INTRODUCTION:

Eating fruit has a recognized positive effect on health, associated with its high quality and richness in essential nutrients such as carbohydrates and vitamin C, known for its antioxidant potential. Regular consumption of fruit and vegetables guarantees a diet rich in vitamins and minerals. This consumption protects the body from numerous diseases, such as cardiovascular disease, diabetes and excess lousy cholesterol¹. However, the daily consumption of fruit and vegetables recommended by the French National Nutrition and Health Plan seems difficult to achieve. High prices, seasonality, fragility and short shelf life are the main obstacles to the consumption of these products².

Physicochemical, microbiological and organoleptic controls in the food industry cover products' nutritional, hygienic and organoleptic qualities.

A global approach must be applied to rigorously control industrially manufactured products' microbiological quality and chemical stability. It involves the development of the production process, the design of equipment, hygiene and staff training, and the organization and management of production^3,4.

Today's cultivated strawberry (Fragaria X ananassa Duch.) is the result of a cross between a North American strawberry (Fragaria virginiana Duch.) and a South American strawberry company (Fragaria chiloensis (L) Duch.). Five samples of the latter species were brought back from Chile by the Frenchman Frézier in August 1714. This cross, first described by Antoine Duchesne, is vigorous and produces large strawberries. They are obtaining Fragaria X ananassa Duch. is of greater economic interest than F. vesca, F. moschata or F. virginiana. The discovery of new species has led to other crosses, but Fragaria x ananassa Duch. It is currently the most widely cultivated species⁵.

Climate plays a fundamental role in strawberry growth, depending on the season and the state of the plant. In summer, plants tend to grow vegetatively. When autumn arrives, temperatures drop, initiating flowering, and it is in spring that the fruiting phase begins.^6–8.

Strawberries are 90% water and relatively low in carbohydrates. It is also low in calories and rich in vitamins, the most interesting of which is vitamin C, which is involved in the body's primary functions, as well as B-class vitamins (B8 biotin, which plays a role in combating hair loss, and B9 folic acid, which plays a role in cell growth and division), plus trace elements and macronutrients.^9,10

It is one of the richest fruits in fibre; its berries are composed of pectin and cellulose, which are beneficial for transit and the functioning of the digestive system. This fruit also contains significant ellagic acid¹¹.

Flavonoids are the main phenolic compounds found in strawberries and are among the compounds that contribute most to their antioxidant capacity ^12–17. Anthocyanins are responsible for the reddish-orange colour of strawberries and are thought to have a protective effect against cancer^18–21.

The present work has been carried out at a Moroccan company to monitor the production process for red fruit products through a series of physicochemical, microbiological and organoleptic analyses of strawberry pulp before and after pasteurization to determine its quality. The main objective of our present work is to find adequate pasteurization conditions to eliminate pathogenic microorganisms while preserving the organoleptic quality of the finished product and reducing energy losses through a series of experiments and trials within this company.

MATERIALS AND METHODS:

Once the raw material has been validated in a first inspection by the naked eye, physicochemical and microbiological checks are carried out on samples of aseptic strawberry pulp taken (at the beginning, in the middle and at the end) before and after pasteurization.

Physico-chemical analysis:

Hydrogen potential (pH):

The pH is determined directly using an electronic pH meter. This device must be calibrated every morning with two buffer solutions (pH= 7, pH= 4).

Brix measurement:

The refractometry index, or Brix, is the percentage of soluble dry matter contained in a solution. It is used to estimate the sugar content in fruits. Their principle is based on the refraction of light. The refractometers give, by simple reading, the dry extract of the liquid sweetened at 20°C. The measurement technique consists of the following steps:

· Clean the refractometer prism with soft paper.

· Measure a small portion of the product into the prism.

· Press START. The instrument shows the value in the viewfinder in Brix corrected for 20°C.

Viscosity measurement:

Viscosity measures the fruit's resistance to flow. It is carried out at 20°C. Using a Bostwick Consistometer, the value should be between 8 and 12(cm2/s).

This operation is carried out one day after sampling;

· Take a sample at an average temperature of 20°C after mixing well;

· Pour the product into the device's receptacle, shaving off any excess with a spatula;

· At the same time, switch on the viscometer door and the stopwatch.

· Read results in cm/min after 60 seconds.

Retained material:

This analysis aims to determine the quantity of fruit pieces present in the finished product. It involves carefully mixing 200g of the product to be analyzed with 2000g of water at room temperature. The mixture is poured onto the sieve (9mm), using a slight manual movement to drain off all the product passing through the sieve, and then the quantity of fruit pieces retained in the sieve is weighed. The percentage of fruit pieces is calculated using the following formula:

Quantity retained - Sieve weight

Retrievable % = ------------------------------------- X 100

200

Microbiological Analysis:

To ensure a healthy product, the company conducts microbiological analyses based on detecting three microorganisms: yeasts/moulds, enterobacteria and total aerobic mesophilic flora (TAMF), after pasteurization to determine product quality.

After pasteurization, samples were taken in aseptic bags. The product was then manually poured into flasks prior to microbiological testing. The following cultural media were used (Table 1):

Table 1: Culture media used for microbiological analyses

Strains	Yeasts and moulds	Total flora	Enterobacteria
culture media	Yeast Glucose Chloramphenicol (YCG)	Plate Count Agar (PCA)	Violet Red Bile Agar (VRBG)

After preparing the mother suspension by adding 10g of product to 90mL of EPT, 1mL of this suspension is inoculated into each dish and incubated at 26°C/3 days for fungi and 37°C/24 h for bacteria²².

Enumeration of the total flora:

The culture medium used to enumerate this flora is PCA. The PCA agar was melted and kept supercooled at 45°C, then poured into Petri dishes containing 1mL of the sample to be analyzed, prepared as above (three Petri dishes for each sample) to carry out mass plating. The sample and agar were mixed and left to solidify on the bench. The plates were incubated at 30°C for three days. Another plate was prepared as a control, containing only the PCA medium²³.

Enumeration of yeasts and moulds:

Yeasts and moulds were counted on YCG medium. Inoculation was carried out on three deep plates at 1 mL per plate, followed by incubation at 25°C for three to five days. Readings were taken every day to monitor growth^24,25.

Enumeration of Enterobacteria:

· VRBG agar is used to detect and enumerate enterobacteria in food products.

· Transfer 1 mLof the suspension and its successive decimal dilutions into sterile Petri dishes.

· Pour in approximately 15 mL of medium per dish.

· Mix thoroughly and allow to solidify on a cold surface.

· Pour a further 5 mL of medium to form a second layer.

· Allow to solidify.

· Incubate at 37°C for 24h(ISO, 2013).

RESULTS AND DISCUSSIONS:

Before pasteurization:

Physico-chemical analyses were carried out to determine various physicochemical characteristics. These analyses were carried out on the raw material (fresh strawberries) just after the first observations at reception, and the results obtained are shown in Table 2, which gives the average values for each of the four days during a month of sampling. These analyses carried out on our samples for one month have shown that the values of the parameters measured during reception comply with the standards. This means that this raw material is of good quality and that the first control stage has been carried out successfully.

After pasteurization:

The figures1,2,3 show the results of analyses carried out on samples taken at the purple container's beginning, middle and end.

Figure 1: pH analysis after pasteurization

The pH values measured for pulp concentrates are characterized by stabilization after pasteurization (Figure 1) and in the various product levels, meeting the standards set by the company (3.2 - 3.8).

We also note that Brix levels (Figure 2) align with the values set by the company (6 - 12). These variations in sugar content in the samples analyzed may be due to the nature of the strawberries used (sugar composition) to manufacture the different pulp concentrates. Viscosity values (Figure3) meet company requirements (8-13), with a minimum value of 2.5 in the middle and a maximum of 4.3 at the beginning. The results obtained, illustrated in figure 1, concerning the fruit found, are in line with the company's standards.

It should be noted that these values fixed by the company are variable, depending on customer requirements.

Figure 2: Brix analysis after pasteurization

Figure 3: Viscosity analysis after pasteurization

Microbiological analysis:

The evolution of the number of microorganisms in strawberry pulp depends on several factors that can promote or inhibit their development. This depends on the composition of the strawberry pulp and storage and transport conditions. The results of the microbiological analyses carried out are shown, Bellow:

During our work and after the pasteurization stage, we evaluated the organoleptic and microbiological quality of the finished product by changing the pasteurization temperature and duration. The table 3 shows the different pasteurization conditions and the results obtained:

Table 3: Variation in organoleptic characteristics as a function of chambering

Heattreatment	Temperature °C	100	94	87	85	89
	Time (min)	1.5	3	5	7.5	4.6
	Colour	NC	NC	NC	C	C
	Taste	NC	NC	C	C	C

NC: Not in conformity; C: conform

It can be seen from the above table that the organoleptic quality of the finished product depends on pasteurization conditions. The optimum pasteurization conditions for obtaining a compliant finished product are 85°C/ 7.5 min and 89°C/ 4.6 min. Other pasteurization temperatures degrade the organoleptic quality of the finished product.

Table 4: Microbiological analysis of strawberry pulp finished product

Microorganisms	Total flora	Yeasts and moulds	Enterobacteria
Pasteurization (85 °C / 7.5min)	Absent	Absent	Absent

After pasteurizing the strawberry pulp at a temperature of 85°C/7.5min, microbiological analyses of the finished products have shown that they comply with standards and do not contain microbiological agents such as TAMF, yeasts, moulds and enterobacteria (Table 4).

Enumeration of Total aerobic mesophilic flora:

After pasteurization, there was a total absence of microorganisms in the analyzed sample, which complied with the company's standard.

Enumeration of yeasts and moulds:

The results show a total absence of these microorganisms in the pasteurized product. For mould counts, the results obtained for the samples studied showed their absence after pasteurization, which is consistent with company standards.

Enumeration of Enterobacteria:

The results obtained for enterobacteria showed an absence of these microorganisms in the sample taken after pasteurization, implying a satisfactory microbiological quality within the company's standards.

According to the results of microbiological analyses on the finished product, no alterations were noted, i.e. a total absence of microorganisms. This could be due to the effectiveness of the heat treatment, which eliminates all pathogenic agents.

Moreover, the strawberry pulp samples analyzed had acidic pH values, further eliminating microorganisms that could not tolerate low pH values, thanks to the organic acids in the fruit. As a result, we can deduce that the product is of good microbiological quality according to current regulatory specifications²⁶.

Concerning the organoleptic characteristics of the finished product, we tried to preserve the taste and colour of strawberry pulp by changing the temperature and duration of pasteurization to minimize cost and energy losses.

The product subject to heat treatment shows variations in colour and taste depending on the temperature and duration (chambering) adopted compared to the conditions within the company (89°C for 4.6 min) during treatment. At 85°C for 7.5 min, the finished product's taste, colour and microbiological quality were preserved.

The results aligned with the standards once the various germs were identified and counted. The efficiency of the heat treatment can explain these results, the acidity of the product, the excellent storage conditions of the product and the use of an aseptic production line which allows a long shelf-life of 1 year at a temperature between 0-10°C without the addition of preservatives.

CONCLUSION:

In the agri-food industry, the quality and stability of manufactured products have become an indispensable criterion and an undeniable requirement for companies faced with increasingly tough competition. The study carried out at the fruit production company aimed to assess the physicochemical, organoleptic and microbiological quality of the raw material and the finished product and to monitor its stability under conditions favourable to spoilage and quality deterioration.The results of the various physicochemical, organoleptic and microbiological analyses carried out on the strawberry pulps enable us to confirm that they are of good quality and consequently comply with the standards in force, revealing, on the one hand, the excellent quality of the raw materials used, and on the other the good practice of hygiene rules. In addition, the continuous monitoring of production parameters has enabled us to manage this technology better. Heat treatments (pasteurization, sterilization) are controlled, and the product is aseptically packaged to protect it from contamination. Therefore, we can confirm that the finished product analyzed is of good microbiological quality and complies with standards.

Prospects include finding the conditions for efficient pasteurization, eliminating pathogenic microbial populations while maintaining the organoleptic quality of the finished product and consequently reducing pasteurization time and energy losses within the company.

CONFLICT OF INTEREST:

All the authors declare that there is no conflict of interest.

ACKNOWLEDGEMENT:

Thanks to the research team in Laboratory of Natural Resources and Sustainable Development,Faculty of Sciences.

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Received on 13.11.2023 Modified on 07.02.2024

Research J. Pharm. and Tech 2024; 17(6):2505-2509.

DOI: 10.52711/0974-360X.2024.00392

Period	pH	Standards	Brix	Standards	Calibre	Standards
13-16/03/2019	3,35	Values required by the customer 3,2-3,8	7,72	Values required by the customer 6-12	34,5	Values required by the customer >25
17-20/03/2019	3,65		8,5		47
21-24/03/2019	3,47		8,75		56,5
25-28/03/2019	3,5		8,82		61,5
29-01/03/2019	3,35		7,05		58
02-05/04/2019	3,47		9,55		50,5
06-09/04/2019	3,5		9,52		6,5
10-13/04/2019	3,55		10,75		61,5