A Multi-Omics Approach to Evaluate the Quality of Milk Whey Used in Ricotta Cheese Production

Abstract

In the past, milk whey was only a by-product of cheese production, but currently, it has a high commercial value for use in the food industries. However, the regulation of whey management (i.e., storage and hygienic properties) has not been updated, and as a consequence, its microbiological quality is very challenging for food safety. The Next Generation Sequencing (NGS) technique was applied to several whey samples used for Ricotta production to evaluate the microbial community composition in depth using both RNA and DNA as templates for NGS library construction. Whey samples demonstrating a high microbial and aerobic spore load contained mostly Firmicutes; although variable, some samples contained a relevant amount of Gammaproteobacteria. Several lots of whey acquired as raw material for Ricotta production presented defective organoleptic properties. To define the volatile compounds in normal and defective whey samples, a headspace gas chromatography/mass spectrometry (GC/MS) analysis was conducted. The statistical analysis demonstrated that different microbial communities resulted from DNA or cDNA library sequencing, and distinguishable microbiota composed the communities contained in the organoleptic-defective whey samples.

Volatile aroma composition of distillates produced from fermented sweet and acid whey

“…It is standard practice to freeze samples when storing for aroma analysis by GC-MS, as this causes any potential aromatic reactions to stop (Jervis et al, 2015;Izawa et al, 2015). Although we could not find any research specifically into potential aroma or aroma precursor changes in whey due to freezing, Sattin et al (2016) used HS-SPME-GC-MS on frozen and fresh whey samples and found no relationship for aroma composition based on fresh versus frozen whey. This suggests that it is the further treatment of the whey and not the frozen versus fresh storage that is responsible for aroma composition.…”

Enhanced Aromatic Profile and Functionality of Cheese Whey Beverages by Incorporation of Probiotic Cells Immobilized on Pistacia terebinthus Resin

“…Methyl-ketones have been previously reported as significant volatile organic compounds in dairy samples, with those between 5 and 13 carbon atoms (detected in all samples) contributing a flavor that resembles that of fruit [76]. For example, 2-heptanone contributes a green fruity flavor, while 2-nonanone contributes a malty fruity flavor.…”

“…Diacetyl is considered as a key odor compound for the buttery smell of the products. Its production is usually attributed to high production temperatures and/or the presence of various bacterial strains, while citrate is reported as a common substrate for its production [76]. It is worth noting that in our case, both high temperatures and citric acid are applied.…”

“…Aldehydes are major oxidation products of unsaturated fatty acids. Among them, hexanal (found in all samples) is considered a typical marker of the oxidative processes and is characterized by an intrinsic leafy green smell [76], while most aldehydes are considered contributors of the metallic flavor attributes of liquid whey [71]. 2-octenal, which was found in all samples, is characterized by a cucumber flavor, while 3-methyl-butanal (also identified in all samples) presents a cocoa malty flavor.…”

High-Throughput Sequencing Technologies and new Approaches in Food Microbiology

“…Furthermore, HTS techniques have been applied to several samples of ricotta to evaluate the microbial community composition in depth using both RNA and DNA as templates for NGS library construction [31]. An integrated analysis based on multi-omics approach gave us the opportunity to better understand how plants modulate their response to different environments [32].…”