Mandarin Cv Research Articles

Bioactive Phytochemical Contents on Fruit Peel of Several Citrus Species

Citrus fruits contain important sources of bioactive compounds, including antioxidants such as flavonoids and phenolic compounds that are beneficial for human health. These bioactive compounds also exist in non-edible fruit parts, like the peel. The research was conducted to evaluate these bioactive phytochemicals on the peels of different citrus species. The experiment was carried out from March to August 2018 at the citrus germplasm collection of the Indonesian Instrument Standard Assessment Institute for Citrus and Subtropical Fruits and The Central Laboratory of The Indonesian Instrument Standard Assessment Institute for Legumes and Tubers Crops. The steps of research methods included the preparation of extract samples, the determination of total flavonoids and phenol content, and the DPPH radical scavenging assay. The results showed that the bioactive content of the citrus peels of several citrus species was diverse among the studied citrus species. Tangerine citrus cv. Kintamani was observed to have a higher phenolic content. For flavonoid content, the peel of lime cv. Borneo had the highest and Mandarin cv. Satsuma showed the least. Higher DPPH radical-scavenging activity values were observed on Mandarin cv. Pachuan, tangerine cv. Kintamani, and pumello cv. Thn. The correlation between phenolic content and DPPH radical-scavenging activity was higher than that between phenolic-flavonoid and flavonoid-DPPH radical-scavenging activity, indicating the effect of active molecule structure on redox potential.

Manipulation of flowering and fruiting induction through branch bending and fertilizer application in mandarin citrus cv. Batu 55

Shoot modification for triggering flowering and fruiting induction in tropical mandarin citrus is not extensively documented, hence this research is critically important. The purpose of this study was to determine the influence of branch bending and fertilizer application on flowering and fruiting, hormonal level status, and physiological features in mandarin citrus cv. Batu 55. From May 2021 to March 2022, the investigation was carried out at Farmer‘s citrus orchard Dau in Malang (1,300 m above sea level), East Java, Indonesia. Bending (B1) or unbending (B0) and fertilizer (F1) or no fertilizer (F0) treatments were performed on existing three-year-old Mandarin cv Batu 55 trees with a planting distance of 3 x 3 m. The experiment was set up in a factorial randomized block design with four interaction treatments (B0F0, B0F1, B1F0, B1F1) and three replications. When compared to the control, the bending treatment with fertilizer application treatment raised the percentage of flowering plants by 100%. Five and nine months after treatments, the amount of fruit produced and harvested by this treatment was more than 19 and 1.6 times that of control plants, respectively. Branch bending and unbending treatments had relatively similar effects on the endogenous hormonal status and physiological behavior. Branch bending at the appropriate time of year may be beneficial in stimulating flowering and fruiting in mandarin cv Batu 55.

Effect of bud position on the seedling growth of five citrus species

This research aimed to evaluate the bud position in the vegetative phase of seedling growth derived from five citrus species. The research was carried out from April to July 2018 at the Tlekung Agricultural Research Installation. Factorial Randomized Block Design with two factors is the method in this study. The bud position taken as the propagation material was the first factor consisting of the top (36-50 cm from the base part of tree), middle (16-35 cm from the base part of tree), and bottom (0-15 cm from the base part of tree). The second factor was the citrus species consisting of mandarin cv. Madura, tangerine cv. Pontianak, pummelo cv. Giri Matang, lime cv. Sweet, and orange cv. Punten. There was no significant interaction between the bud position and species on all variables. However, regardless of bud position, citrus species showed significantly different in vegetative growth. The best average of 100% for the success of bud grafting, 36.89 days after bud grafting for the budburst time, 4.5 mm for the shoot diameter, 29.81 cm for the shoot length, and 19.55 leaves for the number of leaves was shown by orange cv. Punten. The results of this research sugges that the use of buds taken from different positions is recommended for citrus grafted bud.

Mapping of QTLs for citrus quality traits throughout the fruit maturation process on clementine (Citrus reticulata × C. sinensis) and mandarin (C. reticulata Blanco) genetic maps

Citrus fruit quality is defined as the combination of physical and chemical traits; some of which may change during the ripening phase, e.g., acidity and sugar content. A clear understanding of their genetic control would be very helpful for marker-assisted breeding programs especially with regard to the juvenile phase and some reproductive features that hamper the selection of improved hybrids. A genetic study was thus performed on the heredity of quality traits and QTL detection based on segregation in a progeny generated from a cross between clementine cv “Commun” (Citrus × reticulata cv clementine) and mandarin cv “Willow leaf” (C. reticulata Blanco). Parental and consensus genetic linkage maps were constructed using 645 SNP and SSR markers. These maps were represented by 10 linkage groups in clementine and 12 linkage groups in mandarin, representing 75% and 58% respectively of the previously published clementine reference map. A total of 16 traits, including fruit mass, equatorial diameter, juice percentage, total soluble solids, acidity, pH, glucose, fructose, sucrose, and citric and malic acid concentrations were evaluated at three maturation dates. High variations indicating transgressive segregation were found for all traits, with normal or close to normal distributions. QTL analysis performed using the multiple QTL model allowed the detection of 34 QTLs on the three maps. QTLs were distributed in different linkage groups and generally detected at only one date of the ripening phase. The percentage of total variation explained ranged from 12 to 37% per QTL. Major QTLs (R2 ≥ 30%) were detected for equatorial diameter, glucose, and fructose (expressed in percentage dry matter) on linkage groups 8 and 9. Co-localization of QTLs controlling correlated and uncorrelated traits were mainly found on linkage groups 2, 4, 8, and 9, particularly between fruit mass and acidity.

Response of Potted Citrus Trees Subjected to Water Deficit Irrigation with the Application of Superabsorbent Polyacrylamide Polymers

Searching for new strategies to mitigate the effects of low water availability for citrus production, a study was carried out on potted mandarin cv. W. Murcott, with the objective of evaluating the physiological and growth response of the plants to polyacrylamide gel application in the substrate in water restriction conditions. The following treatments were evaluated, T0 (control) with 100% ETc water replenishment, T1 with 50% ETc water replenishment, and T2 with 50% ETc water replenishment plus the application of polyacrylamide polymers to the substrate. Temperature and water volumetric content (ϴ: m3 m−3) were evaluated in the substrate. Plant water-status parameters such as stem water potential (SWP), stomatal conductance (gs), and chlorophyll fluorescence (Fv/Fm), as well as biomass, nutrients levels, and proline biosynthesis were measured in the plants in response to the treatments. The results showed that the substrate moisture for T2 was kept significantly higher than T0 and T1, despite receiving the same irrigation rate as T1 and a half of T0; however, this higher moisture availability in the substrate of T2 was not reflected in the plant’s water status or growth. On the contrary, the T2 plants showed responses such as lower total biomass, lower vegetative development, and lower root biomass, as well as a higher concentration of proline in the root. According to these results, it is concluded that polymers such as polyacrylamide sodium allow the retention of water in the substrate, but do not necessarily release that water for plants, probably because that moisture is kept in the hydrogel and not released to the substrate media or the roots, or if released, in this case, this occurs with an increase in the concentration of sodium available to the plants, which could lead the citrus crop to a worse situation of water and/or osmotic stress.

Field Inoculation of Arbuscular Mycorrhizal Fungi Improves Fruit Quality and Root Physiological Activity of Citrus

Soil arbuscular mycorrhizal (AM) fungi form a mutualistic symbiosis with plant roots and produce many benefits on host plants under potted conditions, while field inoculation of AM fungi on citrus (a woody plant) has been rarely reported. The present study aimed to analyze the changes in mycorrhizal growth, root vitality, and fruit quality of Citrus reticulata Blanco var. Ponkan mandarin cv. Jinshuigan grafted on Poncirus trifoliata L. after inoculation with a mix of AM fungi (Diversispora versiformis, Funneliformis mosseae, and Rhizophagus intraradices) and single F. mosseae. After the second year of AM fungal inoculations, root mycorrhizal colonization (%), root vitality, hyphal length in soil, and easily extractable glomalin-related soil protein content were significantly increased, while difficult-to-extract glomalin-related soil protein content was decreased. Two mycorrhizal fungal inoculation treatments collectively improved fruit quality parameters such as polar diameter, equatorial diameter, the weight of single fruits, fruit peel, and sarcocarp, coloration value, and soluble solids content. Our study, therefore, suggested that field inoculation with AM fungi improved root physiological activities in terms of mycorrhizal growth and root vitality and thus improved fruit quality. The effect of mixed-AM treatment was more significant than that of F. mosseae alone.

Evaluation of the certified citrus commercial seedlings distribution program for citrus fruit supply stability

Nurseries belong to the upstream hierarchy in the production chain hence, play an integral role in sustainable food production. The Indonesian Citrus and Subtropical Fruits Research Institute (ICSFRI) between 2018 and 2020, distributed 296,297 certified citrus commercial seedlings for East and Central Java provinces. Meanwhile, an evaluation of the program showed that it is applicable as a reference to improve and forecast stability in citrus fruit supply. This study was conducted using descriptive and inferential statistics, meanwhile, a total of twenty citrus varieties were distributed. The main variety distributed in East and Central Java were tangerine cv Pontianak and mandarin cv Batu55 respectively, while three regencies in East Java and two in Central Java were sampled as the study locations, thereafter, a total of 73 beneficiary farmers were selected as respondents. The result showed that the death rate for distributed seedlings was relatively low, with the tangerine cv Pontianak indicating the highest death compared to mandarin cv Madura. This implies that the supply of tangerine and mandarin is expected to increase approximately by three thousand tons within the next two to three years. Besides this amount is predicted to consitute 3% of import in 2019. However, to actualize this, improvement in water availability, weather forecast, as well as farmer empowerment need to be considered to meet up with citrus supply, both in quantity and quality.

Analysis of consumer preferences for 5 varieties of mandarins

The development of commercial citrus varieties must be in line with consumer preferences. The purpose of this study was to identify the consumer preferences for 5 varieties of mandarins, namely Batu 55, Monita Agrihorti, Terigas, Madura, and Garut. The study was conducted at Indonesian Citrus and Subtropical Fruits Research Institute (ICSFRI) by performing an affective test. The sensory attributes assessed were fruit cleanliness, fruit shape, fruit skin color, ease of peeling, fruit flesh color, fruit flavor, and number of seeds. The results showed that for Mandarin cv. Batu 55, Monita Agrihorti and Madura, consumers liked all the sensory attributes of those varieties including fruit cleanliness, fruit shape, fruit skin color, ease of peeling, fruit flesh color, fruit flavor, and number of seeds. For Mandarin cv. Terigas, consumers liked the fruit shape and fruit flesh color. For Mandarin cv. Garut, consumers liked the attributes of fruit cleanliness, fruit shape, ease of peeling, fruit flesh color and number of seeds. The attributes of fruit shape and fruit flesh color at all types of mandarins were preferred by consumers. While the attributes of fruit cleanliness, skin color, ease of peeling, fruit taste, and number of seeds at several types of mandarins were still less favored by consumers. Thus, improving the lacking quality of the mandarins needs to be done.

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Effect of storage conditions, preservative levels and packing materials on ascorbic acid juice of mandarin cv. Nagpur Santra

The research was done with the aim of considering vitamin C affectability under different storage conditions and packages at the post-harvest center of Mpkv, Rahuri Agricultural University in India. Juice of Nagpur Santra in three packaging materials glass bottles of 200 mL (B1), pet bottles of 200 mL (B2) and standy pouches (B3) which were added sodium benzoate as preservative substance in three levels 150 ppm (P1), 250 ppm (P2) and 350 ppm (P3), were kept in roam temperature range 19 to 28°C (S1) and cold storage 5±2°C (S2) were used for vitamin C consideration at days 30, 60, 90, 120, 150 and 180 of storage period. Results showed that ascorbic acid of Nagpur Santra juice was significantly influenced by storage conditions, preservative levels, packaging materials and their -1 interactions. The ascorbic acid (AA) of fresh juice was 43.46 mg 100 mL . During storage AA was found to be decreased in all the treatment combinations. However, the rate was faster under ambient condition (S1) as compared to cold storage (S2) condition. The minimum decrease in AA of juice was found in high preservative level when packed in glass bottle and stored in cold storage. The maximum AA was recorded in S2P3B1 (35.21 mg 100 mL-1) followed by S2P3B2 (34.23 mg 100 mL-1) at 180 days of storage. The minimum AA was recorded in S1P1B3 (23.69 mg 100 mL-1) followed by S1P1B2 (24.60 mg 100 mL-1) at 90 days of storage period and afterward it spoiled. It can be said due to high quantity of AA in Nagpur Santra even after long period of storage time the level of AA of mentioned fruit juice was at acceptable level from view point of nutritional value.

Inducing mutations in Citrus spp.: Sensitivity of different sources of plant material to gamma radiation

Gamma radiation represents an alternative for improving genotypes for which breeding through hybridization involves many difficulties because of their complex reproductive biology, as in the case of citrus. In this study in vitro and ex vitro mutagenesis was induced by gamma radiation in several citrus species (‘Alemow’ and sour orange as citrus rootstocks, lemon cv. ‘Fino 49’ and ‘Verna 51’, mandarin cv. ‘Nova’ and lime cv. ‘Bearss’). Three different sources of materials - seeds, budwoods and nodal segments - from in vitro explants, were tested. Seeds and budwoods were germinated or induced to sprout, and de novo regeneration was obtained from in vitro nodal segments from which preexisting buds were previously removed. Budwoods were tested in summer and winter in order to assess their capacity for mutation and further sprouted in different seasons. Seeds were seen to be more resistant to gamma radiation (LD50 of 127 Gy in ‘Alemow and 156 Gy in sour orange) than budwoods (LD50 about 50 Gy for all cultivars) and nodal segments (LD50 about 25 Gy for both lemon cultivars), the last being the most sensitive material tested. Similar LD50 were found for budwoods collected in winter and summer for all the genotypes. All the tested plant material can be considered suitable for gamma irradiation, although budwood is the most widely available and tissue culture material needs the highest degree of expertise.

Pre- and postharvest application of alternative means to control Alternaria Brown spot of citrus

Alternaria brown spot (ABS) is one of the main diseases of mandarins and their hybrids. Its control is based on fungicide applications, but their use is facing difficulties related to the development of resistant pathogen strains and adverse effects on animals, humans and the environment. The present study was undertaken to find feasible alternative solutions to control ABS, by testing the effectiveness of phenolic compounds and alternative formulations present on the market. They were tested in vitro and in vivo on a laboratory scale and then in semi-commercial conditions. Umbelliferone was the most effective phenolic compound in controlling by 86% ABS on mandarins cv. Fortune in semi-commercial conditions. Its effect seemed related to the ability of inducing resistance in the host. Whereas among the formulations, chitosan-based HendophytPS and salt-based FortisolCaPlus gave the best results in field-scale trials, with a reduction of disease incidence by 59–63 and 54–75% on fruit and leaves, respectively, as compared to the control, being the effect similar to that obtained by chemical controls. The formulations showed mainly to induce host resistance. The application of proposed alternative treatments, singly or in a combined strategy, might represent an interesting substitute to synthetic fungicides against ABS.

Citrus gummosis incidence and role of ants (Lasius grandis) and snails (Helix aspersa) as vectors of the disease in Tunisia

SummarySurveys were conducted between November 2011 and December 2013 to determine the distribution and the incidence of citrus gummosis in Tunisia. Forty‐two citrus orchards in three different citrus areas were surveyed. Symptoms of gummosis were observed in 59.52% of the orchards. The highest incidence was observed in the Cap Bon area. The involvement of some invertebrates in the epidemiology of citrus gummosis was also confirmed. Species of ants (Lasius grandis), snails (Helix aspersa and Rumina decollata) and worms (Armadillidium vulgare) collected from 2012 until 2014 were tested for the presence of Oomycetes. Phytophthora nicotianae and Phytopythium vexans were isolated from the bodies of Lasius grandis and also from bodies and faeces of Helix aspersa. However, no Oomycetes were isolated from the bodies of Rumina decollata and Armadillidium vulgare. In vitro assays, Helix aspersa was fed with P. nicotianae‐ and Ph. vexans‐infected citrus bark showed the existence of those pathogens in 79.1% of the faeces of snails. In vivo assays, snails and ants were able to transmit the pathogens vertically from the base of potted 2‐year‐old trees citrus variety Clementine Mandarin cv. Hernandina, to other parts of the tree.

Pitch height as part of speech plans: Evidence from response to auditory startle

In Mandarin, pitch contour denotes phonemic contrast while pitch height does not serve as a phonemic parameter. When triggered by a startling auditory stimulus (SAS, >120dB), prepared Mandarin CV syllable [ba] is elicited rapidly while its pitch contour remains unperturbed, suggesting that phonemic details are included in the speech plan and susceptible for rapid release under feedforward control [Chiu and Gick 2014, JASA-EL, 322-328]. Pitch height, however, is elevated in SAS-induced responses. It is not clear whether or not pitch height can be independently pre-specified in speech plans. The current study uses the startle paradigm to tackle this question by comparing general Mandarin speakers and Mandarin speakers with pitch training. Preliminary results show that specific pitch height can be prepared and is preserved in SAS-induced responses. More unperturbed pitch height is observed in pitch-trained speakers’ responses than in general Mandarin speakers’ responses. While slight and limited elevation may occur at the beginning of SAS-induced responses, the preservation of the absolute pitch height appears to interact with intended response durations. The results suggest that absolute pitch height, even when not acting as a phonemic parameter, can be pre-specified in speech plans and released by a SAS both rapidly and accurately.

Impact of in vitro digestion phases on the stability and bioaccessibility of carotenoids and their esters in mandarin pulps.

The composition of carotenoids (carotenes and free and acylated xanthophylls) and their bioaccessibilities were determined for the first time in pulps of mandarins cultivated in Brazil. Two cultivars of mandarin, Citrus reticulata Blanco cv. 'Ponkan' and Citrus reticulata × C. sinensis cv. 'Murcott', showed higher contents of most carotenoids compared to those found in C. deliciosa Tenore cv. 'Rio'. The major carotenoids in mandarin cv. 'Ponkan' and 'Murcott' were (all-E)-β-cryptoxanthin laurate (19-21%), (all-E)-β-cryptoxanthin myristate (15-17%) and (Z)-ζ-carotene (7-12%), followed by (all-E)-β-cryptoxanthin palmitate (4-7%), free (all-E)-β-cryptoxanthin (5-6%) and (all-E)-β-carotene (4-5%), while in mandarin cv. 'Rio' (all-E)-β-cryptoxanthin myristate (22%) was the major compound, followed by (all-E)-β-cryptoxanthin laurate (16%), (all-E)-β-cryptoxanthin palmitate (11%), (all-E)-β-cryptoxanthin (9%) and (all-E)-β-carotene (6%). After in vitro digestion, the qualitative carotenoid profile of the supernatant containing the micellarized carotenoids was similar to that of fresh fruits, but the contents were significantly lower. Carotenoid and mandarin physico-chemical properties influenced the bioaccessibility of carotenoids. Free (all-E)-β-cryptoxanthin showed the highest bioaccessibility in all mandarin cultivars (33-42%), while the bioaccessibilities of β-carotene (16-36%) and the major carotenoid esters (18-33%) were lower. The overall recovery of carotenoids during in vitro digestion was around 98% after the oral phase, 79% after oral + gastric phases and 77% after oral + gastric + duodenal phases, with free (all-E)-β-cryptoxanthin and (all-E)-β-carotene being the most stable ones. Besides possible E-Z isomerization and ester hydrolysis, evident losses occurred in total carotenoid contents and also in the most individual carotenoids and they were not compensated for by the former reactions.

Response of some beneficial insect species to colored sticky traps in citrus

Colored sticky traps have been commonly used for the sampling of detrimental insect species worldwide. However, there is no information about the catches of non-target insects such as predaceous and pollinating insects by colored traps. In this study, trials with colored sticky traps (white, yellow, blue and green) in mandarin cv Okitsu (Satsuma) trees were carried out during 2011 and 2012 in Adana Province, Turkey. Colored plates were hung, at about 1.7 m above ground level, from the exterior canopy of the selected trees and were positioned to the four cardinal directions. A total of 15 beneficial insect species were captured on various colored plates. Yellow and green traps were more attractive to the coccinellid, Oenopia conglobata (L., 1758), than the other colored traps. Significantly more of the predaceous hoverfly, Episyrphus balteatus (De Geer, 1776) and the honey bee, Apis mellifera L., 1758 were obtained on white traps. Green and blue traps were the least attractive to A. mellifera . The yellow, blue and green traps hung on the west side of the trees captured significantly more beneficial insects, but white traps hung on the south sides of outer branches trapped considerable numbers of E. balteatus and O. conglobata . White and yellow sticky traps may provide more ecological data for beneficial insects.

Studies on physico-chemical constituents in different cultivars of citrus fruits under Lucknow condition, India

The physico-chemical studies were conducted on the citrus fruits of sweet orange cv. Mosambi Local-1, 2, 3, 4 and 5 and Sweet Mandarin cv. Chinese Orange, Kinnow, Nagpur Mandarin, Local Mandarin-1 and Local Mandarin- 2. The Sweet Orange cultivar was highest size in Mosambi Local-3 with maximum fruit volume 204 ml and flesh weight 139.66 g followed by Mosambi Local-4. The juice recovery percent was maximum in Mosambi Local-3 28.63 and the highest specific gravity was found in Mosambi Local-1 (0.99) followed by Mosambi Local-2 (0.94). The different cultivars of Sweet Orange were recorded varies from the total soluble solid 7.60 to 12.66 percent, reducing sugar 4.13 to 7.08 per cent, total sugar 5.90 to 10.12 per cent, tritrable acidity 0.52 to 0.83 per cent, ascorbic acid 46 to 74.80 mg/100g and pH 3.92 to 4.98. The juice percent was determined in Kinnow 53.20 g after that Nagpur santra 51.30 g. The chemical attributes of Sweet Mandarin were found as total soluble solid varied from 8.96 to 12.20 per cent, reducing sugar 3.22 to 6.60 per cent, total sugar 5.73 to 10.04 per cent, titrable acidity 0.84 to 2.24 per cent, ascorbic acid 25.96 to 36.13mg/100 g and pH 3.84 to 4.60. However, the Sweet Orange cultivars Mosambi Local-3 and Mosambi Local-4 and Sweet Mandarin cv. Local Mandarin-1 were suitable for export, making of non alcoholic beverages, easy for bottling and frozen products grown under Lucknow conditions.

Visible–NIR reflectance spectroscopy and manifold learning methods applied to the detection of fungal infections on citrus fruit

The development of systems for automatically detecting decay in citrus fruit during quality control is still a challenge for the citrus industry. The feasibility of reflectance spectroscopy in the visible and near infrared (NIR) regions was evaluated for the automatic detection of the early symptoms of decay caused by Penicillium digitatum fungus in citrus fruit. Reflectance spectra of sound and decaying surface parts of mandarins cv. ‘Clemenvilla’ were acquired in two different spectral regions, from 650nm to 1050nm (visible–NIR) and from 1000nm to 1700nm (NIR), pointing to significant differences in spectra between sound and decaying skin for both spectral ranges. Three different manifold learning methods (principal component analysis, factor analysis and Sammon mapping) were investigated to transform the high-dimensional spectral data into meaningful representations of reduced dimensionality containing the essential information. The low-dimensional data representations were used as input feature vectors to discriminate between sound and decaying skin using a supervised classifier based on linear discriminant analysis. The best classification results were achieved by employing factor analysis on the NIR spectra, yielding a maximum overall classification accuracy of 97.8%, with a percentage of well-classified sound and decaying samples of 100% and 94.4%, respectively. These results lay the foundation for the future implementation of reflectance spectroscopy technology on a commercial fruit sorter for the purpose of detecting decay in citrus fruit.

Effects of chitosan coatings on physicochemical and nutritional quality of clementine mandarins cv. ‘Oronules’

A commercial solution of chitosan was applied on mandarins 'Oronules' at different solid content (0.6%, 1.2% and 1.8%). Additionally, one group of mandarins was coated with a polyethylene-shellac commercial wax, and another group remained uncoated (control). Mandarins were stored at 5 °C up to 28 days followed by 7 days at 20 °C simulating retail conditions. One group of mandarins was stored at 20 °C for 9 days simulating direct retail conditions. The commercial wax decreased weight and firmness loss of mandarins compared to uncoated samples, whereas the chitosan coating did not effectively decrease weight loss of mandarins. Chitosan-coated mandarins at the highest solid content retained firmness after cold storage and contained more phenolics than uncoated ones. Although all the coatings restricted gas exchange and modified the internal atmosphere of the mandarins, with a greater effect at higher chitosan concentration, sensory quality was not affected. In general, the internal quality and the health-related properties of mandarins were not negatively affected by coating application. However, there is a need to further improve the water barrier properties of the chitosan coating.

Microwave vacuum drying of osmotically dehydrated mandarin cv. (Sai-Namphaung)

Mandarin [mandarin cv. (Sai-Namphaung)] was subjected to osmotic dehydration prior to microwave vacuum drying. Osmotic solutions were varied using different ratios of sucrose to glycerol (9:1, 7:3 and 5:5 w/w). Because of the decreased moisture content and solid gain during osmotic dehydration, dielectric properties of mandarin were changed significantly (P ≤ 0.05). The osmotically dehydrated mandarin was then dried further using microwave vacuum drying at 4.8 and 6.4 W g−1. Among thin layer models, page model was the best to describe the drying of osmotically dehydrated mandarin. An increase in the microwave power could increase drying rate without significant effect on hardness of dried samples. Nonetheless, the hardness was significantly (P ≤ 0.05) reduced by an increase in the glycerol ratio in the osmotic solution. The increase in microwave power and glycerol ratio significantly (P ≤ 0.05) decreased β-carotene content and thereby affected colour of the dried mandarin.