# High Pressure and Pasteurization Effects on Dairy Cream +
## 3 Results and Discussion
### Fatty Acid Analysis  
To our knowledge, this is the first study that reports the changes observed in cream's fatty acid profile after thermal pasteurization and pressurization treatments, upon storage. The GC analysis revealed the presence of twenty-nine FAs (Table S3--available in the Supplementary Materials). The cream samples were essentially rich in saturated, followed by monounsaturated, and a small percentage of polyunsaturated FAs. Raw cream's main fatty acids were palmitic (C16:0, 24.50 \(\pm\) 0.12%), oleic (C18:1c, 20.03 \(\pm\) 0.11%), and myristic (C14:0, 11.25 \(\pm\) 0.07%), similar to what was previously reported (Kal  
hydes/ketones, acids, and lactones. Immediately after thermal and HPP treatments, a new class of compounds, alcohols, was detected on cream samples (Table 3). Alcohols can be produced by the reduction in their corresponding aldehydes and methyl ketones, through the activity of LAB dehydrogenases or by sugar fermentation, which is in accordance with the lower pH measured in these samples [32]. From the 28 th day onwards, thermally treated samples presented higher (\(p\leq 0.05\)) amounts of alcohol compared to HPP samples. Similarly, [PERSON] et al. (2014) studied the effect of thermal pasteurization on skim milk's volatile composition, observing that during refrigerated storage, alcohol concentration increased as a result of the reduction in the corresponding carbonyl compounds [33]. The initial amount of acid compounds in raw cream increased (\(p\leq 0.05\)) immediately after thermal and HPP treatments (Table 3). Throughout the storage, the number of acids on HPP samples remained higher (\(p\leq 0.05\)) than on thermally treated samples. [PERSON] et al. (2015) observed a relevant increase of carboxylic acids in human milk after processing at 400 or 600 MPa for 6 min, which was probably due to the release of short-chain FAs from triglycerides (lipolysis) [34]. Acids can act as precursor molecules for a series of catabolic reactions, which can lead to the production of other flavor compounds such as alcohols, lactones, and methyl ketones [32]. All cream samples presented a similar (\(p>0.05\)) content of aldehydes/ketones after processing compared to the raw cream, except for 600/15 samples, which presented higher levels (\(p\leq 0.05\)) (Table 3). [PERSON] et al. (2006) observed that at 25 \({}^{\circ}\)C, ketone concentration in milk processed under 620 MPa at 1, 3, or 5 min was similar to raw milk [35]. Despite the fact that ketones are naturally present in raw milk, most of them can be formed during heat treatment by \(\beta\)-oxidation of saturated fatty acids or by decarboxylation of \(\beta\)-ketoacids. Furthermore, several authors reported that HPP enhances the oxidation of free FAs, leading to the formation of ketone VOCs [34; 36; 37]. [PERSON] et al. (2006) also observed an increase in aldehyde concentration when milk was processed at 620 MPa, which was possibly due to a higher solubility of oxygen under high pressure, which could enhance the formation of hydroperoxides, resulting in more aldehydes [35]. Aliphatic hydrocarbons were the major VOCs found on cream samples, presenting no regular tendency throughout the storage days under all processing conditions; they were statistically similar (\(p>0.05\)) on both thermal and HPP samples. However, their content was significantly higher on thermally treated samples (\(p\leq 0.05\)). Accordingly, [PERSON] et al.