Influence of Three Extraction Methods on the Physicochemical Properties of Kefirans Isolated from Three Types of Animal Milk

Abstract

Kefiran is a heteropolysaccharide biopolymer usually extracted from kefir grains cultured in cow milk. Due to the lack of information on exopolysaccharides from other types of animal milk, in the present study, cow, buffalo and goat milks were used as raw materials for fermentation. The kefiran extractions from kefir grains were carried out with cold water (method I), hot water (method II) and mild heated water-ultrasound (method III), and then the recovery yield and the physicochemical properties of the kefirans were evaluated to establish the influence of both the extraction conditions and the type of milk. The highest yield was recorded for the cow kefiran using method III (4.79%). The recoveries of goat and buffalo kefirans with methods II and III were similar (2.75–2.81%). Method I had the lowest yields (0.15–0.48%). The physicochemical characteristics were studied with Fourier Transform-Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). Fourier-transform infrared spectroscopy showed the same qualitative profile for all the samples, regardless of the method and the type of milk, confirming that the extraction methods did not affect the chemical structure of the kefirans. Otherwise, the thermal and morphological features of the samples showed differences according to both the type of the milk and the extraction method. The kefiran samples were very thermally stable, having a temperature of degradation (Td) in the range from 264 to 354 °C. The resulting morphological and thermal differences could lead to different practical applications of kefirans in the fields of nutrition and pharmacology.

Comparing Nutritional Values and Bioactivity of Kefir from Different Types of Animal Milk

“…The phenol–sulfuric acid colorimetric method was applied to all milk samples in order to evaluate their sugar content [ 85 ]. Then, 0.1 mL of samples, previously diluted with distilled water (1:10), was mixed with phenol solution (1 mL, 6% w / v ) and H 2 SO 4 (1 mL) for 5 min at room temperature, and then left to stir in a boiling water bath for 15 min.…”

Improved Antioxidant Properties and Vitamin C and B12 Content from Enrichment of Kombucha with Jujube (Ziziphus jujuba Mill.) Powder

“…Protein content was determined by Bradford assay with some modifications [28]. Briefly, 20 µL of sample (1 mg/mL) and 200 µL of Coomassie Brilliant blue reagent were added to 800 µL of distilled water.…”

“…The protein concentration of all samples was determined using the method developed by Bradford [28] and is shown in Figure 2. The results show that the protein content of K1 significantly increased (0.39 ± 0.02 mg/100 mL, * p < 0.05) during the first day of fermentation compared to the control T (0.25 ± 0.08 mg/100 mL).…”

Spectroscopic technologies and data fusion: Applications for the dairy industry

“…Spectroscopy has become a commonly used technique due to its ease of use and application across a wide range of food nutrients, and the availability of powerful downstream chemometric tools for data interpretation. Different spectroscopy techniques have been applied to measure composition, authenticity ( 3 ), adulteration ( 4 ), physicochemical ( 5 ), and organoleptic characteristics in dairy applications. However, each method is limited in the information it can provide, often leading to poor or inaccurate calibrations.…”