About

Dr. Alejandro Castillo is an associate professor in the Department of Animal Science at Texas A&M University and serves as Chair of the Graduate Faculty of Food Science. His research interests include developing control measures to minimize and reduce pathogens in fresh and fresh-cut food products, bacterial reduction on beef and pork products, and fresh produce through sanitizing rinses. He also investigates the use of electron beam irradiation for food safety purposes. Dr. Castillo has published numerous articles in peer-reviewed journals, authored or co-authored six book chapters, and has published two books as an editor. He teaches graduate courses in Microbiology of Foods and co-teaches the HACCP stacked course. Additionally, he has served on the Editorial Board for the Journal of Food Protection and was the Texas A&M representative on the Board of Directors for the National Alliance for Food Safety and Security until 2010. He is an active member of the International Association for Food Protection, the Mexico Association for Food Protection, and the Institute of Food Technologists.

Research topics

• Composite material
• Materials science
• Nanotechnology
• Chemistry
• Ecology
• Engineering
• Biology
• Chemical engineering
• Biochemical engineering
• Chemical physics
• Organic chemistry

Selected publications

• Simulating <i>Listeria monocytogenes</i> Cross‐Contamination of Fresh Avocado in a Dry Pack Line: A Hybrid Approach to Food Safety

  Journal of Food Process Engineering · 2025-10-01

  articleOpen access

  ABSTRACT This study addresses the urgent need for simulation‐based tools that evaluate corrective actions against microbial cross‐contamination in food packing facilities. It presents a novel Food Safety Agent‐Based Simulation (FS‐ABS) that integrates predictive microbiology with discrete event simulation (DES) to track and predict Listeria monocytogenes behavior along a post‐harvest Hass avocado dry processing line. The model combines the operational efficiency of DES with the biological realism of agent‐based modeling, enabling a comprehensive understanding of how L. monocytogenes spreads in complex processing environments. The objectives of this study were threefold: (1) to track and predict microbial cross‐contamination in the avocado dry processing line; (2) to integrate microbiological interactions with supply chain logistics; and (3) to enhance food safety by providing actionable insights for cross‐contamination risk mitigation. Developed in NetLogo, the simulation treats avocados as mobile agents moving across a grid‐based facility, each carrying attributes like contamination levels and transfer probabilities. This approach models both logistical flow and microbial dynamics, offering insights into how contamination propagates and how interventions might contain it. Validation with real‐world data showed that cross‐contamination remains limited at low initial loads (0.1–1.5 log CFU) but increases sharply beyond a 3.0 log CFU threshold—highlighting a tipping point where control measures become ineffective. Scenario testing revealed that increasing sampling frequency and sample size improves contamination detection and reduces variability. The model emphasizes the importance of early intervention, frequent sanitation, and strategic sampling in mitigating contamination risks. This hybrid tool provides a robust decision‐support framework for improving operational integrity and food safety in avocado packing facilities.

  PublisherOA PDFDOI

• Bioinspired Superhydrophobic Nanocoating Based on Polydopamine and Nanodiamonds to Mitigate Bacterial Attachment to Polyvinyl Chloride Surfaces in Food Industry Environments

  Industrial & Engineering Chemistry Research · 2024-03-27 · 16 citations

  articleOpen access

  Typhimurium cells that were able to adsorb onto PVC surfaces over a 24 h period. The use of this fluorine-free superhydrophobic coating on PVC equipment, such as conveyor belts within food production facilities, may help to mitigate bacterial cross-contamination and curb the spread of foodborne illnesses.

  PublisherOA PDFDOI

• Polymeric Coatings with Electrolyzed Acidic Water: A Novel Approach to Extending Egg Shelf Life and Quality

  Polymers · 2024-12-31 · 2 citations

  articleOpen access

  Electrolyzed acidic water (EAW) contains hypochlorous acid as its active compound, which is a potent antimicrobial. It was encapsulated in polymeric coatings and applied to the surface of eggs. The antimicrobial activity and the ability to extend the shelf life of eggs at ambient temperature for 45 days were evaluated, by physical, microbiological, and sensory analyses. The analysis also included the evaluation of mechanical, thermal, and crystallinity properties and the interaction between the coating components and the eggshell. The results showed that eggs from young, middle-aged, and adult hens, encapsulated and coated with EAW, hydroxypropyl methylcellulose, polyvinyl alcohol, and chitosan, gained resistance and a glossy appearance. The thickness of the coating was 2.9 µm for young and adult hens' eggs and 2.60 µm for those of old hens, as observed by SEM. Shelf life was extended to 45 days under refrigeration and more than 30 days at ambient temperature. Coated eggs were acceptable for 85% of the panelists compared to 57% acceptance of non-coated eggs. The encapsulation and coating with EAW as an antimicrobial agent improved the surface protection of commercial eggs, reduced albumen liquefaction, and maintained quality by acting as a barrier against air, thereby preserving sensory characteristics.

  PublisherOA PDFDOI

• Factors Affecting Growth and Survival of Salmonella in Onion Extracts and Onion Bulbs

  Foods · 2024-12-24 · 3 citations

  articleOpen accessSenior authorCorresponding

  This study investigated the survival and growth of Salmonella in onion extracts and bulbs. The inhibition or retardation of Salmonella growth by extracts of red, white, and yellow onions was tested against the onion germplasm and exposure to different light spectra during curing. Separately, survival of Salmonella Newport was tested on red, white, and yellow onion bulbs on the external and internal onion layers with a syringe and needle. Onions exposed to blue, red, and white LED light during curing produced extracts with variable antimicrobial effects (p &lt; 0.05), with those exposed to blue light showing the strongest inhibitory effect on red and white onions only. In survival studies, Salmonella inoculated on the outer scale was reduced by 1.2, &gt;2.7, and &gt;2.4 logs on red, white, and yellow onions, respectively, within 3 days, whereas it grew by 2.4, 2.6, and 2.8 logs inside red, white, and yellow onion bulbs, respectively, over 18 days. In separate trials, the outer layer again did not support the survival of Salmonella Newport. The aw increased significantly from 0.51 to 0.58 in the outer scales and 0.96 to 0.98 for the fourth inner scales. Despite being rich in antimicrobial polyphenols, tissue integrity and water content may still promote Salmonella growth in onions.

  PublisherOA PDFDOI

• Factors Affecting Growth and Survival of &lt;em&gt;Salmonella &lt;/em&gt;in Onion Extracts and Onion Bulbs

  Preprints.org · 2024-11-15 · 1 citations

  preprintOpen accessSenior author

  This study investigated the survival and growth of Salmonella in onion extracts and bulbs. Extracts of an array of onion varieties and germplasms were used to evaluate their ability to retard or inhibit Salmonella growth and the antimicrobial activity of extracts prepared from onions that were subjected to different types of light during curing. Separately, the survival of internalized and non-internalized Salmonella enterica ser. Newport was tested in red, white, and yellow onions by inoculating onion bulbs on the external and internal onion layers and by internalizing Salmonella using a syringe and needle to inject the inoculum inside the bulb. The inoculated onions were stored at room temperature and collecting samples at intervals during storage. Results showed that the varied lighting used for postharvest stimulation resulted in extracts with different antimicrobial effects (P &amp;lt; 0.05). Extracts from red and white onions treated with blue light inhibited Salmonella growth. Extracts from onions treated with white light revealed slow and fast growth of Salmonella in red and yellow, respectively. Of the extracts from the various germplasms, only one corresponding to red onion, inhibited Salmonella growth, whereas the rest showed varying levels of growth retardation (P &amp;lt; 0.05). In survival studies, Salmonella inoculated on the outer layer was reduced by 1.2, &amp;gt; 2.7, and &amp;gt; 2.4 log cycles on red, white, and yellow onions, respectively within 3 days of storage. In the inner layers, Salmonella grew by 2.4, 2.6, and 2.8 log cycles of red, white, and yellow onions re-spectively, over 18-d storage. In separate trials, the outer layer again did not support the survival of Salmonella Newport. While the inner scales on red onion did not allow growth of Salmonella Newport, those of white and yellow onions allowed growth during the first 3 days of storage, followed by reduction to nondetectable levels. Although the antimicrobial effect of onions is attributed mainly to the polyphenols, factors such as tissue integrity or water content in internal tissues may hinder the deleterious effects of poly-phenols against Salmonella.

  PublisherDOI

• Mechanism of Isoniazid‐Induced Hepatotoxicity: Academic Case.

  International Journal of Medical Science and Clinical Research Studies · 2024-06-17

  articleOpen access

  Isoniazid is used to treat or prophylaxis tuberculosis; However, its use may be associated with adverse liver reactions. Clinically overt hepatitis occurs in 0.5%-1% of patients receiving isoniazid as monotherapy. This clinical case reported allows the academy to always verify and monitor liver function in those who have medications that cause damage to liver cells.

  PublisherOA PDFDOI

• Superhydrophobic coatings reduce human bacterial foodborne pathogen attachment to woods used in fresh produce harvest and postharvest packing

  Food Microbiology · 2024-06-21 · 1 citations

  article
  PublisherDOI

• Phyllosphere Bacterial Communities in Spinach Are Influenced by Soil Nitrogen Availability

  Phytobiomes Journal · 2024-11-15 · 2 citations

  articleOpen access

  Nitrogen is an essential macronutrient for the growth and development of plants. For spinach, as for most crops, nitrogen-based fertilizers are used to improve productivity and quality. Although the significance of the soil microbiome in the inorganic nitrogen cycle is well recognized, soil nitrogen's impact on phyllosphere bacterial communities remains unclear. This study investigated changes in the community composition and diversity of bacteria residing on spinach leaves cultivated in soils with varying nitrogen levels. Sixty-eight spinach samples were processed using culture-dependent and -independent methods to evaluate phyllosphere-associated bacterial communities. In culture-dependent methods, populations of mesophiles, psychrotrophs, coliforms, and lactic acid bacteria were quantified by plate counts using appropriate culture media. In culture-independent methods, bacteria were determined by amplicon sequencing based on the V3-V4 region of the bacterial 16S rRNA gene. Counts of mesophiles, psychrotrophs, coliforms, and lactic acid bacteria on low-nitrogen soil-grown spinach were 7.4, 7.1, 6.9, and 5.5 log CFU/g, respectively, whereas high-nitrogen soil-grown spinach showed counts of 7.5, 7.0, 7.0, and 5.7 log CFU/g. These counts did not differ significantly according to the nitrogen levels used for spinach cultivation ( P &gt; 0.05). Amplicon sequencing, however, revealed differences in relative abundance between different taxa levels and soil nitrogen levels. The relative abundance of Erwiniaceae and Planococcaceae was higher in high-nitrogen soil-grown spinach. The relative abundance of Pseudomonadaceae, Enterobacteriaceae, and Rhizobiaceae was higher in low-nitrogen soil-grown spinach. Soil nitrogen content significantly affected spinach phyllosphere microbiome beta diversity. Our results suggest that the bacterial communities of the spinach phyllosphere are influenced by soil nitrogen content. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

  PublisherDOI

• Edible nano-encapsulated cinnamon essential oil hybrid wax coatings for enhancing apple safety against food borne pathogens

  Current Research in Food Science · 2024-01-01 · 31 citations

  articleOpen access

  Post-harvest losses of fruits due to decay and concerns regarding microbial food safety are significant within the produce processing industry. Additionally, maintaining the quality of exported commodities to distant countries continues to pose a challenge. To address these issues, the application of bioactive compounds, such as essential oils, has gained recognition as a means to extend shelf life by acting as antimicrobials. Herein, we have undertaken an innovative approach by nano-encapsulating cinnamon-bark essential oil using whey protein concentrate and imbibing nano-encapsulates into food-grade wax commonly applied on produce surfaces. We have comprehensively examined the physical, chemical, and antimicrobial properties of this hybrid wax to evaluate its efficacy in combatting the various foodborne pathogens that frequently trouble producers and handlers in the post-harvest processing industry. The coatings as applied demonstrated a static contact angle of 85 ± 1.6°, and advancing and receding contact angles of 90 ± 1.1° and 53.0 ± 1.6°, respectively, resembling the wetting properties of natural waxes on apples. Nanoencapsulation significantly delayed the release of essential oil, increasing the half-life by 61 h compared to its unencapsulated counterparts. This delay correlated with statistically significant reductions (p = 0.05) in bacterial populations providing both immediate and delayed (up to 72 h) antibacterial effects as well as expanded fungal growth inhibition zones compared to existing wax technologies, demonstrating promising applicability for high-quality fruit storage and export. The utilization of this advanced produce wax coating technology offers considerable potential for bolstering food safety and providing enhanced protection against bacteria and fungi for produce commodities.

  PublisherDOI

• Bioactive Peptides and Protein Hydrolysates Used in Meat and Meat Products’ Preservation─A Review

  ACS Food Science & Technology · 2024-04-17 · 21 citations

  articleOpen access

  Meat is highly perishable due to its composition and susceptibility to microbial growth and enzymatic degradation. Preservation methods are necessary to extend its shelf life, allowing for longer storage, transportation, and distribution without compromising quality or safety. With increasing consumer demand for natural, minimally processed foods and concerns about synthetic additives, there is a growing need for preservation alternatives, including packaging, which align with these preferences. Natural preservation methods, such as those utilizing peptides and protein hydrolysates, offer a solution that meets consumer demands and industry requirements. This review highlights the significance of isolating peptides and protein hydrolysates with antioxidant and antimicrobial properties for application alone or combined with edible films in meat and meat products. Studies have demonstrated that these bioactive compounds effectively inhibit lipid oxidation and microbial proliferation as viable alternatives to synthetic preservatives without affecting meat’s quality and sensory characteristics. The future application of these natural preservation alternatives holds considerable promise in the food industry. However, overcoming hurdles such as scaling production and ensuring stability are crucial. Interdisciplinary collaborations, technological advancements, and continued research efforts are essential. In particular, artificial intelligence may be the solution to problems commonly encountered when obtaining bioactive peptides and protein hydrolysates, enhancing the efficiency of identifying novel bioactive compounds. Nonetheless, adopting peptides and protein hydrolysates as natural preservatives represents a significant step toward improving food quality and safety while meeting consumer preferences for more natural products.

  PublisherOA PDFDOI

Frequent coauthors

• T. Matthew Taylor

  30 shared

• L.M. Lucia

  Texas A&M University

  28 shared

• Luis Cisneros‐Zevallos

  Texas A&M University

  23 shared

• Mustafa Akbulut

  Texas A&M University

  20 shared

• Nanci Edid Martínez-Gonzáles

  Universidad de Guadalajara

  18 shared

• G.R. Acuff

  Texas A&M University

  18 shared

• E. Cabrera-Díaz

  Universidad de Guadalajara

  14 shared

• Yagmur Yegin

  Massachusetts Institute of Technology

  13 shared

Education

• B.S., Biology and Pharmacy

  University of Guadalajara, Mexico

• Other, Sanitary Microbiology

  University of Guadalajara, Mexico

• M.S., Food Microbiology and Hygiene

  University of Guadalajara, Mexico

• Ph.D., Food Science and Technology

  Texas A&M University