Continuous decontamination of cumin seed by non-contact induction heating technology: Assessment of microbial load and quality changes

Edris Rahmati; Mohammad Hadi Khoshtaghaza; Ahmad Banakar; Mohammad-Taghi Ebadi; Zohreh Hamidi-Esfahani

doi:10.1016/j.heliyon.2024.e25504

Continuous decontamination of cumin seed by non-contact induction heating technology: Assessment of microbial load and quality changes

Heliyon. 2024 Feb 4;10(4):e25504. doi: 10.1016/j.heliyon.2024.e25504. eCollection 2024 Feb 29.

Authors

Edris Rahmati¹, Mohammad Hadi Khoshtaghaza¹, Ahmad Banakar¹, Mohammad-Taghi Ebadi², Zohreh Hamidi-Esfahani³

Affiliations

¹ Department of Biosystems Engineering, Tarbiat Modares University, Tehran, Iran.
² Department of Horticultural Sciences, Tarbiat Modares University, Tehran, Iran.
³ Department of Food Science and Technology, Tarbiat Modares University, Tehran, Iran.

Abstract

Over the past few decades, the demand for high-quality food has increased steadily. Therefore, it is essential to develop innovative technologies that effectively reduce microbial load while minimizing any negative effect on the quality of spices. The objective of this study was to determine the efficacy of a self-designed non-contact induction heating system using contaminated cumin seeds. The non-contact induction heating decontamination process was performed at different temperatures of 115, 135 and 155°C and durations (45, 60 and 75 s) through continuous process (screw conveyor) in Pyrex cylinder chamber. Various parameters including microbial load, color characteristics, essential oil content, surface morphology, sample temperature, and energy consumption were analyzed as dependent variables in the study. The results showed that the treatment combination (155°C - 60 s) reduced the aerobic plate count from 6.21 to 2.97 CFU/g. Mold, yeast and coliforms in the treatment combination (155°C-45 s) were also reduced by 3.26 and 3.6 CFU/g, respectively. The total color difference of the samples increased due to the degradation and alteration of pigments at high temperatures. However, no statistically significant disparity in essential oil content was observed between the treatment groups and the control group. The quantities of essential oil components in the cumin seeds were determined to align with the ISO standard, with the primary constituents identified as follows: Terpinen-7-al γ (38.98%), Cumin aldehyde (20.75%), γ-Terpinene (18.81%), β-Pinene (13.66%), and p-Cymene (6.2%). In summary, non-contact induction heating system shows promise as an effective technology for surface decontamination of spices. The acquired findings contribute to a deeper understanding of the impact of the induction heating process on both the microbial contamination levels and the quality attributes of cumin seeds. This scientific knowledge serves as a foundational framework for the prospective adoption and integration of this technology on a larger industrial scale.

Keywords: Decontamination; Essential oil; Induction heating; Microbial load; Spices.