even without the use of any chemical or thermal pre-treatment. Moreover, at increased temperature, drying time was considerably shortened from about 9 h to 6 h, resulting in significant extension of the drying capacity.

Industrial Relevance

The suggested process concept for dried mango slices based on high-temperature drying is of utmost significance for the international marketing of dried fruit products. Chemical pre-treatments such as sulphitation often used to minimise quality deficiencies could be avoided. Sulphitation has been recently under critical consideration with respect to allergen labelling of foodstuffs implemented by EU-Member States in November 2004 (Directive 2003/89/EC) [Directive 2003/89/EC. Official Journal of the European Union, 25.11.2003, pp. L308/15–18 (http://europa.eu.int/eur-lex/pri/en/oj/dat/2003/l_308/l_30820031125en00150018.pdf)]. Export quality was improved and the drying process simplified, improving the utilisation of drying capacities. Particularly referring to an application of the technology in small- and medium-sized enterprises with limited investment possibilities, the suggested novel drying procedure in mango processing aimed at the optimisation of well-established simple drying methods instead of choosing technically more sophisticated technologies.     

Storage Conditions Affect Quality of Raisins

Raisins had a moisture content of ca 14% and were stored over an 11 mo period. The initial SO₂ content was ca 640 ppm. Moisture content, water activity, color, browning, texture, SO₂ content, soluble sugars, acidity and pH were periodically determined. A substantial decrease in SO₂ content was observed, especially in samples stored at room temperature (20–25°C) which had higher browning indexes. No substantial changes were detected in water activity, acidity and pH. No sugaring was observed. Refrigerated samples (stored at 4 and 11°C) were of higher quality in comparison with nonrefrigerated samples. Both were suitable for consumption after storage.     

Browning reactions during storage of low-moisture Australian sultanas: Evidence for arginine-mediated Maillard reactions

Browning during storage of low‐moisture dried Vitis Vinifera L. cv. Sultana (Thompson Seedless) grapes was examined in a multifactorial treatment and storage trial. Grapevines were subjected to two different levels of sun exposure, harvested fruit was dipped and subjected to different drying treatments to obtain a range of initial moisture contents (a_w= 0.419–0.558). The storage effects of temperature (10^oC and 30^oC), and the presence of oxygen on colour change (CIE L*a*b* tristimulus values, hue‐angle (h_ab*)) and chroma (C_ab*) over a fourteen‐month period were observed. The most significant changes in colour were measured for samples stored at 30^oC, both aerobically and anaerobically, although the largest changes occurred in the presence of oxygen. Initial a_w had a strong effect on colour changes; higher a_w non‐sunfinished samples underwent more significant browning compared to lower a_w sunfinished controls regardless of their oxygen status. Changes in the concentration of the free‐arginine and free‐proline, the most abundant free amino acids in sultanas, were monitored throughout the storage period. Free arginine decreased significantly at 30^oC in both the absence and presence of oxygen, whereas free proline increased (at both 10^oC and 30^oC), implying that free proline did not play a role in browning reactions at those temperatures. In addition to the decreases in free arginine, the concentration of 5‐hydroxymethyl furfural (5‐HMF), a marker of Maillard browning reactions, increased significantly in samples stored at 30^oC. Significant differences in the concentrations of 5‐HMF under the two oxygen conditions indicated sultana Maillard reactions, and possibly other non‐enzymatic browning processes, were oxygen sensitive.     

Effects of different pre-freezing blanching procedures on the physicochemical properties of Brassica rapa leaves (Turnip Greens, Grelos)

For optimal freeze storage, green vegetables should first be blanched. The present study compared four different procedures for the blanching of grelos (leaves of Brassica rapa L.): steaming for 2 min, immersion in boiling water for 2 min, immersion in boiling water containing 1% citric acid for 1 min, and immersion in boiling water containing 5% citric acid for 1 min. After blanching, the grelos were stored for up to 120 days at ?18 °C, with sampling at two‐weekly intervals for analysis of physicochemical properties (ash weight, vitamin C content, pH, acid value, moisture content and CIE_L*a*b* colour variables). In almost all respects steam blanching gave the best results: notably, vitamin C losses were markedly lower, while moisture content and colour remained closer to those of the fresh product.     

Optimisation of vacuum frying of gold kiwifruit slices: application of response surface methodology

Response surface methodology was used to investigate the effects of the level of maltodextrin (MD), frying temperature and time on the moisture, colour and texture properties of the vacuum‐fried gold kiwifruit slices and to determine the optimised conditions for vacuum frying. The moisture content of vacuum‐fried gold kiwifruit slices decreased with increasing frying temperature and frying time. The colour change of the product increased with increasing frying temperature. The browning index of the product increased with increasing frying temperature and frying time. The breaking force of the product gave higher values when processed at middle range of frying temperature and MD level. When processing vacuum‐fried gold kiwifruit slices, there was a need to use frying temperatures of 72.0–76.3 °C, frying times of 35.0–65.0 min and an MD level of 40% to achieve products with acceptable moisture, colour and texture properties.     

Fruit snacks from raspberries: influence of drying parameters on colour degradation and bioactive potential

Raspberries were dehydrated using air and freeze‐drying with wet and dry sugar infusion pretreatments. Product quality factors such as colour, bioactive compounds, antioxidant capacity and sensorial characteristics were analysed. Special emphasis was placed on the analysis of anthocyanin degradation and its relationship with colour deterioration and with polymeric compounds development and browning. Freeze‐dried raspberries presented a higher retention of bioactive compounds and a lower content of polymeric compounds than air‐dried ones. Dried samples without pretreatment (control) showed the highest retention of total phenolic content (freeze‐dried ≈82% and air‐dried ≈37% retention), but the lowest sensory acceptability. Although sugar infusion pretreatments caused an important loss of bioactive compounds (9–18% of TPC retention), a higher sensorial acceptability was obtained. Pretreatments with bisulphite and acid allowed obtaining the best quality attributes in terms of anthocyanin and polyphenol content, antiradical activity and colour retention. Polyphenol intake through pretreated dried raspberries (115–299 mg gallic ac./100 g intake) would be higher in some cases than that of usually consumed foods as vegetables, cereals and several fresh fruits.     

Optimization of processing of fresh‐cut pear

BACKGROUND: Successful processing of pears to render fresh‐cut fruits requires a thorough knowledge of their sensitivity to browning reactions, their respiratory metabolism, and their behaviour under modified atmosphere packaging. RESULTS: First, three different varieties of pear (Williams, Conference, Passacrassana) that had reached their commercial ripening stage were evaluated for suitability for minimal processing. Two antioxidant treatments were tested (treatment 1: 2% ascorbic acid + 1% citric acid + 1% CaCl₂; treatment 2: 2% ascorbic acid + 0.01% 4‐hexylresorcinol + 1% CaCl₂) to decide which one was the most effective against enzymatic browning. Finally, a modified atmosphere packaging was designed after two previous tests: measurement of respiratory activity of the peeled and cut pear at three temperatures (4, 15 and 25 °C); and evaluation of fruit tolerance to three different atmospheric compositions (21% O₂ + 10% CO₂; 2% O₂ + 0% CO₂; 2% O₂ + 10% CO₂). CONCLUSIONS: Conference pear was found to be the most suitable variety. Among the antioxidant treatments the one consisting of ascorbic acid, 4‐hexylresorcinol and CaCl₂ was proven to be the most effective against browning. The samples were packaged in a modified atmosphere with a composition of 10% O₂ + 10% CO₂ + 80% N₂. Copyright © 2008 Society of Chemical Industry     

Catalytic Infrared Dehydration of Onions

ABSTRACT:  Dehydrated onions are commonly dried with convection heating, which is inefficient and costly. This study compared the drying and quality characteristics of onion dried with catalytic infrared (CIR) heating and forced air convection (FAC) heating. Sliced high-solids onions were dehydrated under 9 conditions: CIR heating with and without air recirculation, and FAC each operated at 60, 70, and 80 °C. In general, CIR both with and without air recirculation had higher maximum drying rates, shorter drying times, and greater drying constants than FAC at moisture contents greater than 50% (d.b.). Dried onion quality, measured as pungency degradation, was similar for both the drying methods at 60 and 70 °C. The color analysis showed better product color (whiter and less yellow) at lower temperatures for CIR and higher temperatures for FAC. The browning could have been caused by the higher surface heat flux of the CIR heating and longer process times of FAC drying. Aerobic plate counts and coliform counts were not significantly different for either product from the CIR or FAC drying. However, samples dried by the CIR had significantly lower yeast and mold counts than those dried by the FAC. It is recommended that CIR be used in the early stages of onion drying.     

Effect of Carbonic Maceration Pre-treatment on Drying Kinetics of Chilli (Capsicum annuum L.) Flesh and Quality of Dried Product

A new pre-treatment — carbonic maceration (CM) pre-treatment — was presented in this paper. To study the effect of CM on microwave drying (MD) kinetics of Chilli flesh and quality of dried product, the fresh (control group, CK) and CM pre-treated samples were dried through MD at 100, 150 and 200 W, respectively. CM conditions were optimized by orthogonal test. The drying results indicated that, the average drying rate for CM samples were as much as 150–185 % of these for CK samples. For both CK and CM samples, the drying rate increased at the initial time (a warming-up period) and then decreased at the end time (a falling rate period) after reaching a plateau (a constant rate period). And the effective diffusivity, D _eff, increased gradually at the initial period and then rapidly at the final period with the diminishing moisture content. Elevated microwave power levels could lead to a linear increase in values of D _eff at the same moisture content. The activation energy, E _a, increased rapidly when moisture content was below about 1 g water/g dry mass, which was lower for CM samples than for CK samples, and can be well described with a logistic model. Scavenging free radical capability (DPPH), ferric reducing antioxidant power (FRAP), total phenol contents and vitamin C retention contents of the dried products for CM samples were as much as 170.1–190.9 %, 140.2–147.8 %, 140.1–160.0 % and 212.7–682.4 % of these for CK samples, respectively. The CM dried products were also better in terms of colour differences than CK.     

ning reactions during storage of low-moisture Australian sultanas: Effects of vine nitrogen nutrition on subsequent arginine-mediated Maillard reactions during storage of dried fruit

Ten‐year old Vitis Vinifera L. cv. Sultana (Thompson Seedless) grape vines were transferred into large cement pots in low nitrate soil and supplemented with four levels of nitrogen application in the form of ammonium nitrate as follows: 0 g ( N₀ ), 8.5 g ( N₁ ), 17.0 g ( N₂ ) and 25.0 g ( N₃ ). Grapes were harvested from each nitrogen treatment, dipped and dried to low moisture (?11.4%) and subsequently stored for 10 months at 10^oC and at 30^oC in either the presence or absence of oxygen. The pre‐storage concentration of free arginine, free‐proline and total protein in the dried sultanas increased with soil nitrogen application. Skin‐polyphenoloxidase (PPO) activity was higher in sultanas with added soil nitrogen ( N₁, N₂, N₃ ), however pre‐storage differences in total phenolics, and the PPO substrate, trans‐caftaric acid, were not significantly different. After 10 months storage at 30^oC significant browning was observed in both the presence and absence of oxygen. Greater browning corresponded to higher soil‐nitrogen application rates. The concentration of skin trans‐caftaric acid did not decrease in N₀, N₁ or N₂ after 10 months at 30^oC, in either the presence or absence of oxygen, although some decreases were measured in the highest nitrogen sultanas ( N₃ ). While PPO oxidation of the phenolic substrate trans‐caftaric acid was not the primary route to browning, a number of Maillard reaction products (MRP) were present in both sultanas and arginine‐glucose model systems. Those products were separated via reverse phase HPLC and partially characterised by UV‐diode array spectroscopy. The lack of oxidation of trans‐caftaric acid observed in the nitrogen storage trial was confirmed in an accelerated browning experiment in low‐moisture sultanas, where despite browning at 50^oC after 12 days, no decreases in this primary substrate for PPO‐mediated oxidation were measured.     

Effects of osmo-dehydration,blanching and semi-ripening on the viscoelastic,water activity and colorimetry properties of flour from three cultivars of plantain (Musa AAB)

The viscoelastic properties, water activity and colorimetry measurements of plantain flour produced by hot-air dehydration of three cultivars, French Horn, False Horn and True Horn local plantains were studied. Treatments given to the plantains before the hot-air dehydration were osmo-dehydration, hot-water blanching and semi-ripening and fresh unripe. The best pasting characteristics occurred for True Horn local and False Horn osmo-dehydrated flours. Water activity and moisture content were 0.27–0.39 a_w and 5.08–7.25%, respectively with the lowest recorded for False Horn osmo-dehydrated flour. Colour parameters were in the range of 87.34–79.56 and 15.71–26.74 for L? and b?, respectively. The least browning colour (a?) was exhibited by True Horn local and False Horn osmo-dehydrated flours. Statistical significances (P < 0.05) were recorded for water activity, moisture content and a? colour parameter between process treatments for fresh unripe, semi-ripe, osmo-dehydration and blanching whereas no statistically significances occurred for varietal differences for False Horn, True Horn local and French Horn plantains. However, the viscoelastic properties were significant for F-ratios at P > 0.05. Process treatments of osmo-dehydration, blanching and semi-ripening contribute significantly to the differences for water activity, moisture content, browning effect and viscoelastic properties compared to plantain varieties, with osmo-dehydration emerging as the best treatment method.Industrial relevanceThis work is a representation of peculiar differences for water activity, moisture content, non-enzymatic browning effect and viscoelastic properties among process treatments of osmo-dehydration, blanching, semi-ripening and fresh unripe. Important results were obtained for the flour industries for decisions on selecting osmo-dehydration among the process treatments for plantain (Musa AAB) flour in order to take advantage of the consumer demand for plantain flour.