Effect of size of Osmo-dehydrated carrot shreds on quality of Redimix of Gajarhalva

Introduction

Carrot (Daucus carota L.) is a major nutrient-dense root vegetable having significant nutritional characteristics. Orange carrots have potent antioxidants due to wide distribution of carotenoids. It exerts anti-carcinogens, anti-diabetic, anti-hypertensive, cholesterol lowering activities and modulates immune response in human body (Mondhe et al. 2017; Silva, 2014) [1, 2] . Due to loaded nutritional benefits and a valuable source of natural antioxidants, the consumption of carrots and their products is steadily increasing (Sharma et al. 2012) [3] . Apart from being rich in bioactive compounds such as carotenoids and dietary fibres, carrots contains a high percentage of moisture, ranging from 86 to 89%. This high moisture is a major hurdle for shelf life of fresh carrots. The different processing techniques helps to increase its shelf life and make the carrot products available throughout the year for people. Gajarhalva is one of the most delicious and popular carrot desserts in Indian food. In the traditional method, the process of gajarhalva is tedious and time consuming. But in the last few years, there has been a drastic change in food habits and cooking methods due to urbanization and social modification. People are always in a need of quick, convenient and low time consuming food preparation methods because of busy life style. Ready to cook (RTC) products are the type of foods which are processed or prepared with very little extra efforts. This type of food is becoming popular because of its convenient, time and labour saving nature. The market for RTC/RTE food products in India stood at 261million in 2017 and projected to rich at 647 million (Temgire, et al. 2021) [4] . The ingredients which are commonly used in traditional method of gajarhalva are carrot shreds, milk or milk powder and ghee. Coconut meal and dry fruits are sometimes used to increase its nutritional as well as sensory value. Vaidya Pallavi (2024) [5] formulated the ready to cook Redimix of gajarhalva and optimized the levels of orange carrot shreds, coconut meal and skim milk powder using Response Surface Methodology. But it was observed that the size of shreds influences the cooking time and overall acceptance of gajarhalva. Generally pink carrots are available in particular period of year but there is year round availability of orange carrots. Hence the experiments were planned to assess the effect of size of shreds on overall acceptability of Redimix of gajarhalva prepared from orange carrot. Trials were also carried out to determine the selected quality parameter of Redimix of gajarhalva at ambient storage condition.

Materials and Methods

Sample preparation

Fresh and firm carrots were purchased from local market. Well matured and uniform sized carrots were peeled and trimmed to remove undesirable top and bottom portion. Peeled carrots were thoroughly washed with water and grated by using a different vegetable grater to prepare the carrot shreds of three sizes as per treatments. Carrot shreds were steam blanched up to for 2 minutes time duration and osmo-convectively dehydrated up to 5% (w b.) moisture content for preparation of Redimix (Malik et [6,7,8,9] . Redimix was formulated by incorporating coconut meal and milk powder in osmo-convectively dehydrated orange carrot shreds of different sizes in the proportion of 67:10:27 in 100 g (Vaidya Pallavi, 2024) [5] . Redimix of gajarhalva with highest overall acceptance was used for storage study. Redimix was packed in aluminium laminated foil (P 1) and PET pouches (P 2) and stored at ambient temperature condition (25 ± °C; 65 ± 4% RH) for 90 days. All stored samples were evaluated for water activity, colour, texture, free fatty acid (FFA) and overall acceptability during storage.

Quality Evaluation

Redimix prepared from orange carrot shreds of different sizes was evaluated for WAI. Other parameters such as the colour, texture and overall acceptability were evaluated in cooked/ready to serve form of gajarhalva. Water Absorption Index (WAI) was determined according to (Nguyen et al. 2015) [10] . Ready to serve form of gajarhalva was prepared by cooking Redimix in boiling water with 2:1 ratio of water to Redimix. Cooking was carried out about 5 ± 2 min to get required consistency of cooked gajarhalva. Consistency of ready to serve form of halva was observed visually. Before serving, it was fortified with ghee and dry fruits for increasing its overall acceptance. The colour of ready to serve gajarhalva was measured in terms of L * , a * , b * value using a Hunter lab Colour Analyzer, Inc. Virginia, USA (Rahman et al. 2002) [11] . Texture is one of main quality parameters related to the rheological and structural properties of food. Textural parameter of cooked gajarhalva was measured in terms of consistency a using a Texture Analyzer (Model: TA-XT plus, Stable Micro System, UK). Texture in terms of consistency was determined by using P/75 probe (Bourne, 1978) [12] . Water activity of stored sample was measured by using Aqua Lab Water Activity Meter. Standard method of AOAC (2005) [13] was used to determine free fatty acid in stored Redimix. Sensory score indirectly signifies the shelf-life and stability of food products which in turn refers to consumer acceptability. Lighting or darkening of colour, loss of flavour, taste and texture are the major changes that take place in dried food products during storage. Overall acceptability of Redmix of gajarhalva was considered as average score obtained for various quality attributes like colour, appearance, flavour, texture, and taste of cooked form of halva. Microbial food safety is an essential component of food quality and hence stored samples were evaluated for total plate count by using standard procedure (ISI, 1969) at regular interval of 30 days. Sensory parameters were evaluated with the help of a semi-trained panel using a 9-point Hedonic scale by standard method (ISI) (1971a-1971b).

Results and Discussion

Effect of size of carrot shreds on quality of Redimix of gajarhalva

The carrot shreds of different size were prepared and osmoconvectively dehydrated for the formulation of Redimix. The size of shreds was measured before osmo-convective dehydration and presented in Table 1. The length varied from to be 15.75 to 29.37 mm whereas the width varied from 2.90 to 4.47 mm for S 1 , S 2 and S 3 samples respectively. Water absorption index is a capacity to absorb water and swell providing desirable consistency. Water absorption index of Redimix varied from 2.00 to 2.42 within the treatments. A linear correlation was also observed in WAI with increasing size of carrot shreds. S 3 treatment formed granules in the solution and absorbed more amount of water than S 1 (Small) and S 2 (Medium) shreds. Texture was measured in terms of consistency of Ready to serve form of Redimix. The values of consistency decreased from 23.67 to 19.21 N with increase in size of shreds. It was also observed that Ready to serve form of halva prepared from smaller size shreds showed more stickiness while large shred exhibited less stickiness. It might be due to lower sugar gain obtained by the carrot shreds of large size than smaller one during the process of osmosis (Manisha et. al, 2025) [6] . Higher sugar gain resulted in more stickiness of cooked Redimix during cooking. Overall acceptability is one of the major factors that influence the product acceptance by its multi-dimensional nature. Overall acceptability was determined by considering the score for appearance, colour, taste and aroma/flavour of cooked gajarhalva. Fig. 3 showed that gajarhalva prepared from medium size carrot shreds (GS 2 ) exhibited higher score for appearance, taste and aroma/flavour than other two treatments. It might be due to higher consistency of cooked form of gajarhalva and considerable sugar gain obtained by medium sized carrot shreds during the process of osmotic dehydration. Overall acceptance of gajarhalva prepared from medium size carrot shreds was highest among the other two treatments.

Quality assessment of Redimix of gajarhalva during ambient storage condition Fig. 4 illustrates the changes in water activity of Redimix of gajarhalva stored in aluminium laminated foil and PET pouch at ambient condition for three months. Although samples packed in both packaging showed an incremental changes in water activity, but the increase was higher in PET pouches than aluminium laminated foil. Increase in water activity of stored samples resulted from the moisture gain by the sample during storage. Changes in water activity were negligible up to 45 days of storage. Overall higher changes were observed for PET packaging as compared to ALF. Similar higher changes in water activity were observed by Loo and Pui (2020) [14] for kuini powder stored in polyethylene terephthalate than aluminium laminated polyethylene. However noted values of the water activity for both the packaging material are far below than the critical limits (Mithila et al. 2020; Farminin and Nordin, 2009) [15,16] . Redimix. However non-significant difference was noticed for both the samples during ambient storage of three months. (2019) [17] was also observed a similar increasing trend in FFA values of instant rice porridge mix formulated by using skim milk powder during storage. The change in these values was very small or negligible up to 45 days of storage. After 45 days, sample stored in PET material exhibited higher values than the sample stored in ALF. Increase in water activity of stored sample led to increase in FFA values during storage. Moisture was an important factor affecting shelf life as it triggers other quality parameters such as FFA, water activity and microbial load (Mithila et al. 2020) [15] . Total plate count is most commonly used to evaluate microbiological quality of a food. Osmo-convectively dehydrated fruits and vegetable products generally have very low moisture content and water activity. Therefore, change in total plate count of stored samples was examined at an interval of 30 days and data is presented in Fig. 8. Total plate count of samples was increased slightly up to 115×10 2 cfu/g at the end of 90 days of storage period. Overall gradual increase in total plate count was observed with increased storage period. However, observed values of TPC of Redimix stored in both packaging material were far below the critical level of 1 x 10 5 cfu/g during the storage period of three months (Mithila et al. 2020; FAO, 2001) [15,18] Redimix packed in aluminium laminated foil obtained higher overall acceptance than the sample packed in PET pouch at the end of storage period of three months.

Conclusion

Considering the FFA and overall acceptability, Redimix of Gajarhalva stored in Aluminium laminated foil and PET pouches at ambient conditions were acceptable during storage period of three months. Aluminium laminated foil indicated very less increase in FFA and water activity values as compared to PET pouches.

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