Acetic acid hexyl ester

A study revealing volatile aroma produced by Pediococcus pentosaceus in dough fermentation.[Pubmed:32994968]

Food Sci Nutr. 2020 Aug 3;8(9):5077-5085.

Pediococcus pentosaceus is important probiotics in Chinese Laomian. Its role in meat and fermented vegetable has been largely demonstrated, but few studies have investigated the role of P. pentosaceus in Chinese Laomian. For this purpose, we simulated Laomian fermentation using Saccharomyces cerevisiae and P. pentosaceus. Volatile aroma was detected by headspace solid-phase microextraction gas-chromatography-mass spectrometry. Real-time fluorescent quantitative polymerase chain reaction was used to determine dynamic growth of S. cerevisiae and P. pentosaceus in fermentation. Extracellular proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Folin-Ciocalteu method was used to detect extracellular protease activity in different pH values. Owing to addition of P. pentosaceus, the types and contents of esters increase, the relative contents of Acetic acid hexyl ester, formic acid octyl ester, and heptanoic acid ethyl ester rise obliviously; especially, the relative content of hexanoic acid ethyl ester was highly correlated with P. pentosaceus by increasing 20.61%. As the gel electrophoresis results display, due to mixed fermentation of S. cerevisiae and P. pentosaceus, the 25k Da and 51k Da proteins expression quantity of P. pentosaceus clearly increased. Under neutral and alkaline culture conditions, the extracellular protease activity of P. pentosaceus is higher. This research benefits to gain insight into the fermentation actions of P. pentosaceus in Chinese Laomian.

Identification of volatile components from oviposition and non-oviposition plants of Gasterophilus pecorum (Diptera: Gasterophilidae).[Pubmed:32978441]

Sci Rep. 2020 Sep 25;10(1):15731.

Oviposition by Gasterophilus pecorum on shoot tips of Stipa caucasica is a key determinant of its severe infection of the reintroduced Przewalski's horse (Equus przewalskii). Volatiles in shoots of grasses on which Przewalski's horse feeds, including S. caucasica at preoviposition, oviposition, and postoviposition stages of G. pecorum, S. caucasica, Stipa orientalis, and Ceratoides latens at the oviposition stage, and S. caucasica in various growth periods, were collected by dynamic headspace adsorption and analyzed by automatic thermal desorption gas chromatography-mass spectrometry. Among five volatiles with highest relative contents under three sets of conditions, caprolactam and 3-hexen-1-ol,(Z)- were common to all samples. Caprolactam was highest in C. latens at oviposition stage of G. pecorum and lowest in S. caucasica at postoviposition stage, and that of 3-hexen-1-ol,(Z)- was lowest in C. latens and highest in S. caucasica at its oviposition stage. Particularly, in S. caucasica during the three oviposition phenological stages of G. pecorum, 3-hexen-1-ol,acetate,(Z)-, 2(5H)-furanone,5-ethyl-, and 3-hexen-1-ol,acetate,(E)- were unique, respectively, to the preoviposition, oviposition, and postoviposition stages; in three plant species during the oviposition stage of G. pecorum, 3-hexen-1-ol,acetate,(Z)-, 3-hexenal, and 1-hexanol were unique to S. orientalis, acetic acid, hexanal, and 2(5H)-furanone,5-ethyl- to S. caucasica, and 1,3,6-octatriene,3,7-dimethyl-, cis-3-hexenyl isovalerate, and Acetic acid hexyl ester to C. latens; in S. caucasica, 2-undecanone,6,10-dimethyl- was unique to the early growth period, acetic acid and 2(5H)-furanone,5-ethyl- to the flourishing growth period, and 3-hexen-1-ol,acetate,(Z)- and 1,3,6-octatriene,3,7-dimethyl- to the late growth period. Furthermore, substances specific to S. orientalis and C. latens were also present in S. caucasica, except at oviposition stage. Our findings will facilitate studies on G. pecorum's adaptation to the arid desert steppe and its future control.

Manipulation of sensory characteristics and volatile compounds in strawberry fruit through the use of isolated wavelengths of light.[Pubmed:32043600]

J Food Sci. 2020 Mar;85(3):771-780.

Consumers consistently note that there is room for improvement in the flavor of commercial strawberries. Fruit flavor and aroma are affected by both genetics and environment. This work tests the hypothesis that sensory quality may be manipulated using postharvest light treatments. Individual detached fruits representing two different cultivars received a 24-hr treatment of 100 micromol m(-2) s(-1) blue LED light while the control was kept in complete darkness. Following treatment, samples were analyzed for flavor volatiles, sugars, acids, firmness, and sensory differences in human trials. Fruits were rated for overall liking, texture, sweetness, sourness, and overall strawberry flavor intensity (OSFI) on the sensory and hedonic versions of the global intensity scale (GIS). A positive treatment effect was observed for "Strawberry Festival" fruit for the overall liking rating. A triangle test revealed a significant treatment effect, as light-treated fruit tested higher in many flavor volatiles including those known to contribute to sweetness in strawberries. Levels of several volatiles were consistently higher in the treated fruit across all four harvests: Acetic acid hexyl ester, butanoic acid octyl ester, methyl isovalerate, and pentanoic acid ethyl ester. The results show that postharvest light treatment can be used to modulate sensory quality of fruit, perhaps offering a means to complement genetic efforts in fruit flavor and aroma improvement. PRACTICAL APPLICATION: The results indicate that it may be possible to increase the sensory quality of strawberry fruits using an inexpensive and noninvasive light treatment. Light may be applied during transport or storage to improve fruit quality. This concept could also be extended into other realms of storage, such as residential and commercial refrigeration, further increasing the quality impact of the approach.