Effects of lactic acid fermentation on the quality of different fruit purées.

The goal of a recent study, carried out by a Turkish researcher (Ucak-Ozkaya, 2024), was to create new probiotic fruit purées for lactose-intolerant people, vegetarians, and infants over 6 months old. The samples were prepared by subjecting apples, peaches and bananas to fermentation with different lactic acid bacteria (LAB) strains (Lactobacillus plantarum (S5), Lactobacillus fermentum (S10) and Lactobacilluspentosus (S14)).

The tests were conducted by varying the fermentation durations (24 and 48 h) and the inoculation ratios (4 and 5%), as well as the type of LAB. The results show that the parameters tested have a positive effect on the color of the purées, making it better than that of the control product. It has also been observed that the level of bioactive compounds decreased after fermentation in S10 and S14 samples, but increased in S5 samples.

The bacterial population in the samples subjected to the longest process ranged from 7.0 to 9.5 log CFU/g. In addition, the fruit purées exhibited the presence of two different phenolic compounds and 17 distinct volatile compounds (responsible for the aroma). In conclusion, the study revealed that the proposed approach shows high promise for the development of new fruit purées as carrier for live probiotics. However, further analysis is still needed to assess the influence of the fermentation process on other quality parameters, such as, in particular, sensory parameters, and shelf-life.

Effect of flash vacuum expansion on the quality of papaya purée

Papaya is subject to various deterioration issues throughout the supply chain, resulting in the loss of bioactive phytochemicals in the fruit pulp. Making purées is the best method to make papaya pulp last lonver, but processing can break down antioxidants like phenolic compounds (which are mostly stored in cell vacuols) and carotenoids (stored in chromoplasts). The flash vacuum expansion process (FVE) promotes an expansion of the water present in the vacuols, causing cell rupture and, consequently, the release of intracellular components.

Since cell rupture is promoted from within the cell, the expulsion of bioactive compounds is more efficient and can therefore increase their bioaccessibility. Therefore, a recent study, carried out by a team of Mexican researchers (de Jesus Castillo-Romero et al., 2024), investigated the effect of FVE technology on certain quality characteristics of papaya purée.

The results prove that the FVE process can increase the antioxidant capacity of the purées (measured by TEAC, FRAP and DPPH assays), before and after the digestion in vitro. In addition, the proposed approach significantly enhances the bioaccessibility and stability of antioxidant compounds, providing a clear advantage over conventional processes. In conclusion, papaya purée obtained by FVE can be an ingredient that increases the functionality of food, particularly suitable for people with digestive problems, and for baby food.

References: Ucak-Ozkaya, Food Science, 89, 2024, 6481-6493; de Jesús Castillo-Romero et al., Resources, 13, 2024, 175.