Effectiveness evaluation of alternative sanitizers in microbiological quality of strawberry (Fragaria ananassa Duch Var. Oso Grande) after artificial contamination by Escherichia coli

Abstract

Washing and sanitization are considered particularly critical steps for the microbiological quality of fruits. At this stage, it is important to select the sanitizer which must have microbiological effectiveness. On the literature, there is a great interest on alternative sanitizers for microbiological quality control of food. This study aimed at verifying the effectiveness of sodium hypochlorite, ozone, ultrasound and citric acid as well as associations of ultrasound to the other techniques mentioned above in the microbiological quality control of strawberries cv. Dso Grande. On these trials, the fruits were initially subjected to artificial contamination by a strain of Escherichia coli ATCC 25922 and thereafter part of them was reserved as control samples; the remainder was submitted to different kinds of sanitization treatment. Then, some microbiological analyses of coliforms counts at 45 °C were performed with those present in the control samples and in the post-sanitization samples, through the enzymatic technique of chromogenic substrate. The three most efficient treatments for maintaining the microbiological quality of the fruit were 2% citric acid, 2% citric acid associated with ultrasound and ozone.Practical Application: This work could provide subsidies for the use of alternative sanitizers, for example, in minimum fruit processing methodologies in micro and large industries.

Application of Ultrasound Combined with Acetic Acid and Peracetic Acid: Microbiological and Physicochemical Quality of Strawberries

“…Outbreak records involving the consumption of fresh food contaminated with pathogenic microorganisms highlight the need for improvement in the postharvest sanitization of these products [1][2][3]. Chlorine-based compounds, especially sodium hypochlorite, are commonly used during the sanitization of vegetables to control such outbreaks [4][5][6]. In Brazil, as occurs in other countries, chlorine compounds are the most used sanitizers for fruits and vegetables because they are cheap, easy to prepare and have an antimicrobial efficiency [4,5].…”

“…In Brazil, as occurs in other countries, chlorine compounds are the most used sanitizers for fruits and vegetables because they are cheap, easy to prepare and have an antimicrobial efficiency [4,5]. However, there are questions about the efficiency of chlorine-based solutions on biofilms as well as the chemical reactions of free chlorine with organic matter in wash water, which can produce carcinogenic toxic products such as trihalomethanes and haloacetic acids [4][5][6][7]. For this reason, chlorinated compounds are banned in some European countries, such as Germany, Switzerland, the Netherlands, Denmark and Belgium [8,9].…”

“…Studies have reported that applications of ultrasound combined with other procedures and/or antimicrobials may increase the inactivation of microorganisms [19,24]. Ultrasound is classed as nonthermal, and it is capable of extending shelf life, decreasing microbial counts and preserving nutritional and sensorial qualities [12], but in some conditions can affect fruit characteristics [6,17].…”

“…According to Bastos et al [6], ultrasound can be an excellent candidate for using on fruits such as strawberries. Strawberry (Fragaria ananassa Duch.)…”

“…Strawberry (Fragaria ananassa Duch.) is considered a healthy product and is one of the most eaten fruits due nutritional and bioactive properties [6]. However, it is a highly perishable fruit, because of its high contents of water and carbohydrates; as a result, it is extremely probable to have undergone microbiological contaminations from the environment [6,[25][26][27].…”