Volatile Profiling of Spirulina Food Supplements

Abstract

Spirulina, a cyanobacterium widely used as a food supplement due to its high nutrient value, contains volatile organic compounds (VOCs). It is crucial to assess the presence of VOCs in commercial spirulina products, as they could influence sensory quality, various processes, and technological aspects. In this study, the volatile profiles of seventeen commercial spirulina food supplements were determined using headspace solid-phase microextraction (HS-SPME), coupled with gas chromatography-mass spectrometry (GC-MS). The identification of volatile compounds was achieved using a workflow that combined data processing with software tools and reference databases, as well as retention indices (RI) and elution order data. A total of 128 VOCs were identified as belonging to chemical groups of alkanes (47.2%), ketones (25.7%), aldehydes (10.9%), alcohols (8.4%), furans (3.7%), alkenes (1.8%), esters (1.1%), pyrazines (0.8%), and other compounds (0.4%). Major volatiles among all samples were hydrocarbons, especially heptadecane and heptadec-8-ene, followed by ketones (i.e., 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one, β-ionone, 2,2,6-trimethylcyclohexan-1-one), aldehydes (i.e., hexanal), and the alcohol oct-1-en-3-ol. Several volatiles were found in spirulina dietary supplements for the first time, including 6,10-dimethylundeca-5,9-dien-2-one (geranylacetone), 6,10,14-trimethylpentadecan-2-one, hept-2-enal, octanal, nonanal, oct-2-en-1-ol, heptan-1-ol, nonan-1-ol, tetradec-9-en-1-ol, 4,4-dimethylcyclohex-2-en-1-ol, 2,6-diethylpyrazine, and 1-(2,5-dimethylfuran-3-yl) ethanone. The methodology used for VOC analysis ensured high accuracy, reliability, and confidence in compound identification. Results reveal a wide variety of volatiles in commercial spirulina products, with numerous newly discovered compounds, prompting further research on sensory quality and production methods.

Influence of Drying and Storage Conditions on the Volatile Organic Compounds Profile of Spirulina Platensis

“…The results are presented in Table S1, which includes all identified analytes along with the total ion chromatogram (TIC) area of the individual chromatographic peaks. The chemical classes of the detected VOCs mainly included hydrocarbons, ketones, aldehydes, alcohols, pyrazines, furans, esters, and organic acids, which is comparable to the results of similar studies found in the literature [25,42]. Figure 1 shows the formation pathways of the main VOCs in Spirulina.…”

“…The major aldehyde detected in the SP samples was hexanal, a volatile compound known for its characteristic grassy odor. This observation is in line with previous studies regarding SP [25,42,47] and other microalgae species [50]. Among the fresh samples, those subjected to air-drying exhibited higher levels of hexanal, indicating heightened oxidative stress on the lipids due to increased air contact.…”

“…Pyrazines contribute to nutty and/or roasted notes and are formed through the Maillard reaction or fermentation processes occurring in matrices containing amino acids and sugars. Several pyrazines were identified in the SP samples, in line with previous studies [25,42,47]. Their content was higher in the heat-treated samples, particularly in the stored samples.…”

“…These alcohols were found in the same sample, where the corresponding aldehydes were detected. Another amino acid-derived volatile compound is benzaldehyde, which is derived from the degradation of phenylalanine together with its corresponding alcohol (benzyl alcohol) [25]. It was detected only in the stored samples and in higher quantities in the OD samples.…”

“…For example, a higher CO 2 concentration in cultures of SP leads to an increase in the carbohydrate content and a decrease in proteins and pigments [23], while nitrogen deficiency usually leads to an increase in the fatty acid content [24]. Microalgae adapt to these factors by altering their metabolism, consequently modifying the profile of the volatile organic compounds (VOCs) produced during their growth [25]. VOCs are secondary metabolites produced by cyanobacteria and are easily released into the atmosphere owing to their low molecular weight and high vapor pressure.…”