Use of donkey’s milk for a fermented beverage with lactobacilli

Abstract

-The possibility of producing a fermented beverage from donkey's milk using the probiotic bacterial strains Lactobacillus rhamnosus AT 194, CLT 2/2, and Lactobacillus casei LC 88, isolated from Parmigiano Reggiano cheese was investigated. The chemical-physical and microbiological properties of the raw milk demonstrated that it has a low microbiological load and an elevated content of lysozyme. The bacterial strains employed for fermentation had a good growth capacity in donkey's milk only after an initial adaptation phase. An extremely high percentage of viable bacteria were found in the final beverage, even after a 30-day shelf life. Likewise, the activity of lysozyme was virtually unchanged with respect to initial values. Sensorial analysis permitted the individuation of differences between the three bacterial strains used for fermentation in terms of descriptors relative to aromatic-olfactory qualities. Based on the above results, technology can be proposed for production of a fermented beverage from donkey's milk that can be utilized by small producers. This would allow the production of a beverage that would be well accepted by consumers interested in a product with favorable therapeutic properties integrated with probiotic bacteria. CLT 2/2 et la souche Lactobacillus casei LC 88 toutes isolées du fromage Parmigiano Reggiano. Le lait, caractérisé du point de vue physico-chimique et microbiologique, a comme caractéristiques prédominantes une charge microbienne faible et un contenu en lysozyme élevé. Les souches utilisées ont montré une bonne capacité de développement dans le lait d'ânesse seulement après une phase d'adaptation. Les bactéries inoculées sont restées vivantes plus de trente jours dans les boissons obtenues, garantissant ainsi une longue durée de conservation. Au terme de l'essai, l'activité du lysozyme n'a présenté aucune variation sensible par rapport à l'activité initiale. L'analyse sensorielle à laquelle ont été soumises les boissons fermentées a permis de discriminer les différences induites par les trois souches utilisées en ce qui concerne quelques descripteurs relatifs au tableau aromatique et olfactif. Une technologie de production d'une boisson fermentée applicable à de petits ateliers artisanaux a donc été proposée, permettant d'obtenir un produit en mesure d'être accepté par un consommateur intéressé à la fois par les caractéristiques thérapeutiques du lait d'ânesse et les propriétés bénéfiques pour la santé des bactéries probiotiques.

A survey on the milk chemical and microbiological quality in dairy donkey farms located in NorthWestern Italy

“…This value is one order of magnitude higher than previously reported (Chiavari et al, 2005;Coppola et al, 2002;Salimei et al, 2004;Zhang et al, 2008). Regarding the LAB count, the overall mean number was 1.6*10 4 cfu/mL (Table 4).…”

Whey proteins and their antimicrobial properties in donkey milk: a brief review

“…The whole whey protein fraction of donkey milk is considered to be responsible for the low total bacterial count reported in literature (Chiavari et al 2005;Šarić et al 2012); the antimicrobial activity is mainly attributed to Lyz and, to a lesser extent, to Lf (Uniacke- Lowe et al 2010).…”

“…Donkey milk's Lyz is resistant to digestion: only the 25% of the total protein is digested in vitro by gastrointestinal juice (Tidona et al 2014). It is also thermostable even after a thermal treatment of 63°C for 30 min (Coppola et al 2002;Di Cagno et al 2004;Chiavari et al 2005). …”

“…) (Coppola et al 2002) and keeps a low value even during about 4 days of storage (Chiavari et al 2005;Šarić et al 2012). The high content of Lyz and other non-specific antimicrobial compounds gives to raw fresh donkey milk a long natural shelf life and makes a prolonged heat treatment unnecessary, which is normally required for preserving hygienic quality and nutritional properties.…”

“…The most common method of sanitization is the pasteurization at 63°C, which generally is not expected to affect the main nutritional and health properties (Coppola et al 2002;Chiavari et al 2005). Other preservation methods, such as drying (spray-drying and freeze-drying) or fermentation, allow a longer storage but can significantly affect milk protein composition and their functional properties.…”