Effects of sorbitol concentration and packaging material on quality of carrot candy during storage

Introduction

The health and nutritional benefits of the carrot, its commercialization and industrialization in the form of different products is very important in fulfilling the nutrient requirements of the people particularly as a cheap source of vitamin A. It also contains a good source of ascorbic acid, vitamin K, dietary fiber and potassium. There is an appreciable amount of vitamin B 1 , B 2 , B 6, B 12 and minerals. Carrot contains 86 percent moisture, 10.6 g carbohydrates, 0.2 g fat, 1.2 g fiber, 1890 µg carotene, 0.04 g thiamine, 0.02 g riboflavin, 0.6 g niacin, 530 mg phosphorus, 1.1 g minerals and 3 mg per 100 g vitamin C (Gopalan et al. 2004) [10] . Moreover, carrots are known to contribute 14 to 17 percent of the total vitamin A consumption (Heinonen 1990 and Block, 1994) [11,6] . Carotenoid helps in preventing heart diseases, improve vision, help in reducing blood sugar and reduce colon cancer (Bast et al. 1998 and Bramley 2002) [5,7] . Carrots are being consumed in various forms viz., salad, soup, stews, curries, pies and sweetmeats. They are cooked and processed into various value added products viz., canned carrots, chips, kheer, halwa, powder, juice, beverages, wine, preserve, intermediate moisture products like, jam etc. but a present not being used for candy preparation. Candy is a sweet product prepared from fruits or vegetables by impregnating them with sugar syrup followed by draining of excessive syrup and then drying the product to a shelf stable state. The maintenance of colour, texture, taste and aroma are major problems in preparation of candy. There is urgent need to standardize the process for preparation of candy from carrots. The use of humectants could be applied to prevent this problem. Sugar alcohols, such as, sorbitol and maltitol are bulk sweeteners with good taste and reduced calories. So, the present investigation was carried out to study the effect of sorbitol as a humectant and packaging materials on quality of carrot candy.

Experiment was carried out in Centre of Excellence on Post Harvest Technology, Department of Post Harvest Technology, ASPEE College of Horticulture and forestry, N.A.U., Navsari.

Experimental Details

Carrot candy was prepared using different concentrations of humectant and different packaging materials. A total of 15 different treatment combinations used in experiment as detailed in Table 1 were comprised of two different factors. The detail of treatment factors and treatment combinations are given ahead. The experiment for preparation of carrot candy was carried out with three repetitions.

Methodologies for Candy preparation

The carrots were washed with running tap water. The carrots were cut into 15×15mm ± 1mm pieces followed by blanching at 85 o C for 3 minutes. After that blanched carrot pieces were given osmotic dip treatment for overnight using 50 o Brix sugar syrup containing 1000 ppm potassium metabisulphite (KMS) and 2000 ppm citric acid. After 24 hours, syrup was drained out; TSS and weight of syrup were recorded. The TSS of drained out syrup was raised 10 o Brix by adding table sugar and then pieces were again kept in syrup for overnight. The process was repeated till the TSS of syrup reached to 70 o Brix. Then pieces were rinsed in luke warm water and drained followed by coating with different concentrations of humectant i.e. sorbitol (5, 10, 15 and 20%) for 10 seconds. After coating treatments pieces were dried in hot air cabinet tray drier at temperature of 60 °C for 8 hours. After dehydration, samples of carrot candy were packed in the different packaging materials (polyethylene, polypropylene and aluminium laminate), sealed air tight and stored at room temperature for further analysis and to record observations. Principal steps used for preparation of carrot candy have been presented in Fig 1.

Quality parameters

Ten carrots were selected randomly from the whole lot for determining the physical characteristics. The moisture was estimated by drying the weighted samples in hot air oven at 70±2 °C to a constant weight (AOAC, 1984) [3] . The total soluble solids (TSS) of the samples were determined with the help of hand refractometer and expressed as °Brix (Ranganna, 1997) [27] . The titratable acidity, sugars, ascorbic acid and crude fibre content were determined by the method as detailed by Ranganna (1997) [27] . Proteins and betacarotene contents were determined by method as detailed by Sadasivam and Manickam (1996) [29] . The candy was evaluated for sensory qualities on the basis of overall acceptability by a panel of 7-10 judges on a 9-point Hedonic scale (Amerine et al. 1965) [2] . The data pertaining to physico chemical characteristics of candy were analysed statistically by following completely randomized design (Panse and Shukhatme, 1967) [20] .

Result and Discussion

Physico-Chemical Attributes of Fresh Carrots

The physico-chemical characteristics of fresh carrots which were used for the preparation of fresh-cut carrot pieces, candy and instant carrot halwa mix powder are given in Table 2. The data on physical parameters of fresh carrots revealed the mean weight, peeling and trimming losses of the carrots in the range of 75.45 g and 7.40 percent having orange colour of skin/peel and flesh. The data on chemical parameters of carrots revealed mean moisture, TSS, acidity, reducing sugars, non-reducing sugars, total sugars, betacarotene, proteins, crude fibre, ascorbic acid in the range of 9.53 o Brix, 0.12%, 2.74%, 4.15%, 6.89%, 38.65 mg/100 g, 0.95%, 1.80% and 3.91 mg/100 g, respectively. Our result in present investigation for physico-chemical parameters of carrots are similar to earlier studies as reported by Gopalan et al. (2004) [10] . The chemical constituents of carrot reported to contains 86% moisture with 9.55 °Brix TSS, 2.77% reducing sugars, 6.92% total sugars, 0.12% acidity, 10.6 g carbohydrates, 0.2 g fat, 1.2 g fiber, 3965 micro g beta-carotene and 3 mg per 100 g vitamin C (Gopalan et al., 2004) [10] . Sharma et al. (2012) [33] also reported similar variations for moisture (86% to 88%), carbohydrate (6 to 10.6%), crude fiber (1.2 to 2.4%), total sugars (5.6%), beta-carotenes (39.6 mg/100 g). The perusal of data pertaining to mass transfer-in and mass transfer-out for carrot candy show that candy prepared by using 1 kg of syrup (50 o B) containing 1000 ppm KMS per 1kg pieces had 12.71% mass transfer-in and 21.5% mass transfer-out during the osmotic process. It might be due to solute gain from osmotic solution of higher concentration difference. Similar reason of high concentration difference between the beetroot and osmotic solution were reported earlier by Falade and Igbeka et al.

(2007) [9] . The mass transfer-out might be due to the high osmotic strength exerts high osmotic pressure which results in exudation of higher water contents out of the cells, thus higher mass transfer-out.

Quality Parameters of candy 1. Yield of Candy

The perusal of data pertaining to yield of carrot candy has been presented in Table 2. Data showed that among different concentrations of sorbitol (humectant), yield of carrot candy (H) varied from 67.86 percent to 71.66 percent, with minimum yield in carrot candy prepared without using sorbitol (H 1 ) and maximum yield in carrot candy prepared with coating of 20% sorbitol (H 5 ). Similar observations were recorded by Naik et al. (2018) [16] for carrot candy Kishore et al. (2016) [12] for guava.

Moisture content

The perusal of data pertaining to effect of sorbitol concentrations, packaging materials, storage and their interactions on moisture content of carrot candy has been presented in Table 4. [28] for khoa. The addition of humectant resulted significant decrease in moisture content due to the incorporation of humectant such as sorbitol, sorbitol and mannitol (80:20), maltodextrin and polydextrose, and polydextrose. The moisture content reduction can be attributed to the property of binding of free water by the humectant.

Effect

Effect of packaging material: Data showed that among different packaging treatments, mean moisture content of carrot candy (P) among different packaging materials varied significantly from 13.48 percent to 13.95 percent, with minimum moisture content in carrot candy which was packed in polypropylene bag (P 2 ) and maximum moisture content in carrot candy packed in aluminium laminate bag (P 3 ). Similar observations were reported by Alam et al.

(2015) [1] for rice based snack. The higher average moisture content in aluminium laminated packaging material is due to less reduction during storage period of 6 months.

Effect of storage period: Data depicts that storage of carrot candy resulted significant decrease in mean moisture content (S) from initial value of 12.94 percent to 14.37 percent after six months of storage. Similar observations were reported by Prasad (2015) [23] for water melon rind candy. The decrease in moisture content during storage might be due to evaporation of moisture from candy due to low relative humidity in storage area and movement of moisture outside of the packaging material due to its water vapor permeability. [16] for carrot candy, Raj et al. (2015) [26] for osmo-air dehydrated apricot, Prasad (2015) [23] for water melon candy, and Nayak et al. (2012) [19] for aonla candy. The decrease in moisture might be due to evaporation of moisture from candy due to low relative humidity in storage area and permeability of the packaging material towards moisture transmission. Interactions of, P×S, H×S and were found to have significant effects, while H×P and H×P×S were found to non-significant effects.

Effect of interactions:

Water activity

The perusal of data pertaining to effect of sorbitol concentrations, packaging materials, storage and their interactions on water activity of carrot candy has been presented in Table 5. [13] and Naknaen et al. (2016) [18] for IMF banana slices.

Effect of sorbitol:

Effect of packaging material: Data showed that among different packaging treatments, mean water activity of carrot candy (P) in different packaging materials varied significantly from 0.49 to 0.53, with minimum water activity in carrot candy which was packed in aluminium laminated packaging material (P 3 ) and maximum water activity in carrot candy packed in polyethylene and poly propylene packaging material (P 1 ) and (P 2 ). Similar observations were recorded by Panwar et al. (2013) [21] for aonla slices.

Effect of storage period: Data depicts that storage of carrot candy resulted significant increase in mean water activity (S) from initial value of 0.45 to 0.60 after six months of storage. The increase in water activity during storage also observed by Swain et al. (2014) [37] , it might be due to migration of water vapour from the storage environment into the packaging material. Effects of all interactions were found significant effects.

Effect of interactions:

TSS

The perusal of data pertaining to effect of sorbitol concentrations, packaging materials, storage and their interactions on TSS of carrot candy has been presented in Table 6. [18] for cantaloupe.

Effect of sorbitol:

Increase in TSS was due to the hydrolysis of sucrose. [34] for osmo-air dried apricot. However, effect of packaging material treatments was found to have nonsignificant.

Effect of packaging material:

Effect of storage period: Data depicts that storage of carrot candy resulted significant increase in mean TSS (S) from initial value of 70.08 o Brix to 70.83 o Brix after six months of storage. The increase in TSS during storage might be attributed to conversion of polysaccharides into reducing sugars and evaporation of moisture content. Similar observations were reported by (Raj et al. 2018) [25] for water melon rind candy, (Priya and Khatakar 2013) [24] for aonla preserve, (Phisut et al. 2013) [22] for cantaloupe candy and (Prasad 2015) [23] for watermelon rind candy. [16] for carrot candy, (Raj et al.

2015) [26] for osmo-air dehydrated apricot, (Nayak et al.

2012) [19] for aonla candy, (Sood 2016) [35] for white gourd and (Attri et al. 2016) [4] for papaya. However, effects of all interactions were found non-significant.

Carotene

The perusal of data pertaining to effect of sorbitol concentrations, packaging materials, storage and their interactions on carotene content of carrot candy has been presented in Table 7.

Effect of sorbitol: Data shows that among different concentrations of sorbitol (humectant), the mean carotene content of carrot candy (H) varied significantly from 43.26 mg/100 g to 52.03 mg/100 g, with minimum carotene content in carrot candy prepared with coating of 20% sorbitol (H 5 ) and maximum carotene content in carrot candy prepared without coating of sorbitol (H 3 ). Similar observations were recorded by (Sethi and Anand 1982) [32] for carrot preserve.

Effect of packaging material: Data showed that among different packaging treatments, mean carotene content of carrot candy (P) in different packaging materials varied significantly from 45.84 mg/100 g to 50.71 mg/100 g, with minimum carotene in carrot candy which was packed in polyethylene packaging material (P 1 ) and maximum carotene content in carrot candy packed in aluminium laminated packaging material (P 3 ). Almost similar observation was reported by (Sagar and Neelavathi 2005) [30] for dehydrated carrot shred.

Effect of storage period: Data depicts that storage of carrot candy resulted significant decrease in mean carotene content (S) from initial value of 43.05 mg/100 g to 53.49 mg/100 g after six months of storage. The decrease in carotene content during storage might be attributed to its sensitivity to light and oxygen. Similar findings were earlier reported by (Mehta and Bajaj 1984) [15] for citrus peel candy and (Kumar and Sagar, 2008) [14] for osmo-dried mango slices. Effect of storage level was found to have significant. ). The decrease in carotene might be due to oxidative breakdown, isomerization or enzymatic destruction of pigments as well as increasing heating time during processing and increasing temperature at ambient condition during storage. The carotene is also sensitive to heat same as an ascorbic acid. Similar findings were earlier reported by (Naik et al. 2018) [16] for carrot candy. The interactions of H×P, H×S, P×S and H×P×S interactions were found significant effect.

Effect of interactions:

Non -enzymatic Browning

The perusal of data pertaining to effect of sorbitol concentrations, packaging materials, storage and their interactions on NEB of carrot candy has been presented in Table 8.

Effect of sorbitol: Data shows that among different concentrations of sorbitol (humectant), the mean NEB of carrot candy (H) varied significantly from 0.16 OD 440nm to 0.21 OD 440nm , with minimum NEB in carrot candy coated with 20% sorbitol (H 5 ) and maximum NEB in carrot candy prepared without coating of sorbitol (H 1 ). Similar observation was also recorded by (Sagar and Maini 1997) [31] for onion slices.

Effect of packaging material: Data showed that among different packaging treatments, mean NEB of carrot candy (P) in different packaging materials varied significantly from 0.16 OD 440nm to 0.18 OD 440nm , with minimum NEB in carrot candy which was packed in aluminium laminated (P 3 ) and packaging material and maximum NEB in carrot candy packed in polyethylene (P 1 ) and polypropylene (P 2 ) packaging materials. Similar observations were reported by (Kumar and Sagar, 2008) [14] for osmo-vac dehydrated mango slices and (Durrani et al. 2011) [8] for carrot candy.

Effect of storage period: Data depicts that storage of carrot candy resulted significant increase in mean NEB (S) from initial value of 0.14 OD 440nm to 0.21 OD 440nm after six months of storage. The increase in NEB content during storage might be due to increase of reducing sugar during storage. Increase in NEB during storage was also reported by (Nayak et al. 2012) [18] for aonla candy. [24] for aonla preserve. All interactions were found significant effects.

Effect of interactions:

Overall acceptability

The perusal of data pertaining to effect of sorbitol concentrations, packaging materials, storage and their interactions on overall acceptability of carrot candy has been presented in Table 9.

Effect of sorbitol: Data shows that among different concentrations of sorbitol (humectant), the mean overall acceptability value of carrot candy (H) varied significantly from 8.08 to 7.41, with minimum overall acceptability value in carrot candy prepared with coating of 20% sorbitol (H 5 ) and maximum overall acceptability value in carrot candy prepared with coating of 5% sorbitol (H 2 ). Similar observation was recorded by (Richa et al. 2017) [28] . Overall acceptability decreased due to pasty nature of product with an increase in the level of sorbitol in reconstituted khoa.

Effect of packaging material: Data showed that among different packaging treatments, mean overall acceptability value of carrot candy (P) in different packaging materials varied significantly from 7.72 to 7.95, with minimum overall acceptability value in carrot candy which was packed in polyethylene bag (P 1 ) and maximum overall acceptability value in carrot candy packed in aluminium laminated bag (P 3 ). Similar observation was reported by (Sutariya and Rao 2017) [36] for thirattupal. Overall acceptance scores are comprehensive evaluation of food products for acceptance. Because of decrease in all scores viz. flavour, colour and appearance and body and texture scores it was found that overall acceptability score was also affected significantly. Overall acceptability score was decreased during storage period because of loss of freshness due to moisture loss and getting dried even though sensory score was remained in acceptable limit.

Effect of storage period: Data depicts that storage of carrot candy resulted significant decrease in mean overall acceptability value (S) from initial overall acceptability value of 7.25 to 8.50 after six months of storage. The decrease in score of overall acceptability during storage could be correlated to change in colour, texture, taste and flavour of carrot candy. However, under room condition the quality was maintained to more than six months of storage.similar observations were recorded by Naik et al.

(2019) [17] , Raj et al. (2015) [26] for osmo-air dehydrated apricot, Nayak et ). The effects of H×S. H×P and P×S interactions were found significant, while H×P×S interaction was found non-significant effect.

Total Plate Count

The perusal of data pertaining to effect of sorbitol concentrations, packaging materials and storage on TPC of carrot candy has been presented in Table 10. Data depicts that storage of carrot candy resulted significant decrease in mean TPC value from initial TPC value of 0.00 to 2.52 after six months of storage. The TSS, moisture, total sugars and reducing sugars increased gradually during storage period while acidity, carotene and ascorbic acid decreased with increase in storage time. Microbial contamination was increased during storage period due to relative humidity and moisture content balance was disturbed, a suitable moisture environment created for microbial growth. The organoleptic characteristics such as colour, texture, taste, flavour and overall acceptability decreased slightly with advancement of storage period. Likewise, throughout the storage period, carrot candy was low microbial spoilage. Carrot candy prepared with coating of 10% sorbitol and packed in aluminium laminated packaging material (H 3 P 3 ) was found superior based on nutritional as well as sensory quality and found more shelf stable during storage compared to other treatments. The standard limit for consumption at acceptable level was observed up to 3.30 × 10 4 CFU/g. similar observation was reported by Naik et al. (2019) [17] for carrot candy.

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