Brazilian aromatic rice (IAC 500): volatile, odor-active, and bioactive compounds, chemical characterization, effect of planting time and storage

Author(s)

Láisa Gomes Dias

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2022-03-25

Examining board members

Neura Bragagnolo; Priscila Zaczuk Bassinello; Cinthia Baú Betim Cazarin; Selma Bergara Almeida

• Advisor: Neura Bragagnolo; Lilian Regina Barros Mariutti

Abstract

IAC 500 rice is a Brazilian aromatic cultivar, developed for cultivation in the State of São Paulo - Brazil. With no data in the literature, this study sought to investigate the IAC 500 rice in terms of its proximate composition, bioactive compounds and volatile compounds at different planting and storage times, compared to the non-aromatic cultivar IAC 2157. Initially, the optimization of the extraction of volatile compounds was performed in rice by solid phase microextraction (SPME). The extraction parameters, sample mass and incubation temperature were optimized by a central composite rotational design (CCRD). In addition to determining the incubation time of the samples and fiber exposure in the headspace (HS). This study provides literature, with an optimized method of extracting volatile compounds for rice by HS-SPME and gas chromatography, coupled with mass spectrometry (GC-MS), in addition to the volatile profile of 12 other commercial cultivars, with 152 volatile compounds being identified amongst them. Then, the analysis of volatile compounds of the cultivar IAC 500 was carried out, and the identification of the compounds that were odor-active, by using gas chromatography-olfactometry (GC-O) analysis. For this, three steps were carried out: (i) the sensory panel was selected and designed, (ii) the aromatic notes of cooked IAC 500 were described, and (iii) GC-O was performed by the Osme method. The compound 2-acetyl-1-pyrroline (2AP) was considered the key compound responsible for the aroma of the IAC 500 variety, with an intensity of 9.8 on a 10 cm scale. It was described as having the odors of popcorn, extruded corn, grain and roasted chicken. Following, the characterization of the aromatic rice IAC 500 was carried out in terms of centesimal composition, amylose content, fatty acid composition, vitamin E, glycemic and insulinemic response. Also, the influence of the planting month on the levels of minerals, phytosterols and free phenolic compounds, was evaluated, and compared to the cultivar IAC 2157. This study demonstrated, that combined with the quality of aroma, the cultivar IAC 500 had higher nutritional quality, with higher levels of ash, proteins, lipids, unsaturated fatty acids and ?-tocopherol. IAC 500 also had a lower insulin requirement for blood glucose control after consumption, compared to non-aromatic rice. Finally, the analysis of volatile compounds in aromatic and non-aromatic rice, was performed according to the planting times, as well as the identification of the volatile compounds, which were responsible for the discrimination of cultivars. The behavior of the 2AP compound during storage as paddy rice and milled rice, under different conditions was also evaluated. Results showed differences between the volatile profile of cultivars, indicating the 2AP compound, as a discriminant between aromatic and non-aromatic rice. However, it was not possible to discriminate the volatile profile of the cultivars between the different planting times. A trend of reduction in the 2AP compound was observed in both storages, which can be delayed according to the conditions under which the rice is stored. The data obtained in this thesis is important to the scientific community and to rice growers, because it contains information characterizing the Brazilian aromatic rice cultivar IAC 500, information which has never been reported before (AU)

• FAPESP's process: 17/25467-0 - Do edaphoclimatic conditions affect volatile and bioactive compounds in aromatic rice?
• Grantee: Láisa Gomes Dias
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)