The effects of roasting temperatures on the formation of headspace volatile compounds in perilla seed oil

Abstract

Volatile compounds of perilla seed oils roasted at different temperatures (150-190°C) were analyzed by dynamic headspace gas chromatography-mass spectrometry. The headspace volatiles in roasted perilla seed oils (RPSO) were composed of thermally produced flavors and compounds originating from the raw perilla seeds. The roasting temperatures significantly affected the production of thermal reaction flavors. Oils from parilla seeds roasted below 170°C had relatively high concentrations of aldehydes, whereas pyrazines and furans were the predominant volatiles above 170°C. In all of the RPSO, the contents of both perilla aldehyde and perilla ketone remained almost constant and might be used to discriminate perilla seed oils from other roasted vegetable seed oils.Perilla seed [Perilla frutescens (L.) Britt.] is composed of 40-45% (w/w) oil with a high α-linolenic acid (n-3 fatty acid) content (1). Roasted perilla seed oils (RPSO) are widely used as condiment oils in Asian countries, especially in Korea and China, because of their roasted, nutty, and distinctive aromas, reminiscent of perilla aldehyde. Similar to sesame seed oils, RPSO are traditionally tailor-made by roasting, mechanical pressing, and simple refining from the raw perilla seeds. The roasting process may be a critical step for producing perilla seed oils because many aromatic compounds may be produced by the heat treatment that has an effect on the flavor quality of RPSO. Flavor profiles of RPSO are generally changed under different roasting temperatures (2). There have been no detailed reports yet, however, on the volatile components of RPSO. Hence, the objective of the present study was to identify the volatile compounds of RPSO and to investigate the effects of roasting temperature on the production of headspace volatile flavor components of RPSO. MATERIALS AND METHODS Materials.Perilla seeds were obtained from local areas in Korea. Total lipids of perilla seeds extracted with diethyl ether in a Soxhlet apparatus for 12 h were 44.5 % (w/w). Standard chemicals for identification of volatiles in gas chromatography (GC) and mass spectra were purchased from Aldrich Chemical Company (Milwaukee, WI) Sigma Chemical Co. (St. Louis, MO), and Fluka Chemie AG (Buchs, Switzerland). Iso-octane, used as a dilution solvent of standard chemicals was obtained from Fisher Scientific (Norcross, GA).Preparation of RPSO and nonroasted perilla seed oils (NPSO). Perilla seeds were washed and dried to 6.4% (w/w) moisture content prior to roasting. The seeds (400 g) were roasted at 150, 160, 170, 180, and 190°C for 3 min using a continuous and circular monolayer roasting machine (Taewhan Automatic Instrument Co., Seoul, Korea). The roasted seeds were fed into the hopper immediately to minimize heat loss and expelled with a screw-type press at 60 rpm and 500 kg/cm 2 . The barrel temperature of a press during each run was maintained at 120°C. This process produced about 120 to 125 g of oil and cakes in the form of flakes with 0.6-mm thickness. Four replications for RPSO at ea...

Physicochemical and Sensory Properties of Mihalic Cheese

“…[67,68] 3-Methylthiophene is produced via Maillard reaction and known as a major heterocyclic sulfur compound. [69] Previous studies revealed that this compound was found in Chevre style goat, Ezine, and Circassian cheeses. [64−66] However, intensities of diacetyl (buttery), ethyl butyrate (sweet, bubble gum), butyric acid (rancid, cheesy), and hexanoic acid (cheesy, sour) were very high in the cheese.…”

Lexikon der pflanzlichen Fette und Öle

“…Geruchlich aktive Verbindungen in Perillaöl in Abhängigkeit von der Rösttemperatur der Samen vor der Extraktion (Kim et al 2000): …”

Sensory characteristics and consumer acceptability of perilla porridges

“…The roasting process explains these ratings. Prior studies have shown that the more roasting temperature gets higher, the more volatile compounds associated with the flavor of perilla seed oil are produced (27). The NHPP sample, which was made with non-husked perilla seed powder, had higher salty aroma, herbal medicine, burnt aroma, rye bread, and spoiled rice attribute scores compared with the other samples.…”

“…The TPP sample was distinguished from the other samples as having significantly high roasted soy flour, soggy, and soy milk attribute scores but significantly lower paste, fermented rice, sodden, jelly, and flying fish roe attribute scores (p<0.05). Odor/Aroma: Although both RSPO and RWPO samples were oil-based, they had different characteristics that may have been due to unique perilla oil manufacturing processes (3,26,27). The RWPO sample was rated as having relatively high rancid oil, lettuce, perilla leaf, paint, plastic, and sour aroma attribute scores, whereas the RSPO sample showed significantly lower scores for these attributes (p<0.05).…”

“…Although the Chinese panelists use perilla oil as an edible ingredient (27) and consume many types of breakfast porridges (29), they are not only unfamiliar with perilla porridges, but are also rarely exposed to them. Cultural factors related to familiarity and sensitivity acquisition via mere exposure can explain the different number of descriptors generated by Korean and Chinese panel, respectively (30).…”