Degree

Doctor of Philosophy (PhD)

Department

Food Science and Technology

Document Type

Dissertation

Abstract

Rice bran, a nutrient-rich byproduct of rice milling, has gained interest for its potential health benefits and value-added product development. This outer layer of the rice kernel is composed of carbohydrates, fats, proteins, dietary fiber, vitamins, minerals, and antioxidants. Research indicates that rice bran holds promise for functional food applications and nutraceutical development, with ongoing efforts to maximize its health benefits and improve its stability and nutritional value, including fermentation. However, a key challenge in utilizing rice bran is its susceptibility to rancidity due to its high fat and lipase enzyme activity. This work describes an effort to enhance and stabilize Frontière rice bran using a sous vide solid state fermentation method incorporating two lactic acid bacteria, L. reuteri and L. plantarum. Changes in the compound levels resulting from sous vide fermentation were quantified using normal-phase high-performance liquid chromatography (NP-HPLC) to measure the concentrations of tocopherols, tocotrienols, and gamma oryzanol, while volatile markers were analyzed via solid-phase micro-extraction gas chromatography mass spectroscopy (SPME GC-MS). Overall, the L. reuteri sous vide fermentation for 12 hours was identified as the optimum treatment for rice bran, producing 0.00544±0.00039 mg of alpha tocopherols per 100g of rice bran, a 3.03-fold increase. Additionally, measurement of volatile concentrations showed L. reuteri to have the longest fermentation duration as signaled by acetaldehyde trends, with the main phase of fermentation completed between 4 and 12 hours and a secondary phase extending beyond 24 hours. The nutrient profile of the unfermented Frontière rice bran was calculated using proximate and mineral analyses finding Frontière rice bran to be high in manganese, magnesium, and phosphorus.

Sous vide was also used to stabilize the product without subjecting the rice bran to high heat. This method was shown to be more effective than an oven heating method by microbiological testing, reducing coliforms to low or “Not Detected” levels, even for rice bran fermented after stabilization. The optimized and stabilized rice bran was then formulated into a chocolate nut bar and evaluated via a texture profile analysis and a consumer sensory panel. Overall, the product variations were accepted by the consumer sensory panelists, with improvements noted by 25% of consumers to decrease bitterness and increase sweetness for both the control and fortified chocolate nut bars.

Date

8-18-2026

Committee Chair

King, King M.

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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Available for download on Friday, August 17, 2029

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