Xanthan gum coatings augmented with lemongrass oil preserve postharvest quality and antioxidant defence system of Kinnow fruit under low-temperature storage.

Kinnow mandarin is an important citrus fruit that undergoes various postharvest qualitative losses. Therefore, the present study aimed to investigate the effect of polysaccharide-based xanthan gum (XG) coatings and lemongrass essential oil (LG) on the nutritive quality of Kinnow mandarins stored at 5-7 °C, 90-95 % RH for 75 days. The results revealed that in comparison to control the coatings maintained the fruit titratable acidity (TA), soluble solid content (SSC), ascorbic acid (AsA) content, total flavonoid content (TFC), and juice content, along with reduced weight loss and spoilage incidence. The coated fruits also exhibited higher sensory quality, total antioxidant activity (TAA), and activities of enzymes; catalase (CAT), peroxidase (POD), and phenylalanine ammonia-lyase (PAL). At the end of storage, the fruits coated with XG 1.0 % + LG 1.0 % exhibited maximum TA (0.69 %), AsA content (203.5 mg L-1), and TFC (0.21 mg g-1) with minimum weight loss (7.57 %) and spoilage (3.01 %) and SSC (11.87 %). The scanning electron microscopic (SEM) images of the coated fruits also exhibited smooth surfaces with closed stomata pores. Overall, XG 1.0 % + LG 1.0 % proved as a potential postharvest treatment for maintaining the nutritive quality of Kinnow under low-temperature storage.

Role of gum Arabic combined with cinnamic acid coating on quality and cell wall degradation enzymes of mango fruits at low temperature.

Mango exhibits a short shelf life when kept under ambient conditions. Therefore, this study was carried out to assess the synergistic effect of gum Arabic (GA) and cinnamic acid (CA) coatings on mango fruits stored for 28 days at 12 ± 1 °C. The treatments included GA 10 and 20 % sole and its formulation with CA 0.2 % while the uncoated fruits were used as control. The results revealed that GA + CA coatings exhibited reduced weight loss, flesh firmness, delayed respiratory peak, retained soluble solids content (SSC), titratable acidity (TA) and skin colour, retarded spoilage, and decreased electrolyte leakage of fruit as compared to uncoated fruit during storage. Among all, the coating GA 20 % + CA 0.2 % maintained higher firmness (16.6 N), SSC (20.1 %), TA (0.71 %), total flavonoid content (152 mg/kg) and total carotenoids content (45.1 mg/kg) and retained the higher sensory quality of mango fruit at the end of storage. Additionally, the GA 20 % + CA 0.2 % coating suppressed activities of polygalacturonase (PG), cellulase (CL) and pectin methyl esterase (PME) in stored mango fruits.

Composite coating of chitosan with salicylic acid retards pear fruit softening under cold and supermarket storage.

Fruit softening is enzyme mediated degradation process determined by the action of cell wall modifying enzymes. Present study evaluated the combined effects of chitosan (CH) and salicylic acid (SA) coatings in modulation of fruit softening enzymes in Punjab Beauty pear (Pyrus pyrifolia × Pyrus communis) fruit stored under cold (0-1 °C and 90-95 % RH) and supermarket (20-22 °C and 80-85 % RH) conditions. Composite CH + SA coatings reduced mass loss and retained fruit firmness throughout the 67 and 20 days storage period. In addition, CH + SA prevented membrane damage by suppressing the electrolyte leakage and malondialdehyde (MDA) accumulation as compared to CH or SA alone. CH 2.0 % + SA 2.0 mM coating efficiently delayed the cell wall degrading enzymatic activities including pectin methylesterase (PME), polygalacturonase (PG) and cellulase associated with fruit softening up to 60 and 15 days storage period in cold and supermarket conditions, respectively.

Efficacy of postharvest sodium nitroprusside application to extend storability by regulating physico-chemical quality of pear fruit.

Quality loss in pear fruit during storage reduces its marketability for long run. To increase its storability, the efficacy of postharvest dip treatment donor sodium nitroprusside (SNP) 0.000, 0.001, 0.002 and 0.003 mol L-1 were investigated on pear fruit cv. Patharnakh under storage conditions (low temperature 0-1 °C and relative humidity (90-95%). SNP effectively lowered fruit mass loss, retained colour and higher firmness, suppressed browning and respiration rate and sustained soluble solids content, titratable acidity, total phenol content and ascorbic acid thus conserved the fruit quality for longer period. SNP treatments suppressed the activity of polyphenol oxidase and increased activity of superoxide dismutase enzyme. Additionally, the SNP treated fruit exhibited lesser activities of fruit softening enzymes like pectin methylesterase, polygalacturonase and cellulase. Among all, 0.002 mol L-1 SNP concentration was superior to lengthen storability and sensory quality of pear up to 60 d under cold storage.

Effect of sodium benzoate application on quality and enzymatic changes of pear fruits during low temperature.

Effect of postharvest applications of sodium benzoate on physico-chemical properties and enzymatic activities of pear fruit cv. Patharnakh during cold storage were examined. Uniform and healthy fruits of pear cv. Patharnakh were treated with sodium benzoate (0.0, 1.0, 2.0 and 3.0%) and thereafter stored at low temperature conditions (0-1 °C and 90-95% RH) for 70 days. Evaluation of physico-chemical parameters and enzymatic activities were made at 0, 20, 40, 60 and 70 days of storage. Sodium benzoate treatments effectively retained higher fruit firmness, sensory quality, total phenolics content and alongside suppressed the degradation of total soluble solids, ascorbic acid content and titratable acidity. Sodium benzoate treated fruits also exhibited higher efficacy in maintaining less enzymatic activity of cellulase, pectin methyl esterase and polyohenol oxidase. It was inferred that the postharvest treatments of sodium benzoate proved to be an effective means of improving quality and postharvest life of 'Patharnakh' pear fruit.

Influence of pre-harvest sprays of calcium nitrate on storability and quality attributes of plum fruits.

The effects of pre-harvest applications of calcium nitrate at different concentrations were investigated on storability and quality attributes of plum fruits under low temperature storage. Uniform and healthy trees of plum cv. Satluj Purple were sprayed with calcium nitrate (1.0%, 1.5% and 2.0%) in 2nd and 3rd week of April and control trees were water sprayed only. Fruits from treated and control trees were harvested at colour break stage, and then stored at low temperature conditions (0-1 °C and 90-95% RH) for 35 days. Evaluation of physico-chemical parameters and enzymatic activities were made on the day of harvest and after 7, 14, 21, 28 and 35 days of storage. The colour of the fruits with respect to a* and b* values (green-red and blue-yellow spectrum, respectively) improved progressively up to 35 days of storage, whereas, fruit firmness decreased. Total sugars and pectin methylesterase (PME) and cellulase activities increased up to 28 days of storage before showing a declining trend. Two superimposed sprays of calcium nitrate (2.0%) enhanced the storage life of plum fruits up to 28 days by reducing physiological loss in weight (PLW), PME and cellulase activities, delaying development of fruit colour & anthocyanin and retaining sensory quality, firmness and total sugars in plum fruits.

Evaluation of plum fruit maturity by image processing techniques.

Maturity is the key factor which determines the storage life and ripening quality of fruits. In order to provide marketing flexibility and to guarantee the acceptable eating quality to the buyer it is very critical to determine the right maturity stage. Maturity indices are also important for trade regulation, marketing strategy and for the efficient use of labor and resources. The proposed system is based on implementation of image processing techniques on the JPEG images of different maturity stages of the plum variety 'Satluj Purple' grown under sub-tropical conditions. The external quality features like color, texture and size were analyzed. Color feature was extracted by using mean RGB values. Entropy, Local Binary Pattern and Discrete Cosine transformation were used for extracting textural features. Correlation coefficients between images of various categories were recorded to determine the most dominant factor for classification. Multi-Attribute Decision Making theory was used for taking final decision. The developed system accurately determined the maturity level. Color was found to be the most dominant factor for classifying the plums according to maturity level. The error percentage was less than 2.4%, when the length and width computed from application were compared with the manual readings. When RGB indices of fruit images were correlated with chemical properties of fruits, strong association was found between fruit acidity and mean intensity of green color (R2 = 0.9966). Significant variability in total soluble solids was also explained by variation in R/G ratio (R2 = 0.8464).

Ripening quality of Dusehri mango in relation to harvest time.

The effect of different harvesting time on ripening quality of mango cv. Dusehri was investigated under sub-tropics of northwestern India. Fruits were harvested at 101, 106 and 111 days after fruit set (DAFS) and kept at 25 °C in temperature controlled chamber for ripening. Fruits were analyzed periodically for physico-chemical characteristics at the time of harvest (0 h) and after 72, 96 and 120 h of ripening period. With advancement in ripening period, an increase in physiological loss in weight, soluble solids content (SSC), sensory quality rating, ß-carotene and pulp colour development of mango fruits was recorded. While a decline in fruit firmness and titratable acidity (TA) was observed with ripening period. Fruits picked at 111 DAFS recorded highest SSC (8.01%), sensory rating (4.67), ß-carotene (0.427 mg/100 g) vis-à-vis lowest fruit firmness (15.3 lbf) and TA content (1.56%). The luminosity of fruit pulp decreased with the storage period. The redness and yellowness of the fruit pulp represented by a* and b* values, respectively increased with delay in harvesting period. The rate of ripening was rapid in late harvested fruits as compared to early harvested fruits. After 96 h of ripening period, fruits harvested at 111 DAFS showed very much desirable quality whereas fruits harvested at 101 DAFS showed moderately desirable quality. Results showed that harvesting of mango fruits can be extended to 111 days and such fruits attained optimum ripening quality after 96 h at 25 °C.

Transitions in mesocarp colour of mango fruits kept under variable temperatures.

The impact of variable temperatures on mesocarp colour development and physico-chemical changes of mango fruits cv. Langra during ripening has been investigated. Physiological mature mango fruits were kept in temperature regulated chambers (20 and 25 °C) and at room temperature (29.8-33.6 °C). Progress in development of mesocarp colour, ß-carotene, sensory quality (SQ) and total soluble solids (TSS) content of fruits were analysed periodically from 48 to 168 h of ripening period. The progress of ripening period was accompanied by an overall increase in colorimetric value redness (a*), yellowness (b*), chroma or saturation (C*), a reduction in lightness (L*) and hue angle (h0) values. Colour development was found to be more in fruits ripened at higher temperatures than the fruits at lower temperature. ß-carotene content of pulp improved with ripening of fruits up to 120 h of ripening period. Fruits ripened at 25 °C recorded maximum sensory quality score. Pearson's correlation matrix studies revealed that fruit mesocarp colour a*, b*, C* values were directly correlated with ß-carotene, SQ and TSS with progress of ripening period.

Physico-chemical changes during progressive ripening of mango (Mangifera indica L.) cv. Dashehari under different temperature regimes.

The effect of different temperature regimes on ripening quality of mango cv. Dashehari was investigated. Fruits were kept at 20, 25 °C in temperature controlled chambers and at room temperature. Fruits were analyzed periodically for physico-chemical characteristics after every 24 h interval up to 168 h of ripening period. Development of soluble solid contents (SSC), flesh softening and physiological loss of weight of fruits occurred progressively during ripening. Progression of ripening changes in fruit were found to be less at 20 and 25 °C than at room temperature. ß-carotene content of pulp improved with ripening but declined after 144 h. Sensory quality (SQ) of mangoes ripened at lower temperature maintained for longer duration and were more acceptable than fruits ripened at room temperature. Pearson's correlation matrix studies showed the inverse relationship of quality parameters SSC, ß-carotene and SQ with firmness and titratable acidity during progressive ripening of fruits. Further, principal component analysis for extensive view of changes in quality parameters and their contribution to overall variability revealed that sensory quality (F1) contributed to maximum variation in ripening indices of fruit.

Enzymatic changes in plum (Prunus salicina Lindl.) subjected to some chemical treatments and cold storage.

The objective of the present work is to see the effect of different chemical treatments on pectin methylesterase (PME) activity and softening of the fruits. Purple plums (cv. Satluj) fruits were harvested at colour break stage and treated for 5- minutes in aqueous solutions of salicylic acid at 138, 276 and 414 ppm, Ascorbic acid at 10,000, 20,000 and 30,000 ppm, and Gibberelic acid at 20, 40 and 60 ppm. For control the fruits were dipped in distilled water. Treated fruits were stored at low temperature conditions for 40 days. Physico chemical characteristics and PME activity were determined at 10 day interval. The colour of the fruits improved with respect to a* and b* values progressively throughout the storage, whereas, fruit firmness decreased. Total sugars and PME activity increased before showing a declining trend. Pre-storage application of salicylic acid (414 ppm) significantly delayed colour development. Fruits treated with salicylic acid (414 ppm) retained highest firmness, total sugars and PME activity at the end of storage.