Spoilage of cereal and sea food ( physical, chemical and biological)
- 1. SPOILAGE OF CEREAL AND SEA FOOD Presented by P Sobhangi Msc industrial microbiology ( 3rd sem)
- 2. INTRODUCTION Spoilage Food spoilage refers to the process in which food deteriorates to the point it is not edible. This can be caused by biological, chemical, or physical changes. Focus on Two Categories: Cereal Spoilage Seafood Spoilage
- 4. CEREAL SPOILAGE Nutritional Importance: Cereals are staple foods, widely consumed globally. Rich in protein (8-15%), carbohydrates (70-75%), fiber, fat, vitamins, and minerals. Spoilage Agents: Molds: Common spoilage organisms due to moisture needs (Aspergillus, Penicillium, Fusarium). Moisture levels (12-13%/aw 0.94-0.97),Optimal pH for molds: 5.5-6.0; bacteria prefer neutral pH (6.5-7.0). Bacteria: Pseudomonas, Bacillus, Lactobacillus, etc. Yeasts: Play smaller roles in cereal spoilage. Fungal : Aspergillus, Penicillium, Fusarium Spoilage Causes: Environmental conditions: moisture, temperature, pH. Pre-harvest contamination from soil, insects, and equipment. Post-harvest mishandling (threshing, winnowing, storage).
- 5. On-field vs. Storage Spoilage: On-field molds attack crops before harvest, especially in humid conditions (Alternaria, Fusarium). Storage molds (Aspergillus, Penicillium) thrive under poor storage conditions. Spoilage Conditions: Environmental fluctuations cause moisture condensation, leading to “hotspots” of mold growth. Insect damage can worsen spoilage by transmitting mold spores. Economic and Safety Impacts: Spoilage causes major economic losses. Molds produce harmful mycotoxins, posing health risks. Future Directions: Improved spoilage prediction models using microbial growth parameters and climate data. Development of rapid detection methods for spoilage organisms.
- 8. CONTROL OF CEREAL SPOILAGE Cultivation Practices: Use well-composted biological amendments to reduce pathogens. Employ safe water for irrigation, proper tillage, crop rotation, and wildlife control to prevent contamination. Harvesting Factors: Timely harvesting and seed treatments can help minimize spoilage risks. Post-harvest Spoilage Control: Manage moisture, temperature, insects, and pests to reduce spoilage risks. Sorting, cleaning, and sanitizing grains before storage is essential. Storage Practices: Proper grain drying technology and storage designs that prevent moisture build-up are critical. Avoid conditions that increase grain moisture absorption. Preservatives and Treatments: Organic acids (acetic, lactic, sorbic, citric, etc.) and propionate or sorbate are common preservatives. Techniques like irradiation and natural antimicrobials are also used. Molds and yeasts may resist some preservatives.
- 9. PRESERVATION: 1. Drying Method: Reduce the moisture content to about 12-14% to inhibit the growth of microorganisms. Effectiveness: Prevents mold, bacteria, and insect infestation. 2.Hermetic Storage Method: Store cereals in airtight containers or bags to create an oxygen- deficient environment. Effectiveness: Limits the growth of aerobic microorganisms and prevents insect activity. Application: Hermetic bags (e.g., PICS bags), metal silos. 3. Fumigation Method: Use of fumigants like phosphine or methyl bromide to kill insects and pests. Effectiveness: Highly effective against insects and pests in stored grains. Application: Commonly used in warehouses and bulk storage facilities. 4. Modified Atmosphere Storage (MAS) Method: Replace the air in the storage with a mixture of gases (e.g., nitrogen, carbon dioxide) to suppress pests and spoilage organisms. Effectiveness: Controls both insects and molds by reducing oxygen levels. Application: Often used in sealed storage containers or silos.
- 11. SEAFOOD SPOILAGE Fish and seafood products are some of the most important protein sources in human nutrition. These products are perishable and, if left unpreserved, spoil rapidly. Some fish products are heavily cured (salted, dried) and shelf stable at ambient temperature. An increasing number of fish products are preserved by low levels of salt, cooling, packaging in modified atmosphere, and/or addition of low levels of preservatives. The microflora of these products is often complex; however, spoilage is mostly caused by microbial action.
- 12. Seafood Overview: Includes finfish, crustaceans (shrimp, lobster, crabs), mollusks (oysters, clams), etc. Rich in protein, varying fat content, low in carbohydrates (except mollusks). Factors Influencing Microbial Composition: Pollution levels, water temperature, and contamination sources. Bacteria like Vibrio, Pseudomonas, Enterococcus, and pathogenic strains (e.g., Vibrio parahaemolyticus). Contamination Sources: Contaminated waters (human/animal waste), handling practices. Pathogens: Salmonella, Vibrio cholera, hepatitis A, Norovirus. Common Seafood Pathogens: Bacteria: Vibrio spp., Listeria monocytogenes, Salmonella. Viruses: Hepatitis A, Norovirus. Parasites: Roundworms, flatworms.
- 13. Health Risks: Foodborne illnesses: Gastroenteritis, severe infections, poisoning. Marine toxins and chemical contamination also pose risks. Hygiene & Quality Control: Heat processing reduces microbial loads. Implement hygiene and sanitation in seafood processing. Use hurdle technology (multiple preservation methods) to control microbial growth. Preventative Measures: Regular monitoring of water quality and contamination. Adopting proper handling, storage, and processing techniques to reduce spoilage.
- 14. Spoilage Causes: Fish spoilage results from autolytic enzymes, oxidation, and microbial growth. Protein hydrolysis occurs when fish are not gutted after catching. Main spoilage bacteria: Gram-negative rods (Pseudomonas, Acinetobacter, Shewanella, Vibrio). Fish Spoilage Process: Bacteria metabolize nitrogen compounds, producing off-odors (ammonia, trimethylamine, hydrogen sulfide). Spoilage results in slime, discoloration, soft texture, and foul odors (fishy, putrid). Spoilage by Storage Condition: Aerobic storage: Dominated by Pseudomonas spp. Vacuum/CO2 storage: Lactic acid bacteria take over, slowing spoilage. Refrigeration & Spoilage: Refrigeration slows spoilage, extending shelf life. Key spoilage bacteria: Shewanella, Aeromonas, Vibrio, Enterobacteriaceae.
- 15. Microbial Spoilage in Seafood Crustaceans Spoilage: Shrimp spoil faster than crabs/lobsters due to post-death harvest. Spoilage bacteria: Pseudomonas, Gram- negative rods. Common signs: odor changes, slime formation, soft texture. Mollusc Spoilage: Lower nitrogen compounds, higher carbohydrates (glycogen 3.5%-5.5%). Spoilage driven by Pseudomonas and Vibrio. Carbohydrates broken down by lactic acid bacteria, causing pH drop and organic acid production.
- 17. CONTROL ON SEA FOOD SPOILAGE Traditional Control Methods: Education and training, facility inspections, and microbiological testing as per ICMSF guidelines. Prevention practices based on HACCP for managing seafood hazards. Processing Facility Design: Seafood processing requires strategic facility design for hygiene. Good Manufacturing Practices (GMP), Good Hygiene Practices (GHP), and HACCP programs ensure product safety by controlling microbial growth and contamination.
- 18. Hurdle Technology for Microbial Control Microbial Hazards in Seafood: Biological, chemical, and physical hazards in seafood can include bacteria, viruses, toxins, and foreign bodies. Main microbial sources: water contamination, human/animal reservoirs, and processing environments. Hurdle Technology: Uses multiple preservation methods (temperature, pH, water activity) to create unfavorable conditions for microbial growth. Prevents contamination by controlling bacteria growth and ensuring safety through cooking and proper storage conditions.
- 19. Hurdles in Marine Products: Key hurdles for preservation include salt, smoke, acids, temperature, and fermentative microorganisms. These are commonly used in products like salted cod, smoked salmon, and marinated foods. Redox potential is used in vacuum-packed products to limit spoilage. Modern Preservation Methods: Innovative methods like high-pressure processing, ultraviolet light, microwave heating, and ozone are being researched for microbial control. These hurdles may affect food's nutritional value or taste, requiring careful balancing. Synergistic Approach: Hurdle technology combines multiple preservation barriers, reducing the need for excessive preservatives while ensuring food safety and quality. Focuses on creating inhospitable environments for microorganisms, targeting their homeostasis and stress responses to prevent growth or survival.
- 20. Thank you