INTRODUCTION:

Guava (Psidium guajava) is a delightful Myrtaceae fruit. Often known as the 'Apple of the Tropics,' Guava is a popular tree fruit in Asia.¹In Bangladesh, Guava is one of the favorite fruits of the people. It is a widespread and popular fruit in our country in production after mango. Some major Guava producing countries throughout the world are the USA, Brazil, Mexico, China, Cuba, Malaysia, India, Pakistan, Thailand, Peru, and Bangladesh.²The prevention of seasonal surplus fruit losses by processing and preservation techniques at the farmer and industrial levels should be encouraged. Such efforts will aid in the growth of processing industries in developing countries. Furthermore, this will drive increased output and provide guava growers with a higher return.²

In Bangladesh, Guava is mainly consumed as fresh fruit. Therefore, there is a broad prospect of producing guava products such as guava juice, pulp, Jelly, squash, marmalade, ready-to-serve beverages, candy, vinegar, wine, etc. But unfortunately, the present technology of production, processing, and Preservation of Guava in Bangladesh is not well developed up to its annual production volume. Therefore, it is essential to investigate to develop a suitable inexpensive method for processing and Preservation of Guava. There are several ways to process Guava. The sucrose used in Jelly becomes crystalline and evolved sugarflavor on storage. The present study was designed To analyze the effect of citric acid on prepared guava jelly. Also, observe chemical changes due to different citric acid concentrations during prepared Jelly storage during storage.

MATERIALS AND METHODS:

Materials:

The Guava (Psidium guajava) were obtained from the Chattogram local market. Sugar and citric acid were bought from a scientific and medical supply store. Other materials needed for the experiment were obtained from the laboratory's stock.

Formulation of guava jelly:

Guava jelly was prepared according to the preparation procedure described.⁴1kg fresh guava, 1.5kg water, and 0.75kg sugar were added during jelly preparation. Treatment is applied by using pectin and citric acid with three different percentages. The citric acid was applied at 1.1%, 1.15% and 1.2%, respectively, with fixed 0.2% pectin. Fresh Guava was weighed and washed thoroughly in cold water. The washed Guava was cut into thin slices with a stainless steel knife. Then it was boiled with one and half times the weight of fruit for about 30 minutes with stirring. Then 2g citric acid per kg of fruit was added during boiling. The boiled pieces were crushed and strained the extract through a thick cloth to remove the suspended matter consisting of fruit tissue, seed, skin, gums, and protein in colloidal form. The amount of guava juice, water, and sugar was calculated according to the formulation. The strained juice was boiled again, and sugar was added at a ratio of 1:1. Heating was continued with stirring. One teaspoon full edible oil was added per 45g of sugar to remove the scum of foam. 67-68oBx TSS indicated the endpoint in the mixture, which Refractometer measured. The Jelly was then filled in a glass jar. It was then covered with melted wax and cooled. After cooling, the cans or jars are labeled and stored for further studies.

Physicochemical analysis:

The moisture, total solids, ash, total soluble solids, pH, titratable AcidityAcidity, reducing sugar, nonreducing sugar, and total sugar content of fresh matured Guava, guava juice, and guava jelly were determined.⁵

Moisture content:

To determined moisture content. Five-gram fruit was taken in the crucible and placed in an oven at 105°C for 24hours until a constant weight was attained. Percent moister content was calculated using the following formula (i):

IW- FW

% Moisture content = ------------------- x100 …….. (i)

Total solids:

For determination of total solid. Percent total solid content was calculated by using the data obtained during moisture estimation using the following formula (ii):

%Total solids= 100 – % Moisture content. (ii)

Ash content:

Ash content was determined by the methods. Ash content is the inorganic residue remaining after the destruction of organic matter. Ten gram dried fruit was taken in a pre-dried weighed crucible. It was then burned to charcoal. The charcoal was then taken in a muffle furnace and heated at around 600°C for 4hours till the charcoal was removed entirely. The crucible is then taken out of the furnace. Cool it in a desiccator carefully and then weigh formula (iii).

W3- W1

% Ash content = ----------------- x 100 ………….. (iii)

W2 –W1

Titratable Acidity:

Titratable Acidity was determine by using initial 50-gram portion of the material was homogenized and then filtered, transported, and filled to the specified volume in a 250-ml volumetric flask using distilled water before being used in the study. Next, five milliliters of solution in a conical flask were titrated with 0.1N sodium hydro-oxide (NaOH) solution. Colorless to faint pink is seen at the end of the experiment and will last for 15 seconds. For accuracy, the titration was repeated numerous times.

Percent titratable AcidityAcidity was calculated using the following formula (iv):

T x N x V1x E

% Titratable Acidity = ----------------- x100 ……. (iv)

V2 x W

Total soluble solids (TSS):

The Abbe refractometer was used to determine the juice's total soluble solids. Refractometer prism with a drop of guava jelly in it to measure light scattering. The refractometer scale was used to determine the percent TSS.

Sugar:

The sugar content of fruit juice was determined by determining the volume of unknown sugar solution required to complete the reduction of Fehling's solution.

Fehling’s factor was calculated by using the following formula (v).

2.5 x Titre

Fehling’s Factor (g of inverts sugar) = ------- … (v)

1000

Percent reducing sugar was calculated according to the following formula (vi):

F x D x 100

% Reducing sugar = -------------------- ……… (vi)

Tx W

Estimation of non-reducing sugar

% Non-reducing sugar =

% total invert sugar- % reducing sugar ……. (vii)

Estimation of total sugar

% Total sugar =

% reducing sugar + % non-reducing sugar …….(viii)

The pH:

Using an electronic pH meter, we could get an accurate reading on the pH. Using a buffer solution of pH 4, the pH meter was first calibrated (standard buffer solution). Then, a beaker was used to collect the Jelly. Next, the pH meter electrode was submerged in the resolution for one minute, and the readings were taken. After each measurement, the pH meter's electrode was cleaned with distilled water.

RESULTS AND DISCUSSIONS:

Proximate composition:

Before preparing products, fresh Guava was tested and analyzed. The result of the proximate composition of guava fruit and product are tabulated in table 1.

Table 1: Physicochemical components of fresh guava

Parameters (per 100g)	Fresh Guava
Moisture (%)	82.5±2.09
Total Soluble Solid (^oBx)	15.5±1.07
Ash (%)	0.63±0.13
Acidity (%)	1.25±0.2
Reducing sugar	4.85±0.51
Nonreducing sugar	4.35±0.48
Total sugar	9.2±0.44

All data values in the table showed (ME±SD), where ME= Mean and SD= Standard Deviation. P3= 0.25% pectin treatment

Chemical analysis of guava jelly:

One way ANOVA (Analysis of variance) test was performed to see the overall mean difference of values for different parameters of guava jelly with citric acid treatment. Table 2 shows the laboratory test results of citric acid treatment in samples C1, C2, C3. It can be realized from the tables that Mean±SD values of moisture content, total soluble solids, acidity, pH, reducing sugar, nonreducing sugar, and natural sugar at different storage periods. The results showed a significant mean difference of values of various parameters on storage. Tukey's multiple comparison tests were performed to determine which days were the most important for this parameter. Tukey's Multiple Comparison Test (TMCT) at (p<0.05) was performed to show the significant pairwise difference of chemical parameters of jellies. It was observed from the above tables obtained from one-way ANOVA analysis that the moisture content of every sample increases with time duration. The highest moisture percentage was found in sample C1 (28.77±0.12^a), and the lowest rate was found in (25.56±0.25^a). A significant moisture change occurs in sample C1.The pH content of guava jelly decreased gradually with increased storage time at room temperature (25−30⁰C). On the other hand, acidity of guava jelly increased gradually with increased storage time. There was an inversely proportional situation found in this analysis between acidity and pH value. The pH value of Guava remained higher at room temperature as on the day of preparation. The lowest pH at the highest storage time supports the results. The higher acidity may be due to the further fermentation of alcohol produced from sugar fermentation and may be due to the addition of citric acid into the guava jelly.² The TSS of Jelly increased in the storage period. However, the difference of TSS was not statistically significant (P>0.01) in some samples. The variation was observed in reducing sugar and nonreducing sugar at storage conditions. A remarkable increase in reducing and nonreducing sugar was observed after the 90th day of storage. This might be due to the fermentation of added sugar into alcohol and carbon dioxide during the storage period.²

The guava is not only delicious fruit across the world but also used in various extracts form and providing beneficial effects against metabolic illiness. In this study, we discuss the guava jelly preparation and preservation. Various artificial preservation used in food products which not only harmful but also change the physicochemical characteristic of product. Tn this study we used citric acid in preparation as well as preservation of guava jelly at room temperature. Citric acid applications well studied widely in various field. Here, we use as a key acid for preservation of guava jelly. The Physicochemical analysis is effective technique use to analyse the effect of various factors.^6-15 In previous study the physicochemical analysis of guava performed which shows that it contains 0.4% pectin, 4.5% reducing sugar, 3.5% nonreducing sugar, 8.9% total sugar, 80.61% moisture, 0.7% total ash, 1.28% acidity, and 19% TSS.¹⁶ Similar results was visible in our study, which includes: 82.5% moisture, 15.5% TSS, 0.63% ash, 1.25% acidity, 4.85% reducing sugar, 4.35% non-reducing sugar, and 9.2% total sugar in fresh Guava. A little difference may be due to instrumental error or inefficient measurement. In this study, soil nutrients and composition of the growing area and inefficient measurement or instrumental error have influenced varietal differences. It is noted here that the variety of guava cultivars used in this experiment is unknown. The higher amount of sugar in prepared Jelly is due to extra sugar in the formulation. It was clear that the moisture content (%) of samples increased with an increase in storage periods at room temperature (25−30^oC). Approximately 2% moisture increased in 120 days of storage. The combined effect of composition and storage period were found significant. The study also revealed that moisture content (%) increased with an increase in storage period at ambient storage. Aggarwal et al. (1997) reported a similar propensity for grape blends jelly during storage.¹⁷The increase of moisture content is due to the hydrolysis of sugar into alcohol, carbon dioxide, and water during storage (Paul et al., 2007).¹⁸The TSS of samples increased with an increase in storage periods at room temperature (25−30^oC). It is explicit that the effect of different compositions and storage periods was found significant. The highest increase of TSS (68.36% to 69.39%) was found in sample C3 (citric acid 1.2%). The combined effect of composition and storage period were also significant. The study also revealed that TSS increased with an increase in storage period at room temperature (25−30^oC), which was similar to previous reported study.¹⁹ Also, reported that the significant increase (P< 0.05) in TSS could be due to the degradation of polysaccharides during storage into soluble compounds.²⁰

Insufficient acid is one of the most prevalent causes of jelly failure. The pH value should be measured when the Jelly is sufficiently concentrated to pour. Add citric acid if the pH is more significant than 3.3 to bring the pH from 3.0 to 3.2.²¹ It is better to add citric acid in the boiling process. It allows for greater control of the pH and minimizes pre-gelling and hydrolysis of the pectin, which are both undesirable. Depending on the natural acidity of the juice and the juice's buffering capacity, different juices will require additional quantities of added acid. It is possible to adjust the pH to achieve the best flavor, to control or alter the rate of setting, and to alter the quantity of sugar inversion, among other things.

A higher percentage of citric acid showed lower higher acidity. The lowest acidity (0.112%) and highest pH value (3.2) were found in guava jelly with 11% citric acid. This propensity is similar to the previous studies performed.²²This analysis observed variation in reducing sugar and nonreducing sugar at storage conditions. A remarkable increase in reducing sugar was observed after the 90th day of storage. The percentage of reducing sugar increased more than nonreducing sugar. The increase in reducing sugar might be due to the hydrolysis of sucrose. Nonreducing sugar didn't increase or decrease insignificant amounts; in some cases, it decreased. A similar propensity was found by Babsky et al. (1986) and Pruthi et al. (1984)^23-24 that nonreducing sugars of drinks are converted into reducing sugar during storage. The overall percentage of nonreducing sugar was similar for both treatments. Total sugar increased slowly during 90 days storage period in response to reducing sugar.

Table 2: Physicochemical constituents of guava jelly with citric acid treatment during storage (at 25-30^oC)

Sample	C1 (citric acid 1.1%)
Parameters	Storage time in days
Parameters	1	30	60	90	120	F-test
Moisture Content %	26.63 ±.057^a	27.47 ±.08^ab	28.1 ±0.0^bc	28.24 ±0.08^c	28.55 ±.08^c	18.42**
Total Soluble Solid (^oBx)	67.03 ±0.57^a	67.3 ±0.00^a	67.19 ±0.05^a	67.17 ±0.06^a	67.17 ±0.06^a	1.11^NS
Acidity %	0.112 ±.034^a	0.141 ±0.09^a	0.181 ±0.023^ab	0.211 ±0.02^ab	0.238 ±0.023^b	6.08*
pH	3.2 ±0.06^a	3.12 ±.05^ab	2.96 ±.07^ab	2.89 ±0.0^ab	2.83 ±.12^b	3.97*
Reducing Sugar %	31.16 ±0.57^a	31.3 ±.34^ab	32.67 ±.92^bc	32.1± .05^abc	33.22 ±0.03^c	8.87**
Nonreducing Sugar %	8.53 ±0.28^a	8.55 ± 0.15^a	8.47 ±0.17^a	8.44 ±0.17^a	8.39 ±0.06^a	3.48^NS
Total Sugar %	39.5 ±0.86^a	39.8 ±.49^ab	41.3± 1.02^bc	40.7± .23^abc	38.55 ±.081^c	8.08**

Table 2 Cont..1…: Physicochemical constituents of guava jelly with citric acid treatment during storage (at 25-30^oC)

Sample	C2 (citric acid 1.15%)
Parameters	Storage time in days
Parameters	1	30	60	90	120	F-test
Moisture Content %	28.17 ±0.12^a	28.47 ±0.03^ab	28.65 ±0.04^ab	28.73 ±0.17^b	28.77 ±0.12^b	8.13**
Total Soluble Solid (^oBx)	67.0 ±0.05^a	67.22 ±0.10^a	67.35 ±011^b	67.53 ±0.12^b	67.93 ±0.12^b	24.91**
Acidity %	0.191 ±0.04^a	0.196 ±0.04^a	0.25 ±.005^ab	0.31 ±0.017^bc	0.35 ±0.02^c	20.71**
pH	2.88 ±0.03^a	2.83 ±.017^a	2.75 ±.01^b	2.68 ±0.02^c	2.66 ±0.02^c	45.88*
Reducing Sugar %	31.13 ±0.15^a	31.13 ±0.12^a	31.20 ±.17^ab	31.40 ±.19^b	31.61 ±.17^b	66.51**
Nonreducing Sugar %	8.53 ±0.12^a	8.45 ±0.15^a	8.6 ±0.17^a	8.567 ±0.40^a	8.51 ±0.40^a	0.03^NS
Total Sugar %	39.6 ±0.17^a	39.67 ±0.26^a	39.76 ±0.32^a	40.17 ±0.57^a	40.11 ±.34^b	11.5**

Table 2 Cont…2..: Physicochemical constituents of guava jelly with citric acid treatment during storage (at 25-30^oC)

Sample	C3 (citric acid 1.2%)
Parameters	Storage time in days
Parameters	1	30	60	90	120	F-test
Moisture Content %	1	30	60	90	120	F-test
Total Soluble Solid (^oBx)	26.35 ±0.15^a	26.43 ±0.12^ab	26.56 ±0.06^abc	26.62 ±.03^bc	26.75 ±0.09^c	9.16**
Acidity %	68.36 ±0.06^c	68.66 ±0.06^bc	68.83 ±0.12^b	69.39 ±0.05^a	69.39 ±0.05^a	47.067 **
pH	0.283 ±0.01^a	0.303 ±0.01^ab	0.346 ±0.023^b	0.366 ±0.02^b	0.366 ±0.02^b	25.473**
Reducing Sugar %	2.73 ±0.03^a	2.64 ±.046^a	2.53 ±.02^ab	2.46 ±.04^bc	2.33 ±.04^bc	13.40**
Nonreducing Sugar %	30.33 ±0.11^a	30.33 ±.461^a	30.83 ±.11^ab	31.16 ±.18^b	31.36 ±.17^b	36.98**
Total Sugar %	8.87 ±0.12^a	8.88 ±0.11^a	8.86 ±0.01^a	8.92 ±0.05^a	8.926 ±0.047^a	1.521^NS

All values in the table showed (ME±SD) of data, where ME= Mean and SD= Standard Deviation, superscripts a,b, c denotes significant difference (P<0.05) between samples, NS= Not Significant, *= significant (P<0.05), **= effective (P<0.01).

CONCLUSIONS:

The objectives of the present study were to observe the effect of citric acid on preparation and changes in qualities of guava jelly without preservatives for storage. Acidity and pH of 1.1% and 1.2% citric acid was differed significantly after preparation. Additional citric acid was compensated in jelly processing. This study claims quality properties do not vary due to citric acid among three formulations of Jelly. Therefore this formulation could be practiced for escalating the country’s developing food industries.

ACKNOWLEDGEMENTS:

The authors would like to acknowledge the Department of Applied Food Science and Nutrition and Department of Food Processing and Engineering, Faculty of Food Science and Technology and Poultry Research and Training Center (PRTC), Chattogram Veterinary and Animal Sciences University, Chattogram, Bangladesh, for research support facilities and Universiti Terengganu Malaysia for TAPERING/2021/UMT/807 grant provided to Dr. Gul-e-Saba Chaudhry.

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Received on 24.03.2022 Modified on 12.01.2023

Research J. Pharm. and Tech 2024; 17(2):512-516.

DOI: 10.52711/0974-360X.2024.00080