Food Engineering

Research Overview

Agriculture contributes close to a trillion dollars to the U.S. GDP and provides about 10 percent of employment.  Food accounts for more than 12 percent of household expenditures and the food industry is one of the largest in the U.S.

Detecting, controlling and maintaining food safety and quality are paramount and require efficient processing, storage, and handling along all parts of the food supply chain. Some of our research focuses on the following:

  • Post harvest handling systems, quality measurement and control, traceability
  • Innovative processes to reduce energy, water and other inputs in food processing
  • Food process automation, sensing, control and sanitation for enhanced food safety, microbial and other contaminant detection
  • Food digestion, targeted food properties for enhanced nutrition
  • Microencapsulation of bioactive compounds, controlled release coatings and materials

Click here to see more examples and potential career paths.


Recent Research Results

Food Digestion and Targeted Food Processes

"Effects of freezing, freeze drying and convective drying on in vitro gastric digestion of apples":

Food Engineering UC Davis Biological and Agricultural Engineering
Microphotographs of the samples of apple: a-Raw, b-FN, c-FD and d-CD. 1-SEM and 2-LM of initial apple samples (prior to in vitro digestion). 3-SEM and 4-LM after
180 min of in vitro gastric digestion.

The influence of processing (freezing in liquid, freeze drying, and convective drying) on apples was investigated. After dried apples were re-hydrated, changes in carbohydrate composition, moisture, soluble solids, acidity, total polyphenol content (TPC), and antioxidant activity (AA) of apple samples were measured at different times during digestion.

Food Engineering UC Davis Biological and Agricultural Engineering
Evolution of chemical characteristics of raw and processed apple samples
during in vitro digestion: a-moisture content, b-soluble solids content and c-acidity.

Processing resulted in disruption of the cellular structure during digestion, as observed by scanning electron microscopy, light microscopy, and changes in carbohydrate composition. Moisture content increased (6–11% dmo), while soluble solids (55–78% dmo), acidity (44–72% dmo), total polyphenol content (30–61% dmo), and antioxidant activity (41–87%) decreased in all samples after digestion. Mathematical models (Weibull and exponential models) were used to better evaluate the influence of processing on apple behavior during gastric digestion.

Dalmau, M.E., Bornhorst, G.M., Eim, V., Rosselló, C. and Simal, S., 2017. Effects of freezing, freeze drying and convective drying on in vitro gastric digestion of apples. Food chemistry, 215, pp.7-16.

Food Safety, Microbial Detection, Process Control and Sanitation

Food Safety and Engineering UC Davis Biological and Agricultural Engineering
Representative widefield bioluminescence images of lettuce leaves after exposure to different wash water: (A) leaf surface without soil; (B) leaf surface with soil.

"Enhanced removal of Escherichia coli O157:H7 and Listeria innocua from fresh lettuce leaves using surfactant during simulated washing": Removal of foodborne bacterial pathogens from fresh produce during washing and sanitation process can significantly improve inactivation of the bacteria. Currently, produce wash systems mainly rely on mechanical forces to aid in removal of bacteria attached to the produce surface during washing and sanitation. This study evaluates the potential of surfactants to enhance removal of pathogens from the surface of fresh produce. Influence of three types of commercial food-grade surfactants, including Tween-20, sodium dodecyl sulfate (SDS), and lauric arginate (LAE), on the mechanical removal of pathogenic bacteria and viruses from fresh lettuce leaves in the presence of soil was evaluated...The most effective Escherichia coli O157:H7-lux removal was obtained by washing with 0.1% LAE, followed by 0.1% Tween-20, then 0.1% SDS. The most enhanced detachment of Listeria innocua was achieved by 0.1% LAE, followed by 0.1% SDS, then 0.1% Tween-20...Overall, these results suggest the potential of food grade surfactants to enhance the removal of bacteria particularly foodborne pathogens from the surface of fresh produce.

Huang, K. and Nitin, N., 2017. Enhanced removal of Escherichia coli O157: H7 and Listeria innocua from fresh lettuce leaves using surfactants during simulated washing. Food Control, 79, pp.207-217.

Pulsed Light Decontamination and Disinfection

Food Engineering and Safety UC Davis Biological and Agricultural Engineering
Scanning electron micrographs of A. flavus spores: (A) untreated control cells; (B) cell treated with pulsed light at an intensity of 2.86 W cm−2 for 10 s; (C) cell treated with UV‐C at an intensity of 3.60 mW cm−2 for 10 min; (D) cell treated with 0.525% sodium hypochlorite.

"Simultaneous decontamination and drying of rough rice using combined pulsed light and holding treatment": The objective of this study was to investigate the feasibility of simultaneous disinfection and drying of rough rice using PL and holding treatment. Freshly harvested rice samples were inoculated by Aspergillus flavus (A. flavus) and treated using PL under different intensities and durations followed by holding treatment. The PL treatment under intensity of 1.08 W cm−2 for 21 s led to a reduction of 0.29 log cfu g−1 on the population size of A. flavus spores. After holding treatment, a 5.2 log cfu g−1 reduction was achieved. The corresponding total moisture removal reached 3.3% points. No adverse effect on milling quality was detected after the treatment. The obtained results revealed that the combined PL and holding treatment had good potential for successful application in the rice industry to simultaneously achieve disinfection and drying.


Development of Bioprocessing Strategy to Recover Mild Oligosaccharides

Food Engineering UC Davis Biological and Agricultural Science
Process flow diagram for the integrated process to recover oligosaccharides from bovine colostrum at pilot-scale.

"An integrated bioprocess to recover bovine milk oligosaccharides from colostrum whey permeate":  A major challenge in isolating oligosaccharides from dairy streams is to enrich oligosaccharides while simultaneously reducing the content of simple sugars (mono- and disaccharides) that do not possess the desired prebiotic functions. An integrated approach based on optimized conditions that favor maximum lactose hydrolysis, monosaccharide fermentation and oligosaccharides recovery by nanofiltration was developed. Upon complete lactose hydrolysis and fermentation of the monosaccharides by yeast, nanofiltration of fermented whey permeate from colostrum enabled the recovery of 95% of the oligosaccharides at high purity. While the number of commercially available standards has limited the quantification of only a few sialylated oligosaccharides, the application of both high performance anion-exchange chromatography with pulsed amperometric detection and mass spectrometry provided a complete profile of the final product. Approximately 85% of the oligosaccharides in the final concentrate were sialylated, with the remainder being neutral.

Food Engineering UC Davis Biological and Agriculural Engineering
Effects of operational parameters on monosaccharide fermentation efficiency: reaction time vs. amount of active dry yeast (a); amount of yeast extract vs. amount of active dry yeast (b); amount of active dry yeast vs. reaction time (c).