Physicochemical and microbiological parameters of rumen fluid of lactating goats fed diets containing crude glycerin from waste frying oil used in biodiesel production

Crude glycerin from the biodiesel industry is a alternative energy source used to replace part of the energy components of the diet, since the nutritional value of glycerol makes it suitable for use in ruminant diets. The objective was to analyze the effects including crude glycerin (CG) derived from the production of biodiesel from residual frying oil, in diets of lactating goats on the physicochemical and microbiological parameters of rumen fluid. Eight 2-year-old goats weighting approximately 42.06 ± 3.5 kg of body weight (BW) were kept in individual stalls, receiving diets containing 0, 7, 14 and 21% of CG (% DM). The experiment was carried out according to a double 4 × 4 Latin square and lasted for 80 days. Orthogonal contrasts were tested to determine linear and quadratic effects, as well as the effects of 0% CG in the diet in comparison to the other treatments. There was a linear decreasing effect on DM intake (P = 0.001) and neutral detergent fiber (P = 0.0001), as well as a quadratic effect (P = 0.0002) on ether extract (EE) intake with increasing level of CG in the diet. Including CG affected motility and density of the protozoa (P = 0.0001). Treatments had no effect on pH, N-NH3 concentration and percentage of protozoa in the rumen liquid. There was increasing linear effect on sedimentation and flotation time (P = 0.001). Therefore, including 14 and 21% CG in the diet as a source of glycerol decreased nutrient intake and altered the ruminal microbiota, but pH and N-NH3 were not affected. Thus, to avoid impairment to the physicochemical and microbiological parameters of the rumen liquid of goats, the inclusion of CG should not exceed 7% DM.

An Investigation of Several Physicochemical Characteristics, as Well as the Cholesterol and Fatty Acid Profile of Ice Cream Samples Containing Oleogel, Various Stabilizers, and Emulsifiers

This study investigated the possible usage of beeswax oleogels instead of milk fat as a fat source in ice cream production and konjac gum as a stabilizer instead of salep. For this aim, 12 different ice cream samples were prepared using various fat and oil sources (milk fat and oleogel), stabilizers (salep and konjac gum), and emulsifiers (monoglyceride (MG), Palsgaard (PG), and no emulsifier/emulsifier-free (NE)). It was determined that the overrun ratio of ice cream samples containing milk fat was higher than that of samples containing oleogel, and the viscosity of the ice cream mix containing Palsgaard and oleogel was greater than that of the mix with other treatments (milk fat, MG, and NE). While the first dripping time of the samples with PG and konjac gum was longer compared to the samples without emulsifier (NE) or monoglyceride (MG), the complete melting times of the samples were close to each other. Whereas the dissolution rate of the samples with salep was higher than that of the samples with konjac gum, the fat destabilization ratios of the samples with oleogel and konjac gum were lower than those of the samples with milk fat and salep. The fat destabilization ratio of samples containing PG as an emulsifier was statistically higher (p < 0.01) than that of samples containing MG and NE. It was found that the unsaturated fatty acid (C18:1, C18:2, and C18:3) content of the samples containing oleogel was significantly higher (p < 0.01) than that of the samples containing milk fat. However, butyric and caproic acids, which are aliphatic fatty acids, were found to be deficient in the samples to which oleogel was added instead of milk fat. As to the microscopic appearance, while water and oil particles were not homogeneously dispersed in the ice cream samples with oleogel, they were fully homogeneously dispersed in the milk fat-added ice cream samples. In addition, it was determined that panelists preferred the samples with added milk fat as fat source, salep, and PG as emulsifier. Among the samples with added oleogel as the oil source, they liked the sample added with oleogel as fat source, konjac gum, and no emulgator more.

Validation of the Methods for the Non-Milk Fat Detection in Artificially Adulterated Milk with Palm Oil

Dairy products are among the most adulterated food products. Due to the current high price of milk fat, it has been replaced by low-cost oils, especially those oils that have the same fatty acid profile as milk fat. This study intends to confirm the lowest level of palm oil added to milk and validate various methods for detecting palm oil in milk, including gas chromatography, reverse-phase high performance liquid chromatography, and Fourier transform infrared. Different amounts of palm oil were prepared in the final liquid milk using five treatments of fresh milk cream and an emulsion of palm oil. The results of this study showed that the values of the saponification number decreased with the increase in the percentages of added palm oil. There was no decrease under the limits of the Egyptian standards until the addition of 50% palm oil. The iodine number is less sensitive than the saponification number in the detection of palm oil. Butyro refractometer reading is unable to detect the palm oil in milk. The fatty acid profile in milk determined by gas chromatography correlated well with the addition of palm oil. Furthermore, there is a positive relationship between the level of added palm oil and the β-sitosterol content as measured by reverse-phase high-performance liquid chromatography. There was no relationship between the behavior of the spectra resulting from Fourier transform infrared spectroscopy and the presence of palm oil.

Sweet potato peel flour in hamburger: effect on physicochemical, technological and sensorial characteristics

Abstract The aim of this research was to evaluate the influence of sweet potato peel flour (SPPF) on the physicochemical, technological and sensorial characteristics of bovine hamburger. Four hamburger formulations were prepared added SPPF: F1 (0%), F2 (0.75%), F3 (1.5%) and F4 (2.25%). The flour was characterized by high levels of minerals, carbohydrate and dietary fiber, which improved the nutritional profile of the hamburger. There was an increase in moisture retention and shrinkage, as well as a reduction in fat retention and cooking yield, as the level of SPPF addition increased. The addition of flour in the product significantly reduced (p < 0.05) the values of L*, a* and b*. Similar acceptability to the standard sample was checked for the hamburger with the addition of up to 1.5% SPPF. However, all formulations had an acceptability index greater than 70%. It is concluded that SPPF is a potential ingredient to be added in bovine hamburger, improving nutritional and technological parameters and with low influence on the sensorial characteristics.

Use of β-glucan from spent brewer's yeast as a thickener in skimmed yogurt: Physicochemical, textural, and structural properties related to sensory perception

Powdered β-glucan extracted from brewer's yeast (Yestimun, Leiber GmbH, Bramsche, Germany) was incorporated into skimmed-milk yogurt at varying concentrations (0.2-0.8% wt/wt) to investigate its potential application as a thickener. The effect of β-glucan fortification on the nutritional profile, microstructure, physicochemical properties, and texture of freshly prepared yogurts was investigated. Sensory evaluation was also conducted and was correlated with instrumental analysis. The addition of Yestimun significantly reduced the fermentation time of the yogurt mix from 4 h to 3 h. Scanning electron microscopy revealed that β-glucan particles formed small spherical clusters within the yogurt matrix. The majority of the physicochemical properties (syneresis, viscosity, color, and titratable acidity) remained unaffected by the incorporation of Yestimun in the recipe. Textural properties showed a gradual increment with increasing β-glucan concentration. Hardness, total work done, adhesive force, and adhesiveness increased by 19.27, 23.3, 21.53, and 20.76%, respectively, when using the highest amount of Yestimun powder. Sensory analysis (n = 40) indicated that fortifying yogurt with Yestimun at 0.8% (wt/wt) concentration may affect overall acceptance ratings, which was attributed to adverse flavor and aftertaste effects. However, the overall liking score of the yogurt (5.0/9.0) shows potential for commercialization of the product.