Effect of Moisture and Heat Treatment of Corn Germ on Oil Quality

Abstract

The changes in the quality of crude corn oil caused by moisture and two different thermal pretreatments (oven heating and steam heating) of wet-milled corn germ were evaluated and compared with those of untreated oil. Increasing the moisture content of the corn germ from 8 to 25% before oil extraction increased the acid value (AV) (3.02-4.01 mg KOH g −1 ), peroxide value (PV) (0.52-1.05 meq kg −1 ), and the red value (7.3-8.7) and decreased the content of total tocopherols by 37% and that of γ-tocopherols by 31%. Oven heating tended to decrease the AV and PV while steam heating significantly increased the total and individual tocopherol contents (P < 0.05). The different moisture contents and thermal pretreatments of corn germ caused no significant differences in the fatty acid composition and the contents of total and individual phytosterols of the crude oils. The γ-tocopherol contents were found to be highly correlated with the red values (the corresponding R 2 reached 0.9977 and 0.9089 for moisture and heat pretreatments, respectively).Keywords Wet-milled corn germ Á Moisture content Á Heat pretreatment Á Oil quality Á Tocopherols Á Color J Am Oil Chem Soc (2018) 95: 383-390.

Influence of processing conditions on some physical characteristics of vegetable oil expressed mechanically from Pentaclethra macrophylla Benth kernels: Response surface approach

“…The color intensity of the oil changed from light yellow to darkish brown as moisture content increased, this is in similar trend with palm oil and sesame oils as reported by Torres and Maestri (). However, increase in heat applications generated increase in color intensity till a certain point before darkening of color samples were physically noticed at high heat applications, an optimum oil color of 7.7 LUR was obtained at 11.7 min and 59 °C heating temperature (Figure ) which is an acceptable level (NIS, 2000), this is in tandem with reports on some edible oils (Xu, Li, Fan, Zheng, & Deng, ) and corn germ oil reported by Zheng et al ().…”

“…The oil expression efficiency of mechanical method of oil separation is affected by the condition of the oleaginous biomaterial and other pretreatment parameters; it has an advantage of low initial and operating costs and expressed oil samples are free of hazardous chemical substances (Bamgboye & Adejumo, ; Ibrahim & Ogunwusi, ).Processing and extraction conditions affect oil characteristics, which can also be dependent on other agronomic factors like climatic conditions, soil composition, ascension, and harvesting time (Compaore et al , ; Fakayode, Ajav, & Akinoso, ; Maestri & Guzman, ; Ogunsina, Owolarafe, & Olatunde, ). Independent variables that influence the quality and quantity of vegetable oil expressed mechanically include processing parameters like heat applications (duration and temperature) (Aktas, Gerçekaslan, & Uzlaşır, ; Raba, Chambre, Copolovici, Moldovan, & Copolovici, ; Rahma, Zekhnini, El‐Alem, & Hatimi, ) and moisture content (Fakayode & Ajav, ; Pornpipat, Hattha, & Tantanawat, ; Sarah, Widyastuti, & Ningsih, ; Udoh, Olayanju, Dairo, & Alonge, ; Zheng et al , ). Literature is very scanty on the effect of variables affecting the quality (yield) and quantity (characteristics) of vegetable oil expressed mechanically from African oil bean kernels (Aremu & Ogunalde, , ).…”

Influence of Prolonged Deep‐Frying Using Various Oils on Volatile Compounds Formation of French Fries Using GC–MS, GC‐O, and Sensory Evaluation

“…The conditions were referred to our previous research (Li et al, 2015). Tocopherol isomers were analyzed using HPLC‐PAD with scanning from 200 to 600 nm according to a modified method (Zheng et al, 2018). The phytosterols were analyzed according to the method adopted by Zhang et al (2020), and the analysis results of tocopherol and phytosterols are shown in Table S1.…”

Chemical Compositions and Oxidative Stabilities of Ginkgo biloba Kernel Oils from Four Cultivated Regions in China

“…Tocopherol isomers were analyzed using HPLC‐PAD with scanning from 200 to 600 nm according to a modified method (Zheng et al, 2018a). Initially, oil samples weighing 0.2 g were dissolved with 2 mL hexane, and the injection volume was 20 μL.…”