Preharvest salicylic acid treatments to improve quality and postharvest life of table grapes (Vitis vinifera L.) cv. Flame Seedless.

Significance of preharvest salicylic acid (SA) treatments on maturity, quality and postharvest life of grape cv. Flame Seedless were studied during two years. The experiment was performed on 12-year old own rooted, grapevines planted at 3 m × 3 m spacing trained on overhead system. Vines were treated with aqueous solutions of SA (0.0, 1.0, 1.5 and 2.0 mM) at pea stage and at veraison. After harvesting, clusters were divided into two lots in which one was subjected to initial quality evaluation, while the other was stored in cold room (3-4 °C, 90-95 % RH) for evaluation of postharvest quality. SA at the dose of 1.5 and 2.0 mM hastened berry maturity by 3 to 5 days, produced less compact bunches alongside larger berries in contrast to control and the lowest dose. The same doses effectively maintained peel colour, higher firmness, lower pectin methyl esterase activity and electrolyte leakage alongside suppressing degradation of TSS and TA during cold storage. These two doses also exhibited higher efficacy on maintaining anthocyanins, phenols and organoleptic properties while reducing weight loss, rachis browning and decay incidence. Correlation analysis demonstrated that many quality parameters are interdependent. In conclusion, preharvest spray of 1.5 mM SA proved to be an effective means of improving quality and extending postharvest life of grape cv. Flame Seedless.

Effect of different packaging films on shelf life and quality of peach under super and ordinary market conditions.

Peach (Prunus persica L. Batsch) fruits of cultivar 'Shan-i-Punjab' were harvested at colour break stage and packed in paper moulded trays followed by wrapping with different packaging films viz. cryovac heat shrinkable RD-106, cling and low density polyethylene (LDPE) film. After packaging, the fruits were stored under two different conditions i.e. super-market conditions (18-20 °C; 90-95 % RH) and ordinary market conditions (28-30 °C; 60-65 % RH). The fruits were evaluated for various quality attributes periodically. The shrink film helped in reducing the loss in weight, firmness, decay incidence and maintained the various qualities attributes like total soluble solids, sugars, acidity and ascorbic acid content of the fruits during shelf-life better than unwrapped control fruits. The pectin methyl esterase enzyme activity was also found to be lower in shrink film packed fruits over the unwrapped control fruits. The in-package gaseous composition (O2 and CO2) in shrink film packed fruits was found to be at desired level which resulted in maintenance of pleasant flavour of the fruits. On the other hand LDPE film accumulated very high level of CO2, which led to formation of fermenting odour and decay of fruits in the package. The data revealed that RD-106 film proved quite effective in prolonging the shelf-life and maintaining the quality of peach fruits for 9 and 4 days under super market conditions (SMC) and ordinary market conditions (OMC), respectively as against 6 and 2 days only in case of unpacked control fruits under both the marketing conditions. The results suggest that shrink film could be used in packaging of peach without negative effects on quality.

Changes in pectin methyl esterase activity with different packaging materials and stages of fruit harvesting during cold storage of pear cv. Punjab beauty.

Pear cv. Punjab Beauty has become quite popular in Punjab. Excessive softening during cold storage leading to low shelf life is the major factor limiting its wider adoption. Studies were, therefore, conducted to determine the firmness and pectin methyl esterase (PME) activity at 4 harvest dates (2nd, 3rd and 4th week of July, and 1st week of August). Various packaging materials i.e. corrugated fiber board boxes and crates with high and low density polyethylene liners, corrugated fiber board boxes, crates and wooden boxes were also evaluated for their role in extending the shelf life of fruits. The enzyme activity and fruit firmness was evaluated periodically after 30, 45, 60 and 75 days of storage at 0-1 °C and 90-95 % RH. The firmness of the fruits decreased with the increase in storage intervals but the enzyme activity increased with the storage period up to 60 days and declined thereafter. Ripening-related changes in all the harvests were characterized mainly by an increase in the solubilization of pectin with a concomitant decrease in the degree of firmness. There was a continuous increase in enzyme activity with the advancement in harvesting dates and then fell sharply in the advanced ripening stages. Highest pectin methyl esterase activity was in fruits packed in crates followed by wooden boxes and corrugated fiber board boxes while the lowest was recorded in fruits packed in corrugated fiber board boxes with high density polyethylene liners. Therefore, high density polyethylene lined CFB boxes proved to be most effective in preventing the loss in firmness.

Development of post-harvest protocol of okra for export marketing.

The study was carried out on the harvesting and handling methods of okra with the objective to maintain the best quality of pods from harvesting to end consumer especially for export marketing. For that purpose okra cv. 'Punjab-8' pods were harvested with minimum handling (least injuries to the pubescence on the ridges of pod) and normal handling (no safety taken to prevent injuries on pods). Pods were precooled at 15 ± 1ºC, 90-95% RH; jumble packed in the CFB boxes of 2.0 Kg capacity and than stored at 8 ± 1ºC, 90-95% RH. The quality parameters of okra namely texture, chlorophyll content, physiological loss in weight, rotting percentage and general appearance were studied. The pods harvested with minimum handling and field packaging can retain their green colour, crisp texture (maximum force to puncture pod = 500.2 g) with minimum rotting (3.0%) and physiological loss in weight (15.8%) and good appearance upto 13 days of cold storage whereas normal handled pods can be stored upto 5 days at 8 ± 1ºC, 90-95% RH and thereafter lost their general appearance on the 7th day of storage and were discarded. Therefore, in order to maintain high quality of okra from harvesting to the final destination (consumer), the okra pods should be harvested with minimum handling followed by field packaging in CFB boxes.

Effect of different packaging materials and storage intervals on physical and biochemical characteristics of pear.

The fruits of semi-soft pear (Pyrus communis) cv. Punjab Beauty harvested at physiologically mature stage in 3rd week of July were packed in corrugated fiberboard boxes (CFB) with low density polyethylene (LDPE) liners, CFB with high density polyethylene (HDPE) liners, crates with LDPE liners, crates with HDPE liners, CFB, crates and wooden boxes and stored in walk-in-cool chamber at 0-1 °C and 90-95% RH. The fruits were analyzed after 30, 45, 60 and 75 days for physiological loss in weight (PLW), fruit firmness, core browning, spoilage, total soluble solids (TSS), juice acidity and sensory quality. The PLW was maximum in crates while the spoilage was maximum in fruits packed in wooden boxes. Core browning was more in fruits packed in crates and CFB boxes with LDPE liners while minimum was in fruits packed in CFB boxes. However, core browning did not occur up to 45 days of storage in any of the package. Fruits packed in CFB boxes with HDPE liners effectively reduced the weight loss, spoilage and retained acceptable firmness up to 75 days of storage with maximum edible quality. TSS and sugars were maximum in fruits packed in wooden boxes while the acidity was maximum in CFB boxes with HDPE liners. The fruits in CFB boxes with HDPE liners maintained the perfect balance between sugars and acids up to 75 days of storage.

Effect of shrink wrap packaging for maintaining quality of cucumber during storage.

Immature green cucumber cv. 'Padmini' fruits were individually shrink wrapped with Cryovac D955 (60 guage) film and stored at 12 ± 1 °C, 90-95% RH as well as ambient conditions (29-33 °C, 65-70% RH). At 12 ± 1 °C and 90-95% RH, individual shrink wrapped cucumber recorded minimum Physiological loss in weight (0.66%) as compared with unwrapped fruits (11.11%) at the end of refrigerated storage (15 days). The softening (loss of firmness) was maximum (1304.6-876.6 g force) in unwrapped cucumbers whereas in shrink wrapping, minimum loss in firmness (1304.6-1065.3 g force) was observed after 12 days storage at 12 ± 1 °C and 90-95% RH but greater loss of weight and firmness makes the control cucumbers unmarketable after 9 days of storage. There were no rotting at all both in shrink wrapped and unwrapped cucumbers upto 15 days of storage at 12 ± 1 °C and 90-95% RH. After 15 days storage of shrink wrapped cucumbers at 12 ± 1 °C and 90-95% RH, there was loss of green colour and development of yellowness and decay. The sensory attributes score was highest in shrink wrapped cucumbers as compared to unwrapped cucumbers at end of both storage conditions. Thus it can be concluded that individual shrink wrapped cucumber can be stored well upto 15 days at 12 ± 1 °C and 90-95% RH and for 5 days at ambient conditions (29-33 °C, 65-70% RH) with maximum retention of green colour, no spoilage, minimum weight and firmness loss and very good sensory quality attributes whereas, unwrapped fruits can be stored well upto 9 days at 12 ± 1 °C and 90-95% RH and for 2 days at ambient conditions with maximum retention of physico-chemical quality attributes.

Effect of packaging on storage life and quality of cauliflower stored at low temperature.

Medium sized cauliflower (Brassica oleracea var. botrytis) curds after removing outer leaves, sorting and without washing were packed in different packaging films and stored at 0 ± 1°C, 90-95% RH. Changes in curd colour, texture, physiological loss in weight, spoilage and sensory quality were evaluated at weekly interval upto 28 days. Cauliflower curds individual packed in high density polyethylene bags (20 µm) with perforation (6 holes/bag) can be stored up to 21 days at 0 ± 1°C and 90-95% RH with maximum retention of white colour of curd, minimum spoilage, weight and firmness loss and good sensory quality attributes. The use of cling wrap films should be avoided as this leads to accumulation of excessive moisture resulting in huge spoilage loss.

Studies on optimization of ripening techniques for banana.

Fruits of banana (Musa spp) cultivar 'Grand Naine' were harvested at physiological green mature stage. The first lot of fruit was exposed to ethylene gas (100 ppm) for 24 h in ripening chamber. The second lot was treated with different concentrations of aqueous solution of ethephon (250, 500, 750, 1000 ppm) each for 5 min. The fruits were packed in plastic crates and stored in ripening chamber maintained at 16-18°C and 90-95% RH. Treatment with ethylene gas (100 ppm) or ethephon (500 ppm) resulted in adequate ripening of fruits after 4 days with uniform colour, pleasant flavour, desirable firmness and acceptable quality and better shelf-life. The untreated control fruits were hard textured and poor in colour and quality. The ripening with ethylene gas or ethephon treatment seems to hold promise in reducing postharvest losses and boosting the economy of banana growers and traders.

Effect of 1-methylcyclopropene (1-MCP) on storage life and quality of pear fruits.

Pear (Pyrus pyrifolia (Burm) Nakai) fruits of cultivar 'Patharnakh' were harvested at optimum maturity and treated with 500, 750 and 1000 ppb concentration of 1-MCP gaseous vapours for 4 h in a closed chamber maintained at 20°C. After treatments the fruits were packed in corrugated fibre board cartons and stored at 0-1°C and 90-95% RH. Fruits treated with 1000 ppb 1-MCP recorded minimum weight loss, maintained acceptable firmness and quality attributes till 75 days of storage. The stored fruits also retained post-storage shelf life for 3 days at ambient conditions (30-35°C and 60-65% RH) and 6 days at supermarket conditions (20°C and 85-90% RH).

Effect of pre-harvest calcium sprays on post-harvest life of winter guava (Psidium guajava L.).

Influence of pre-harvest foliar application of calcium nitrate on quality attributes of winter guava cv. 'Sardar' during different interval of cold storage and post cold storage shelf-life under ambient conditions was investigated. Plants were sprayed with calcium nitrate solutions (0.5, 1.0 and 1.5%) at colour break stage of fruit and a fruit with no treatment was control. The fruits were harvested at optimum maturity. Bruise and disease free fruits were packed in corrugated fibre board boxes with newspaper lining and stored at 6-8 °C and 90-95% RH. The fruits were evaluated after 10, 20, 30 and 40 days of storage and during shelf-life at 2 and 4 days interval. Physiological loss in weight and spoilage of fruits increased and firmness, ascorbic acid and acidity decreased continuously during storage. Fruits treated with 1% Ca(NO3)2 effectively reduced spoilage, maintained higher firmness, total soluble solid and ascorbic acid up to 2 days under ambient conditions after 30 days of cold storage and remained moderately acceptable up to the 40 days of storage.