Li Zhen Ma

Bio: Li Zhen Ma is an academic researcher from Tianjin Agricultural University. The author has contributed to research in topics: Hydrolysate & Catfish. The author has an hindex of 3, co-authored 10 publications receiving 47 citations.

Low Field-NMR in Measuring Water Mobility and Distribution in Beef Granules during Drying Process

Abstract: Low field-nuclear magnetic resonance (LF-NMR) was employed in this study to evaluate water mobility and distribution in beef granules during drying process due to its fast and nondestructive detection. Beef granules were dried in a blast drying oven at different temperatures (40, 50 and 60 °C) to a final moisture content around 21% after cooking. Results showed that it took about 150, 90 and 60 min for the samples dried at 40, 50 and 60 °C to get to the drying destination, respectively. The immobilized water was transformed into bound water with lower association degree and free water during drying at different conditions. Drying also resulted in a proportion increase of bound water; what’s more, the proportion of bound water is the largest when drying at 50 °C compared to 40 and 60 °C. After the drying destination was reached, the transverse relaxation time for bound water and immobilized water appeared significant change. It revealed that LF-NMR was an effective tool to assess water mobility and distribution during food drying process.

Chemical Composition Analysis of Three Commercially Important Fish Species (Sardine, Anchovy and Mackerel)

Abstract: Crude protein, total lipids, moisture, total ashes and selected mineral (Ca, Mg, Fe, Zn, Cu, Mn) content, fatty acid and amino acid composition were determined in the muscle tissue of three widely consumed fish species (sardine, anchovy and mackerel) obtained from Quanzhou of China. All fish species were high in protein (21.46%~22.75%), with total lipid and moisture content varied from 2.24% to 8.23% and from 69.7% to 74.9%, respectively, depending on the species. Total ash content range from 1.25%~1.63% but macrominerals content varied considerably with Mg content ranged from 470.24mg/100g to 687.45mg/100g and Ca levels ranged from 16.40mg/100g~109.22 mg/100g depending on the species. The most abundant microminerals were Fe and Zn followed by Cu and Mn. In all the three species, palmitic acid (28.44%~30.62%) was the predominant saturated fatty acid. Oleic acid (11.23%~22.15%) was the most abundant monounsaturated fatty acid. DHA was the main polyunsaturated fatty acids, followed by EPA. Sardine had the highest DHA (12.74%). Amino acid compositions were similar for the three species which were high in glutamate, lysine, leucine and aspartate and low in cysteine. Almost all amino acids content of anchovy were higher than other two species.

Effect of Catfish Bone Hydrolysate on the Quality of Catfish Sausage During Ambient Temperature (37 °C) Storage

Abstract: The purpose of this study was to evaluate the effect of catfish bone hydrolysate (CBH), at levels of 0.5, 1.0, 1.5 and 2.0%, on the quality of catfish sausage stored at ambient temperature (37 °C). The results showed that sausages with addition of CBH had lower pH, lower TVB-N and lower total plate count during storage. The lightness (L*), redness (a*) and yellow (b* ) values of sausages with CBH were lower than control before storage. During storage, the L* values of the sausages with CBH decreased significantly. The a* values and the b* values changed slowly. Samples with 1.5% CBH had higher overall acceptance during storage.

Effect of Oxidized Myofibrils Protein Subjected to Mutiple Freeze-Thaw Cycles on N-Nitrosamine Formation in In Vitro Model System

Abstract: N-nitrosamine is a kind of carcinogenic substance, which is possibly formed in the reaction of nitrites with amino acids or secondary amines. Two in vitro model systems were designed to evaluate the influence of oxidized myofibrils protein subjected to repeated freeze-thaw cycles (0, 1, 2, 3, 4, 7, 10 times) on N-nitrosamine formation. Model system I contains diethylamine and sodium nitrite, while model system II contains only sodium nitrite as reaction solution. Oxidized myofibrils protein were added to both systems. The results revealed that as the number of freeze-thaw cycles increased, cross-linking of myosin heavy chains and the content of protein carbonyl increased, but the content of protein sulfydryl decreased, which indicates oxidization of protein occurred. The concentration of N-nitrosodiethylamine increased as the number of freeze-thaw cycles increased, especially after four cycles. Oxidized myofibrils protein promoted the formation of N-nitrosodiethylamine. The more the times of freeze-thaw cycles were subjected, the more oxidization of myofibrils protein occurred and the higher yield of the N-nitrosodiethylamine.

Determining the Impact of Celery Powder and Starter Culture on Quality of Indirectly Cured, Emulsified Cooked Sausages

Abstract: The objective of this study was to determine the effect fresh celery powder and starter culture (FCP+SC), blanching celery powder and starter culture (BCP+SC) had on the quality characteristics of indirectly cured sausages, Two treatments (TRT) (TRT 1: FCP+SC, 0.3%FCP+0.033%WBL-45; TRT 2: BCP+SC, 0.3%BCP+0.033%WBL-45 ), Negative Control (NC) (no-nitrite-added control), Positive Control (PC) (0.1%sodium nitrite-added control) were investigated. Residual nitrite levels throughout storage is always higher in PC than FCP+SC and BCP+SC(P < 0.05), but in TBARS, PC is better than FCP+SC and BCP+SC(P < 0.05). Few differences existed between TRTs and PC for a* and gel strength. The processing methods investigated to manufacture “naturally cured” in this study were applied for products instead of sodium nitrite.

Methods in Enzymology.

Abstract: I read this book the same weekend that the Packers took on the Rams, and the experience of the latter event, obviously, colored my judgment. Although I abhor anything that smacks of being a handbook (like, \"How to Earn a Merit Badge in Neurosurgery\") because too many volumes in biomedical science already evince a boyscout-like approach, I must confess that parts of this volume are fast, scholarly, and significant, with certain reservations. I like parts of this well-illustrated book because Dr. Sj6strand, without so stating, develops certain subjects on technique in relation to the acquisition of judgment and sophistication. And this is important! So, given that the author (like all of us) is somewhat deficient in some areas, and biased in others, the book is still valuable if the uninitiated reader swallows it in a general fashion, realizing full well that what will be required from the reader is a modulation to fit his vision, propreception, adaptation and response, and the kind of problem he is undertaking. A major deficiency of this book is revealed by comparison of its use of physics and of chemistry to provide understanding and background for the application of high resolution electron microscopy to problems in biology. Since the volume is keyed to high resolution electron microscopy, which is a sophisticated form of structural analysis, but really morphology in a modern guise, the physical and mechanical background of The instrument and its ancillary tools are simply and well presented. The potential use of chemical or cytochemical information as it relates to biological fine structure , however, is quite deficient. I wonder when even sophisticated morphol-ogists will consider fixation a reaction and not a technique; only then will the fundamentals become self-evident and predictable and this sine qua flon will become less mystical. Staining reactions (the most inadequate chapter) ought to be something more than a technique to selectively enhance contrast of morphological elements; it ought to give the structural addresses of some of the chemical residents of cell components. Is it pertinent that auto-radiography gets singled out for more complete coverage than other significant aspects of cytochemistry by a high resolution microscopist, when it has a built-in minimal error of 1,000 A in standard practice? I don't mean to blind-side (in strict football terminology) Dr. Sj6strand's efforts for what is \"routinely used in our laboratory\"; what is done is usually well done. It's just that …

Volatile N-nitrosamines in meat products: Potential precursors, influence of processing, and mitigation strategies.

Abstract: Meat products can be contaminated with carcinogenic N-nitrosamines, which is ascribed to the reaction between a nitrosating agent, originating from nitrite or smoke, and a secondary amine, derived from protein and lipid degradation. Although in model systems it is demonstrated that many amine containing compounds can be converted to N-nitrosamines, the yield is dependent of reaction conditions (e.g., low pH and high temperature). In this article, the influence of the composition of the meat products (e.g., pH, aw, spices) and processing (e.g., ageing, ripening, fermentation, smoking, heat treatment and storage) on the presence and availability of the amine precursors and the N-nitrosamine formation mechanism is discussed. In addition, this article explores the current N-nitrosamine mitigation strategies in order to obtain healthier and more natural meat products.

Peptides and protein hydrolysates as food preservatives and bioactive components of edible films and coatings - A review

Abstract: Background The consumer demand for food that is minimally processed and that does not include artificial additives makes it necessary to look for new natural sources of preservatives and active packaging that extends the shelf-life of food products. Protein hydrolysates and biologically active peptides isolated from food proteins, due to their antioxidant and antimicrobial activity, can be used as natural food preservatives. In addition, it is possible to include them in packaging materials as active ingredients. Scope and approach In this paper, the possibilities of using protein hydrolysates and biopeptides are characterized as ingredients extending the shelf-life of food by adding them directly to food products, or as biodegradable ingredients of edible active packaging. The full implementation of bioactive peptides and protein hydrolysate is postponed by some challenges such as their low chemical stability, bitter taste and short-term effectiveness. Encapsulation, which is also discussed in this work, could help overcome these limitations. Key findings and conclusions It has been found that protein hydrolysates and their biopeptides directly added to food products, already in small doses, mostly inhibit fat oxidation and inhibit the growth of microorganisms. Edible active packaging materials with bioactive peptides and protein hydrolysates have shown effectiveness in inhibiting pathogenic microorganisms and lipid oxidation, improving food safety. In several studies, significant changes have been indicated in the mechanical properties and surface morphology of films with the addition of protein hydrolysate and peptides. Nonetheless, the direction of these changes depends on the type of incorporated protein hydrolysates. Protein hydrolysates and biologically active peptides are a promising alternative to synthetic preservatives and active ingredients of biopolymer films. However, further research should be carried out, focusing on the search for new sources of these compounds and assessing their safety.