Dominique Ibarra

Influence of Composition (CO2 and Sugar) on Aroma Release and Perception of Mint-Flavored Carbonated Beverages

The aim of the present work was to identify and quantify physical mechanisms responsible for in-nose aroma release during the consumption of mint-flavored carbonated beverages in order to better understand how they are perceived. The effect of two composition factors (sugar and CO(2)) was investigated on both the sensory and physicochemical properties of drinks by studying in vitro and in vivo aroma release. Sensory results revealed that the presence of CO(2) increased aroma perception regardless of the sugar content. In agreement with volatility parameters, in vivo measurements showed that carbonated drinks released a greater quantity of aroma compounds in the nose space than non-carbonated ones. CO(2) seemed thus to induce large modifications of the physicochemical mechanisms responsible for the aroma release and flavor perception of soft drinks. Moreover, sugar content seemed to have an impact (increase) on aroma perception only in the case of non-carbonated beverages. Sensory interactions were thus observed, in particular, between sweet and aroma perceptions. For carbonated beverages, sugar content had an impact only on aroma release, but not on their perception.

Chapter 28 – Influence of Composition (CO2 and Sugar) on Aroma Release and Perception of Mint-Flavored Carbonated Beverages

The aim of this study was to quantify the effects of sugar and CO2 contents on the sensory and physicochemical properties of mint-flavored carbonated beverages, combining sensory and instrumental dynamic methods. Sensory results revealed that the presence of CO2 increased aroma perception regardless of the sugar content. In agreement with volatility parameters, in vivo measurements showed that carbonated drinks released more aroma compounds in the nose space than non-carbonated ones. Sugar content increased aroma perception only in the case of non-carbonated beverages, highlighting the existence of sensory interactions between sweet and aroma perceptions. For carbonated beverages, sugar content had an impact on aroma release, but not on aroma perception.

Phospholipolysis Caused by Different Types of Bacterial Phospholipases During Cold Storage of Bovine Raw Milk Is Prevented by N2 Gas Flushing

Cold storage aims to preserve the quality and safety of raw milk from farms to dairies; unfortunately, low temperatures also promote the growth of psychrotrophic bacteria, some of which produce heat-stable enzymes that cause spoilage of milk or dairy products. Previously, N2 gas flushing of raw milk has demonstrated significant potential as a method to hinder bacterial growth at both laboratory and pilot plant scales. Using a mass spectrometry-based lipidomics approach, we examined the impact of cold storage [at 6°C for up to 7 days, the control condition (C)], on the relative amounts of major phospholipids (phosphatidylethanolamine/PE, phosphatidylcholine/PC, phosphatidylserine/PS, phosphatidylinositol/PI, and sphingomyelin/SM) in three bovine raw milk samples, and compared it to the condition that received additional N2 gas flushing (N). As expected, bacterial growth was hindered by the N2-based treatment (over 4 log-units lower at day 7) compared to the non-treated control condition. At the end of the cold storage period, the control condition (C7) revealed higher hydrolysis of PC, SM, PE, and PS (the major species reached 27.2, 26.7, 34.6, and 9.9 μM, respectively), compared to the N2-flushed samples (N7) (the major species reached 55.6, 35.9, 54.0, and 18.8 μM, respectively). C7 samples also exhibited a three-fold higher phosphatidic acid (PA) content (6.8 μM) and a five-fold higher content (17.3 μM) of lysophospholipids (LPE, LPC, LPS, and LPI) whereas both lysophospholipids and PA remained at their initial levels for 7 days in N7 samples. Taking into consideration the significant phospholipid losses in the controls, the lipid profiling results together with the microbiological data suggest a major role of phospholipase (PLase) C (PLC) in phospholipolysis during cold storage. However, the experimental data also indicate that bacterial sphingomyelinase C, together with PLases PLD and PLA contributed to the degradation of phospholipids present in raw milk as well, and potential contributions from PLB activity cannot be excluded. Altogether, this lipidomics study highlights the beneficial effects of N2 flushing treatment on the quality and safety of raw milk through its ability to effectively hinder phospholipolysis during cold storage.