INTRODUCTION:

Fruits are seasonal and have a short shelf life, necessitating preservation and other heat treatments during processing to maintain quality and provide various products like pulp, jam, jellies, and juices better preservation throughout the year, particularly in the off-season. Many preserved fruit species have great economical-agricultural potential and are traditionally used by the locals. There are various ways to enjoy fruits, such as juice, ice cream, jams/jellies, and other sweets.^1-2 These ingredients contribute to a pleasant taste and an abundance of nutrients such as sugars and proteins, as well as B vitamins and carotenoids.³

To avoid postharvest fruit loss and provide a unique product to consumers, jam and jelly are made with various additives (such as sugar, acids, or sweeteners, and a thermal approaches. However, otherside, fruits that are contaminated with microorganisms trigger the risk of infectious disease.^4-5Contaminants such as Escherichia coli and Salmonella spp. can be harmful to human health. Other common contaminants include Listeria monocytogenes, Aeromonas spp., Staphylococcus spp., Streptococcus species, Vibrio species, and Pseudomonas.^6-8 There is a risk that bacteria and fungi can spread through fruit and preservative products if left untreated.⁹ The spread of these microorganisms and fungi can be prevented by employing various preservation procedures. As there are many fruits and certain vegetables that can be used to make jams, jellies, and marmalade and store in Preserves form. A healthy diet can include a wide variety of fruits rich in vitamins and minerals and a considerable deal of flavor. Moreover, a key characteristic of preserves is their strong acidity, which helps preserve the color and flavor of most fruits while also preventing the growth of food poisoning bacteria. However, some molds and yeasts can develop at high acidity levels. In order to keep them from ruining jams and jellies, a sugar concentration of 68% necessary. The fungus or Molds will begin to grow on the product's surface if its sugar level is lower than this threshold. By keeping thesekey aspects, jam and jelly preservation must be developed to produce a high-quality final product that can be stored for an extended period without going bad.Interestingly along with delicious taste, and potential compounds, guava fruits used to treat metabolic disorders. However, many of the artificial preservatives use in preservation which can cause detrimental effects on human health. The citric acid and pectinhave been used in various applications yet to be explored in jelly preparation and preservation. Pectin is an essential food ingredient and source of dietary fiber that has been extensively researched.^10-19 In Bangladesh, guava is mainly consumed as fresh fruit. There is a wide prospect of producing guava products such as guava juice, pulp, jelly, squash, marmalade, ready-to-serve beverage, 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 methods for processing guava. The sucrose used in jelly becomes crystalline and evolves sugar flavor on storage. The present study was designed to fulfill the following objectives:The primary objectives of this study were as follows; To test the microbial quality of the developed jelly during storage at room temperature.To assess the overall acceptability of the designed products and their storage life.

MATERIALS AND METHODS:

Methods:

Formulation of guava jelly:

The experimental raw materials guava (Psidium guajava) was collected from the local market of Chattogram. Guava jelly was prepared according to the preparation procedure described.⁹

Microbiological analysis:

Sample preparation:

The 25g of this mixed guava jelly was taken in a 250ml flask. Phosphate buffer saline (0.6mM KH₂PO₄ of pH 7.2) was used to dilute the sample. About 100ml of the buffered saline was added to the beaker and mixed well by to-and-fro movement. The volume was made up of the same buffer water. All the apparatus, solutions, and other tools should be sterilized, i.e., heated at 121⁰C for 15 minutes. The prepared sample was then diluted to 10 times, i.e., 1×10^-1 time’s dilution, and used as stock solution.²⁰

Standard plate counts:

An SPC was used to estimate the level of microbes in the prepared and stored guava jellies. This data could be used as food quality indicators or predictors for the product's shelf life. The 1 ml of the diluted sample was then taken into each of the sterile empty Petri-dishes having nutrient agar media (Plate count agar) at a temperature of 45°C. Plates were mixed by swirling on a flat surface. After solidifying the media, the plates were inverted and incubated at 37°C for 24 hours in an incubator.²¹

Counting and recording:

After incubation, the incubated plates were selected to count the bacterial colony based on the number and easy counting of the colony. The plate containing segregated, overlapping, and confusing colonies was avoided. The plates containing 30 to 250 bright, cleared, and countable colonies were selected via formula (i) below.

Number of colony forming unit (cfu)/g or ml.=

Average cfu

--------------x dilution factor (i)

plate

The viable bacterial count was done through sample preparation, sample dilution, standard plate counts, and counting and recording. The incubation was performed at 37°C for 24 hours.

Fungal analysis in jelly:

Media Preparation

For the isolation of dermatophytes and other fungi and yeasts, Sabouraud Dextrose Agar (SDA) is the most commonly used selective medium. However, it can also be used to grow filamentous bacteria such as Nocardia. While bacteria are inhibited by the acidic pH of this medium (pH around 5.0), most filamentous fungi can thrive in this environment. Additionally, antibacterial agents can be used to boost the antibacterial effect further. Yeasts and moulds thrive in SDA media because it's rich in amino acids and nitrogenous compounds from casein and animal tissues, which are digested by enzymes. SDA media is made up of 10g Mycological peptone (enzymatic digest of casein and animal tissues), 40g Dextrose, and 15 g Agar with pH 5.6 at 25 ⁰C. All media were sterilised in an autoclave at 121°C for 15 minutes after being prepared according to the manufacturer's instructions. Mold and yeast cultures can be grown and identified using a variety of selective agars, but few of these rely on specific nutritional requirements for growth. Sabouraud Dextrose Agar is ideal for the cultivation of a wide variety of fungi. Methods and techniques are used as described in this article.^22-24

Table 1: Microbiological quality of guava jelly

Samples	Total viable bacteria (CFU/ml)					Yeast and Mold
	Storage time in days					Storage time in days
	1	30	60	90	120	1	30	60	90	120
P1 (pectin 0.15%)	ND	1.2×10	1.7×10²	2.8×10³	2.9×10⁵	A	A	A	A	P
P2 (pectin 0.2%)	ND	1.2×10	1.6×10²	2.6×10³	2.7×10⁵	A	A	A	A	P
P3 (pectin 0.25%)	ND	1.1×10	1.5×10²	2.7×10³	2.4×10⁵	A	A	A	A	P
C1 (citric acid 1.1%)	ND	1.3×10	1.4×10²	2.1×10³	2.2×10⁵	A	A	A	A	P
C2 (citric acid 1.15%)	ND	1.1×10	1.3×10²	2.0×10³	1.9×10⁵	A	A	A	A	P
C3 (citric acid 1.2%)	ND	1.1×10	1.2×10²	1.8×10³	1.7×10⁵	A	A	A	A	P

Legends:ND= Not Detected, A= Absent, P= Present

Interpretation:

After appropriate incubation, the plates should exhibit solitary colonies in streaked areas and confluent growth in heavily inoculated areas. Inspect plates for fungal colonies with characteristic colour and form. Additional procedures should be carried out to verify the results. Yeasts form colonies that range in colour from creamy to white. Molds form filamentous colonies in a variety of colours.²⁵

Techno-economic feasibility of guava jelly:

Model III of Inventory Theory is used, which states that there are no shortages in an economic lot size model with a uniform rate of finite demand for supply (Including the basic theory of Inventory Theory). Guava jelly can only be prepared if all of the presumptions are met. On the basis of actual experience, we made the assumption that the startup costs would be as low as possible.²⁶

Statistical analysis:

IBM SPSS Statistics 25 was used for the statistical analysis. One-way ANOVA techniques were used to assess a significant amount of variance at a 95% confidence interval for the proximate composition and sensory evaluation data. To further investigate the differences between the sample groups, a post-hoc "Tukey" test was undertaken. A 5% level of significance was used in the statistical study (P 0.05).

RESULTS AND DISCUSSIONS:

Microbial study of guava juice

Microbiological characteristics are prepared guava jelly's safety, quality, and shelf life. The number of bacteria that can grow and form countable colonies on nutrient agar after incubating at 37^oC for 24 hours is the total viable bacterial count in a sample. This study was performed by the standard plate count method. The number of viable bacteria was determined by multiplying the colony-forming unit (CFU) with the dilution number. The total numbers of viable bacteria in samples X and Y with pectin and citric acid variation, respectively, have been shown in Table 1 at 01, 30, 60, 90, and 120 days of storage. An initially significant amount of bacterial load was not detected, but bacterial load gradually increased after 60 days of storage. Investigation of Yeast and mold growth was performed at 30 days intervals. No significant amount of fungal growth was detected in 7 days of incubation in Sabouraud Dextrose agar. After 90 days of storage, Yeast and mold development was seen.

Techno-economic feasibility of guava jelly:

The production cost of the developed guava jelly was calculated for 10Kg guava is approximately Tk. 1300. As shown in Table 2, the production cost was approximately Tk. 130 per Kg. To make a bottle of 500g it will cost about 65 Tk. The retail price of the imported guava jelly found in the super shop is Tk. 630 per kg. A local Bangladeshi brand found in the market that's the price is Tk. 250 per Kg.

According to Table 1, it was clear that the bacterial count was not uniform at this period, and there was no apparent fluctuation over time. Total viable bacteria for both treatments were not detected in 1 day. It was found (1.1−1.3)×10 CFU/ml and (1.3−1.6)×10²CFU/ml bacterial count in 30 days and 60 days, respectively. The highest total viable bacterial count (1.5−1.7) ×10⁵ CFU/ml was found in 120 days. Bacterial load in 120 days was above the acceptable limit (≥10⁵CFU/ml) reported.²⁷ in guidelines for the microbiological examination of ready-to-eat foods. For the production of high-quality fruit juice and jelly, free from any microbial contamination, the use of good quality raw material is essential. Jellies obtained from damaged and bruised fruits contain more bacterial counts than the juice obtained from good fruits. Yeast and mold were not established in the guava jelly during 90 days of storage, showed in Table 1. The mold is an aerobic organism and cannot propagate well under inadequate oxygen conditions.²⁸ On the other hand, Yeast can reproduce in aerobic and anaerobic conditions. Acid/alkaline necessities for yeast and mold growth in a wide range of food products are fairly broad, fluctuating from pH 2 to above 9. Due to preserving jellies in air-tight bottle yeast, mold growth was inhibited. As far as pathogen growth rates are concerned, time is essential. Therefore, when determining a product's shelf life, food manufacturers take into account the time-related microbial growth. The time it takes for a product to reach the point where it is ready for consumption or usage is known as the shelf life. The shelf life of a product is influenced by a variety of factors, including the product's organoleptic quality and microbiological safety. Hence, the product's microbiological safety is the most important factor in this report. For perishable food items, the Uniform Open Dating Regulation mandates the use of a "sell-by" date to indicate how long they have left on the shelf.²⁹

Table 2: Production cost of guava jelly

Heads	Tk./Kg	The quantity used (kg/10kg products)	Total Tk.
1) Expenditure Rawmaterials
Fresh Guava	90	5	450.00
Sugar	55	4	220.00
Pectin	12000	0.015	180.00
Citric acid	180	0.060	11.00
Subtotal			861.00
2) Processing cost @ 15% of raw material			129.15
3) Bottling cost	25 Tk./piece	10 pieces	250.00
4) Handling cost excluding Raw materials @ 7% of raw material			60.27
The total production cost of 10 kg of guava jelly			1300.42

CONCLUSIONS:

Guava jellies were tested for their microbiological qualities. Pectin and citric acid were used in different concentration in preparation and preservation. Three different formulations of pectin and citric acid were used to make guava jelly, which was then refrigerated at room temperature (25–30°C). Until day 90 of the storage period, there was no sign of yeast or mould development. However, following 90 days of pectin and citric acid treatment, the total bacterial load in jelly (acceptable limit 105cfu/ml) is sufficient for eating. Furthermore, the cost of producing a bottle of 500g of the product was roughly 65 Tk, which is less expensive than other local brands. Therefore, this formulation might be used to help the country's agricultural and food sectors grow.

ACKNOWLEDGEMENTS:

The authors would like to acknowledge the Department of Applied Food Science and Nutrition Chattogram Veterinary and Animal Sciences University, Chattogram, Bangladesh, for research support facilities and Universiti Terengganu Malaysia for the UMT/TAPE-RG/2021/55328 grant provided to Chaudhry GS.

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Received on 30.03.2022 Modified on 22.07.2022

Research J. Pharm. and Tech 2023; 16(3):1351-1354.

DOI: 10.52711/0974-360X.2023.00222