Lactic acid fermentation of osmo-dehydrated onion

Area of Science:

• Food Science
• Microbiology
• Biochemistry

Background:

• Onions are rich in polyphenols and fructo-oligosaccharides.
• Lactic fermentation is a valuable preservation technique.
• Osmotic dehydration is a pre-treatment method for food processing.

Purpose of the Study:

• To evaluate the impact of osmotic dehydration on lactic fermentation efficiency.
• To assess the effect on polyphenol and oligosaccharide content in onions.
• To investigate different onion varieties and fermentation strains.

Main Methods:

• Osmotic dehydration of yellow and red onion varieties (Alonso, Hysky, Hystore, Red Lady) using sucrose and sodium chloride solutions.
• Lactic fermentation using Levilactobacillus brevis 0944.
• Analysis of lactic acid isomers, polyphenol content, and fructo-oligosaccharides.

Main Results:

• Osmotic dehydration generally did not negatively affect bacterial growth or numbers.
• Dehydration positively modified lactic acid isomer profile, increasing L (+) isomer proportion.
• Polyphenol content remained unaffected by osmotic dehydration.
• Fructo-oligosaccharide loss was limited, with 60% retained using 'Alonso' cultivar and L. brevis 0944.

Conclusions:

• Osmotic dehydration is a suitable pre-treatment for onions before lactic fermentation.
• This method can enhance fermentation characteristics and preserve valuable compounds.
• Specific onion cultivars and bacterial strains optimize compound retention.