Modulation of the food microbiome by apple fruit processing.

Area of Science:

• Microbiology
• Food Science
• Gut Microbiome Research

Background:

• Early life exposure to solid foods shapes the gut microbiota.
• Fruits and vegetables are crucial in early childhood diets.
• The role of fruit indigenous microbiota in food processing and infant gut health is understudied.

Purpose of the Study:

• To investigate apple fruit microbiota composition and diversity before and after various processing methods.
• To assess the impact of heat and mechanical treatments on fruit-associated bacteria.
• To identify potential probiotic properties of surviving fruit microbes.

Main Methods:

• Utilized advanced microscopic and sequencing technologies (16S rRNA gene sequencing).
• Performed functional assays to evaluate bacterial traits.
• Quantified bacterial abundance and diversity across different processing stages (shredded, boiled, pureed, preserved, dried).

Main Results:

• Unprocessed apples host abundant and diverse bacteria (Shannon index = 2.5).
• Processing reduced bacterial abundance and diversity, with shredded > boiled > pureed > preserved > dried.
• Boiling and air drying allowed a significant fraction (1/3) of microbes to survive, shifting the community composition and increasing relative abundance of Pseudomonas and Ralstonia.

Conclusions:

• Food processing significantly impacts fruit microbiota, altering bacterial composition and abundance.
• Certain surviving fruit microbes, particularly Bacillus species, exhibit probiotic potential (antagonist activity, bile salt resistance).
• Fruit-associated microbes represent a potential resource for modulating the infant gut microbiome, challenging their perception solely as a food safety risk.