Influence of granular sugar and sugar syrup on physicochemical quality of rose gulkand

Introduction

Rose is an economically important flower crop with considerable potential for value addition through products such as rose water, rose oil, syrup and gulkand. It belongs to the family Rosaceae and has wide applications in the food, medicinal and cosmetic industries. The petals of Rosa centifolia contain bioactive constituents and are used in the preparation of various value-added products, including gulkand (Mabellini et al., 2011; Nadaf et al., 2012) [7, 8] . Gulkand is a traditional rose-petal preserve prepared by combining fresh petals with sugar and is valued for its pleasant flavour, nutritional attributes and traditional uses. It also provides an effective means of utilizing perishable rose flowers and reducing post-harvest losses (Kumar et al., 2017; Shukla et al., 2024) [6,12] . The quality and storage stability of gulkand are influenced by the amount and form of sugar used during preparation. Changes in physicochemical constituents such as moisture and sugars have been reported in gulkand during processing and storage (Bors et al., 2014) [4] . Therefore, the present investigation was undertaken to evaluate the effect of different levels and forms of sugar on the physicochemical quality of gulkand prepared from Rosa centifolia during storage and to identify a suitable sugar combination for its preparation.

Materials and Methods

The present investigation entitled "Studies on Preparation of Gulkand from Rose" was carried out at the Department of Floriculture and Landscaping, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola during 2025-2026. Fresh flowers of Rosa centifolia were procured from the field. The flowers were cleaned and unwanted floral parts were removed, followed by washing and shade drying of the petals. The experiment was laid out in Completely Randomized Design (CRD) with ten treatments and three replications. For each treatment, 1 kg rose petals were used. Treatments T₁ to T₅ comprised 1kg of rose petals and granular sugar of 800g, 900g, 1000g, 1100g and 1200g, respectively, whereas T₆ to T₁₀ comprised 1 kg of rose petals and sugar syrup treatments with 80%, 90%, 100%, 110% and 120% sugar, respectively. Sugar syrup was prepared at 75 °Brix. The respective quantities of petals and sugar and sugar syrup were filled in sterilized glass jars, sealed and labelled. The jars were exposed to sunlight at 30-35 °C and stirred on alternate days to facilitate uniform impregnation. Observations were recorded at initial, 30 th , 60 th , 90 th , 120 th and 150 th day of storage. The gulkand samples were evaluated for pH, TSS, moisture content, total sugars and reducing sugars using standard analytical procedures. The pH was measured using a Perkin Elmer pH meter, while TSS was determined using a digital refractometer and expressed in °Brix (AOAC, 1995) [2] . Moisture content was determined using the hot air oven method following AOAC (2005) [1] . About 10 g of gulkand sample was dried at 105 ± 2°C until a constant weight was obtained, and the moisture content was expressed as per cent. Reducing sugar content was estimated by the 3,5-dinitrosalicylic acid (DNS) method described by Sadasivam and Manickam (1997) [10] , with absorbance measured at 540 nm using a spectrophotometer. Total sugar content was determined by the phenol-sulphuric acid method of Sadasivam and Manickam (1997) [10] , and absorbance was recorded at 490 nm. The results for both reducing and total sugars were expressed as per cent. The data was statistically analysed using Completely Randomized Design (CRD) and the significance of treatment differences was tested at the 5% level of significance.

Result and Discussion

pH

The data pertaining to pH of gulkand under different treatments during storage revealed a gradual decline with the advancement of storage period. At initial day of storage, the highest pH (5.20) was recorded in treatment T₅, whereas the lowest pH (4.91) was observed in treatment T₆. The differences among the treatments were found to be nonsignificant at the initial stage. From 30 th day onwards, significant differences were observed among the treatments.

Treatment T₅ maintained a comparatively higher pH throughout the storage period, with a decrease from 5.18 at 30 days to 5.04 at 150 th day. In contrast, treatment T₆ recorded the lowest pH, declining from 4.79 to 3.95 during the corresponding storage period. Tamrakar et al. (2020) [13] reported a similar decline in pH during the storage of gulkand, which is similar to the trend observed in the present investigation. The reduction in pH during storage might be attributed to the formation and accumulation of organic acids along with progressive biochemical changes occurring in the product. Sarfarazi et al. (2024) [11] also observed a comparable decrease in pH of gulkand during storage. [3] also reported significant variation in TSS among different rose gulkand formulations prepared using natural sweeteners, supporting the influence of formulation on soluble solids. The increase in TSS during storage may be attributed to the concentration of soluble constituents and progressive biochemical changes occurring in the product. Jat et al. (2022) [5] observed an increase in TSS during storage of rose petal jam, which is in agreement with the present findings.

A gradual reduction in the moisture content of gulkand was observed as the storage period progressed. At the beginning of storage, treatment T₆ recorded the highest moisture content (82.98%), while the lowest value (78.98%) was noted in treatment T₅. The treatments differed significantly at all storage intervals. In treatment T₆, moisture content decreased from 82.98% at initial day to 51.03% at 150 th day, whereas treatment T₅ showed a more pronounced decline from 78.98% to 41.96% over the same period. This reduction might be associated with the gradual loss of water from the product due to the moisture gradient between gulkand and the surrounding atmosphere, further influenced by the osmotic action of the concentrated sugar. The relatively lower moisture content in treatment T₅ has led to better storage stability by limiting the availability of water required for microbial growth and other moisture dependent deteriorative changes. Venkateshan et al. (2023) [14] reported a gradual reduction in moisture content during storage, corroborating the trend observed in the present study. Similarly, Ochelle et al. (2024) [9] documented a decline in moisture content during storage of jam, further supporting the present observations.

The total sugar content of gulkand showed a steady increase with the advancement of storage period. At initial day of storage, treatment T₅ recorded the highest total sugar content (63.04%), whereas the lowest value (53.02%) was observed in treatment T₆. The differences among the treatments were significant at all storage intervals. Treatment T₅ retained the highest total sugar content throughout storage, increasing from 63.04% at initial day to 66.23% at 150ᵗʰ day, while treatment T₆ exhibited a comparatively smaller increase from 53.02% to 55.47% during the same period. The rise in total sugar content may be attributed to the hydrolysis of complex carbohydrates into simpler sugars, along with the concentration of soluble constituents resulting from moisture loss during storage. Tamrakar et al. (2020) [13] reported an increase in total sugar content of gulkand during storage, which corroborates the trend observed in the present study. Sarfarazi et al. (2024) [11] also documented a progressive increase in total sugar content during storage, further supporting the present findings.

The reducing sugar content of gulkand exhibited a steady increase with the advancement of storage period. At initial day of storage, the highest reducing sugar content (3.65%) was recorded in treatment T₁₀, while the lowest (3.04%) was observed in treatment T₁. The differences among the treatments were significant at all storage intervals. A progressive rise in reducing sugar content was observed in all treatments during storage, with treatment T₁₀ increasing from 3.65% at initial day to 12.92% at 150ᵗʰ day, whereas treatment T₁ increased from 3.04% to 10.34% over the same period. This increase may be associated with the inversion and hydrolysis of sucrose into simpler reducing sugars, predominantly glucose and fructose, along with the breakdown of complex carbohydrates during storage. Tamrakar et al. (2020) [13] observed a progressive increase in reducing sugar content during storage of gulkand, which is in accordance with the present findings. Sarfarazi et al.

(2024) [11] also reported an increasing trend in reducing sugars during storage, further corroborating the results of the present investigation.

Conclusion

The present investigation revealed that the physicochemical quality of rose gulkand was influenced by the form and level of sugar used during preparation. As storage progressed, pH and moisture content gradually decreased, while total soluble solids, total sugars and reducing sugars showed a steady increase. Among the treatments, rose petals + granular sugar (1:1.20) exhibited the most favourable overall physicochemical characteristics, with higher TSS and total sugar content, lower moisture content and comparatively better retention of pH during storage. The overall response of treatment rose petals + granular sugar (1:1.20) indicates a favourable balance of quality attributes and storage stability. Therefore, treatment rose petals + granular sugar (1:1.20) can be considered the most promising formulation for the preparation of rose gulkand under the conditions of the present investigation.

Acknowledgement

I sincerely express my gratitude to my research guide, Dr. Manisha S. Deshmukh, and my Advisory Committee members for their valuable guidance, encouragement and support throughout the investigation.

References

1. Association of Official Analytical Chemists International. Official methods of analysis. 18th ed. Gaithersburg, MD: Association of Official Analytical Chemists International; 2005.
2. Association of Official Analytical Chemists. Official methods of analysis. 16th ed. Washington, DC: Association of Official Analytical Chemists; 1995. p. 37.
3. Ajai T, Prasanth P, Lakshminarayana D, Praneeth Kumar S. Standardization of recipe for rose gulkand by using natural source of sweeteners. Pharm Innov J. 2022;11(11):2257-2262.
4. Bors MD, Petrut GS, Tofana M, Socaci S, Farcaș A. Study regarding the production and characterization of rose petal jam enriched with Saint John's wort (Hypericum perforatum) essential oil. Bull UASVM Food Sci Technol. 2014;71(1):70-77.
5. Jat R, Mahawer LN, Bairwa HL, Pilania S, Tak JK, Singh H. Impact of sugar, sugar candy, jaggery and honey levels on physicochemical changes of Bourbon rose petal jam at ambient storage. Int J Plant Soil Sci. 2022;34(10):27-36.
6. Kumar A, Kaur A, Joshi VK, Kumar V. Rosa damascena: quality evaluation and process optimization for the development of rose syrup. Int J Food Ferment Technol. 2017;7(2):279-285.
7. Mabellini A, Ohaco E, Ochoa MR, Kesseler AG, Márquez CA, De Michelis A. Chemical and physical characteristics of several wild rose species used as food or food ingredient. Int J Ind Chem. 2011;2(3):158-171.
8. Nadaf NY, Patil RS, Zanzurne CH. Effect of addition of gulkand and rose petal powder on chemical composition and organoleptic properties of shrikhand. Recent Res Sci Technol. 2012;4(10):52-55.
9. Ochelle PO, Torkuma ST, Swande PI. Quality evaluation of jam produced from fresh and dried roselle calyces (Hibiscus sabdariffa). Appl Sci Res Period. 2024;2(1):74-95.
10. Sadasivam S, Manickam A. Vitamins. In: Sadasivam S, Manickam A, editors. Biochemical methods. 2nd ed. New Delhi: New Age International; 1997. p. 185-186.
11. Sarfarazi S, Mahawer LN, Bairwa HL, Pilania S, Meena RH, Upadhayay B. Development of physicochemical standards for Gulkand as influenced by varying levels of sugar and sugar candy. J Hortic Sci. 2024;19(2).
12. Shukla RK, Singh P, Kumar V, Verma RP, Chakravarty A, Srivastava RK. Importance and nutritional value with therapeutic properties of a traditional gulkand: A review. J Med Aromat Plant Sci. 2024;46(2):43-50.
13. Tamrakar P, Sahu TL, Parihar N. Standardization of recipe for gulkand and evaluation of its physicochemical characteristics during storage. Pharma Innov J. 2020;9(12):373-377.
14. Venkateshan P, Prasad VM, Singh A. Effect of sugar concentration and value addition on physico-chemical of bael candy (Aegle marmelos Correa) cv. NB-9. Int J Plant Soil Sci. 2023;35(18):1379-1385.