Reza Tahergorabi

Effect of gamma radiation on the quality and shelf life of refrigerated rainbow trout (Oncorhynchus mykiss) fillets.

The effect of gamma radiation (0, 1, 3, and 5 kGy) on the shelf life of farmed rainbow trout (Oncorhynchus mykiss) fillets that were treated with sodium acetate and vacuum packaged and subsequently stored under refrigeration was studied by measuring microbiological, chemical, and organoleptic changes. Radiation affected populations of bacteria, namely, H2S-producing bacteria and Enterobacteriaceae (P < 0.05). Initial total viable counts of the control samples were ca. 4.41 log CFU/g, whereas the respective counts in samples irradiated at 1, 3, and 5 kGy were 3.08, 1.46, and < or = 1 log CFU/g at day 1 of refrigerated storage. The maximum count of Enterobacteriaceae reached 2.29 and 1.45 log CFU/g at the end of storage for 1 and 3 kGy, respectively, but at a 5-kGy dose no growth of Enterobacteriaceae was observed. Of the biochemical indicators, thiobarbituric acid values for irradiated trout were higher than for nonirradiated fish (P < 0.05). Sensory evaluation (taste) showed a reasonable and good correlation with bacterial populations with storage time. The results revealed that radiation at a high dose (5 kGy) might induce lipid and protein oxidation, although the growth of microorganisms was inhibited. Therefore, radiation at a low dose (3 kGy) could be used to control the microbial and safety biochemical indices of O. mykiss for up to 4 weeks at refrigerator temperature without adverse effects on quality and acceptability.

Isoelectric Solubilization/Precipitation as a Means To Recover Protein Isolate from Striped Bass (Morone saxatilis) and Its Physicochemical Properties in a Nutraceutical Seafood Product

Excessive dietary intake of Na (i.e., NaCl) contributes to hypertension, which is a major risk factor for cardiovascular disease. Normally, NaOH and HCl are used to dissolve and precipitate, respectively, fish muscle proteins in isoelectric solubilization/precipitation (ISP), therefore contributing to increased Na content in the recovered fish protein isolates (FPI). Substitution of NaOH with KOH may decrease the Na content in FPI and, thus, allow development of reduced-Na seafood products. In this study, FPI was recovered with ISP using NaOH or KOH. In order to develop a nutraceutical seafood product, the FPI was extracted with NaCl or KCl-based salt substitute and subjected to cold- or heat-gelation. In addition, standard nutraceutical additives (ω-3 fatty acids-rich oil and dietary fiber) along with titanium dioxide (TiO2) were added to FPI. Color, texture, dynamic rheology, Na and K content, and lipid oxidation of the FPI gels were compared to commercial Alaska pollock surimi gels. FPI gels had greater (p < 0.05) whiteness, good color properties (L*a*b*), and generally better textural properties when compared to surimi gels. Although the ISP-recovered FPI and surimi developed similar final gel elasticity, the proteins in FPI and surimi had different gelation pattern. A reduction (p < 0.05) of Na content and simultaneous increase (p < 0.05) in K content of FPI gels was achieved by the substitution of NaOH with KOH during ISP and NaCl with the KCl-based salt substitute during formulation of the FPI paste. Although cooking and addition of NaCl during formulation of the FPI paste increased (p < 0.05) lipid oxidation in FPI gels, TBARS values were much below rancidity levels. These results indicate that KOH can replace NaOH to recover FPI from whole gutted fish for subsequent development of nutraceutical seafood products tailored for reduction of diet-driven cardiovascular disease.

Antibacterial and Antioxidant Activities of Essential Oils from Artemisia herba-alba Asso., Pelargonium capitatum radens and Laurus nobilis L.

Essential oils are natural antimicrobials that have the potential to provide a safer alternative to synthetic antimicrobials currently used in the food industry. Therefore, the aim of this study was to evaluate the antimicrobial and antioxidant activities of essential oils from white wormwood, rose-scented geranium and bay laurel against Salmonella typhimurium and Escherichia coli O157:H7 on fresh produce and to examine consumer acceptability of fresh produce treated with these essential oils. Our results showed that essential oil derived from rose-scented geranium exhibited the most effective antimicrobial activity at the same and similar minimum inhibition concentration levels (0.4%, v/v and 0.4% and 0.5%, v/v) respectively against Salmonella typhimurium and Escherichia coli O157:H7. All three essential oils showed antioxidant properties, with the highest activity occurring in bay laurel essential oil. In a sensory test, tomatoes, cantaloupe and spinach sprayed with 0.4% rose-scented geranium essential oil received higher scores by panelists. In conclusion, rose-scented geranium essential oil could be developed into a natural antimicrobial to prevent contamination of Salmonella typhimurium and Escherichia coli O157:H7 in fresh produce, plus this oil would provide additional health benefits due to the antioxidant properties of its residue.

Impact of Sweet Potato Starch-Based Nanocomposite Films Activated With Thyme Essential Oil on the Shelf-Life of Baby Spinach Leaves

Salmonella Typhimurium (S. Typhi) and Escherichia coli (E. coli) have been responsible for an increasing number of outbreaks linked to fresh produce, such as baby spinach leaves, in the last two decades. More recently, antimicrobial biodegradable packaging systems have been attracting much attention in the food packaging industry as eco-friendly alternatives to conventional plastic packaging. The objective of this study was to evaluate the effect of antibacterial nanocomposite films on inoculated spinach leaves and on the sensory properties of these leaves during eight days of refrigerated storage. In this study, an antibacterial film comprised of sweet potato starch (SPS), montmorillonite (MMT) nanoclays and thyme essential oil (TEO) as a natural antimicrobial agent was developed. Our results showed that the incorporation of TEO in the film significantly (p < 0.05) reduced the population of E. coli and S. Typhi on fresh baby spinach leaves to below detectable levels within five days, whereas the control samples without essential oil maintained approximately 4.5 Log colony forming unit (CFU)/g. The sensory scores for spinach samples wrapped in films containing TEO were higher than those of the control. This study thus suggests that TEO has the potential to be directly incorporated into a SPS film to prepare antimicrobial nanocomposite films for food packaging applications.

Isoelectric Solubilization/Precipitation as a Means to Recover Protein and Lipids from Seafood By-products

Fish processing by-products (frames, heads, viscera, etc.) typically account for 60–70 % of the total fish weight after industrial filleting. This amount of by-products contains highly nutritious fish muscle proteins and fish lipids rich in heart-friendly omega-3 fatty acids. The proteins and lipids could be recovered and subsequently used in the development of human food products and dietary supplements. This chapter gives an overview of a process called isoelectric solubilization/precipitation (ISP). ISP allows the efficient recovery of proteins and lipids and, therefore, has the potential to add revenue for seafood processors and also to reduce environmental pollution due to the disposal of seafood processing by-products. The commercialization of ISP has been initiated and, likely, the multifold benefits, including both economic and environmental, are forthcoming. ISP is also briefly discussed at the pilot and industrial scales. Finally, alternative applications of the recovered proteins and lipids, as well as the future market for these novel products, are reviewed.

Proteins, Peptides, and Amino Acids

Proteins play a central role in biological systems. Traditionally, milk, meats (including poultry and fish), eggs, cereals, legumes, and oilseeds have been the major sources of food proteins. However, because of the burgeoning world population, nontraditional sources of proteins for human nutrition need to be developed to meet future demands. Therefore this chapter discusses the functional and nutritional value of food proteins, proteins, and amino acids, followed by a discussion of the emerging technologies for food processing that may affect them. This chapter also sheds light on new techniques to address protein recovery from different sources. Finally, the sensory characteristics of food proteins are reviewed.

Effect of Bay (Laurus nobilis L.) Essential Oil on Surimi Gels Nutritionally Enhanced with Salmon and Flaxseed Oils

ABSTRACT Bay essential oil (BEO) at 0.5 and 1 g/100 g was added to surimi gels fortified with omega (ω)-3 rich oils. Although the fortification resulted in increased (P < 0.05) susceptibility of surimi to lipid oxidation, 0.5 g/100 g BEO significantly reduced TBARS (P < 0.05). Addition of ω-3 rich oil or BEO improved the texture. Color values of the surimi seafood were improved particularly when BEO was added. Sensory properties, water activity, and pH values were generally within the acceptable range. These results suggest that the incorporation of BEO may allow food manufacturers to nutritionally enhance surimi seafood with beneficial ω-3 rich oils.

Application of a Surimi-Based Coating to Improve the Quality Attributes of Shrimp during Refrigerated Storage

Shrimp is a popular seafood throughout the world. However, shrimp is highly perishable due to biochemical, microbiological, or physical changes during postmortem storage. In this study, the effect of a surimi-based coating with and without montmorillonite (MMT) nanoclay on shrimp quality was evaluated during eight days of refrigerator storage. Use of a surimi-based coating resulted in reductions of aerobic plate counts (APC) up to 2 log units. The combined effect of the MMT and coating was observed. Surimi-based coating with MMT resulted in lower APC (p < 0.05) toward the end of storage. The application of surimi-based coating with MMT to the shrimp samples improved sensory quality and delayed lipid oxidation and color deterioration during storage time. In general, better texture was observed when coating was applied either with or without MMT. This study suggests that surimi-based coating may improve the quality of shrimp during refrigerated storage.

Conventional macro- and micromolecules separation

The second step for the recovery of valuable compounds from food wastes is macro- and micromolecules separation. The objective of the current chapter is to present different technologies (e.g. alcohol precipitation, ultrafiltration, isoelectric solubilization/precipitation, and extrusion), which have been implemented for this purpose. For instance, solutes are precipitated in the presence of an antisolvent agent, even if they exist in very low concentrations within the feedstock. In addition, the solubility of proteins or lipids could be reduced when pH value turns to their isoelectric point, causing their precipitation. On the other hand, ultrafiltration is a pressure-driven membrane separation technology, which is basically used to separate macro- and micromolecules based on their size. Extrusion is a process using shear energy and heating in order to modify (physically or chemically) the physicochemical properties of macromolecules (polysaccharides, dietary fibers, or proteins) and micromolecules (sugars, polyphenols, vitamins, or minerals). This ability has also been used in particular applications for compound recovery from food wastes.

Nutraceutical Egg Products

Healthy diet plays a prominent role in enhancing the quality of human life. Among the different food products delivering essential nutrients to the body, an egg as a staple food in many cultures has a special place. It is a balanced source of highly bioavailable essential amino acids as well as minerals and vitamins. However, egg is poor in omega-3 fatty acids. Dietary cholesterol and saturated fat have also been a concern for consumers. This chapter focuses on development of a novel nutraceutical egg product containing minimal levels of cholesterol and reduced saturated fat, but much greater content of omega-3 fatty acids, such as eicosapentaenoic acid, docosahexaenoic acid, and α-linolenic acid, through processing rather than manipulation of the hen’s diet. Further, the physicochemical, sensory, and potential nutritional benefits of the nutraceutical egg product prototype are discussed.