Insight into the spoilage heterogeneity of meat-borne bacteria isolates with high-producing collagenase

Chilled chicken is inevitably contaminated by microorganisms during slaughtering and processing,resulting in spoilage.Cutting parts of chilled chicken,especially wings,feet,and other skin-on products,are abundant in collagen,which may be the primary target for degradation by spoilage microorganisms.In this work,a total of 17 isolates of spoilage bacteria that could secrete both collagenase and lipase were determined by raw-chicken juice agar(RJA)method,and the results showed that 7 strains of Serratia,Aeromonas,and Pseudomonas could significantly decompose the collagen ingredients.The gelatin zymography showed that Serratia liquefaciens(F5)and(G7)had apparent degradation bands around 50 kDa,and Aeromonas veronii(G8)and Aeromonas salmonicida(H8)had a band around.65 and 95 kDa,respectively.The lipase and collagenase activities were detected isolate-by-isolate,with F5 showing the highest collagenase activity.For spoilage ability on meat in situ,F5 performed strongest in spoilage ability,indicated by the total viable counts,total volatile basic nitrogen content,sensory scores,lipase,and collagenase activity.This study provides a theoretical basis for spoilage heterogeneity of strains with high-producing collagenase in meat.

High Pressure Treatment Changes Spoilage Characteristics and Shelf Life of Pacific Oysters(Crassostrea gigas)During Refrigerated Storage

The effects of high pressure(HP) treatment on spoilage characteristic and shelf life extension of Pacific oysters(Crassostrea gigas) during refrigerated storage were studied.Results showed that HP treatment of 275 MPa for 3 min or 300 MPa for 2 min could achieve 100% full release of oyster adductor muscle,pressures higher than 350 MPa caused excessive release as the shells of oysters were broken,thus use of higher pressures should be cautious in oyster processing industry because of its adverse impact on the appearance of shells.HP treatment(300 MPa,2 min) was proper for the shucking of Pacific oyster(Crassostrea gigas) in China.This treatment caused no organoleptic disadvantage.Moreover,HP treatment resulted in obvious differences in biochemical spoilage indicators(p H,TVB-N and TBARS) changes and volatile compounds profile determined by electronic nose during storage.HP treatment(300 MPa,2 min) also led to a reduction of aerobic bacterial count(APC) by 1.27 log cycles.Furthermore,the APC values of oysters treated by HP were always lower than those of the control samples during storage.Based on the organoleptic,biochemical and microbiological indicators,shelf life of 6-8 d for control and 12 d for HP-treated oysters could be expected.HP treatment showed great potential in oyster processing and preservation.

Identification and characterization of Pichia membranifaciens Hmp-1 isolated from spoilage blackberry wine

The pellicle-forming yeast could cause the quality deterioration of wine. In this study, a pellicle-forming strain Hmp-1 was isolated from the spoilage blackberry wine, and identified as Pichia membranifaciens based on the morphology and partial nucleotide sequence of 26S rDNA. The effects of fermentation conditions （ethanol, sulfur dioxide, sugar, and temperature） on the growth of P. membranifaciens strain Hmp-1 and Saccharomyces cerevisiae strain FM^S-115 （a strain used for the blackberry wine fermentation） were investigated, respectively. The results indicated that Hmp-1 had lower resistance to these factors compared to FM-S-115, and the growth of Hmp-1 was completely inhibited by 10% （v/v） or 50 mg L-~ SO2 during the fermentation of blackberry wine. These results suggested that Hmp-1 could effectively be controlled by increasing ethanol or SO2 concentration during the fermentation and storage of blackberry wine. Furthermore, the analysis based on gas chromatography-mass spectrometry （GC-MS） showed that Hmp-1 remarkably decreased kinds of volatile compounds in blackberry wine, especially aldehydes and esters. In addition, some poisonous compounds were detected in the blackberry wine fermented by FM-S-115 and Hmp-l. These results suggested that Hmp-1 was a major cause leading to the quality deterioration of blackberry wine.

Milk Spoilage: Methods and Practices of Detecting Milk Quality

Milk spoilage is an indefinite term and difficult to measure with accuracy. This uncertainty can cause suffering for both milk manufacturers and consumers. Consumers who have been misled by ambiguous expiration dates on milk cartons waste resources by disposing of unspoiled milk or experience discomfort from drinking spoiled milk. Consumers are often unwilling to purchase products close to their inaccurate expiration dates. This consumer behavior has a negative financial impact on milk producers. Inaccurate milk spoilage detection methods also force milk producers to use overly conservative expiration dates in an effort to avoid the legal and economic consequences of consumers experiencing illness from drinking spoiled milk. Over the last decade, new methods have been researched with the purpose of developing more accurate and efficient means of detecting milk spoilage. These methods include indicators based on pH bacteria counts and gas-sensor arrays. This article explores various methods of spoilage detection designed to prevent such consequences. The respective level of effectiveness of each method is discussed, as well as several further approaches to contain freshness regardless of detection.

Characterization of spoilage bacterial communities in chilled duck meat treated by kojic acid

Chilled duck meat is a popularly consumed meat in China but easily perishes at room/low temperature. Kojic acid is usually used as an antimicrobial. This study investigated the sensory scores, total bacteria number, and total volatile base nitrogen (TVB-N) value of chilled duck meat under kojic acid treatment during storage. The results presented that kojic acid suppressed the growth of spoilage bacteria and prolonged the shelf-life of chilled duck meat by at least two days. In further investigation, the bacterial community composition was explored through high-throughput sequencing. Pseudomonas spp. were the predominant spoilage bacteria after 6-day storage and were significantly suppressed by kojic acid. Besides, Brochothrix showed drug resistance and became the dominant bacteria in the kojic acid treated sample after 6-day storage. In conclusion, kojic acid maintained the sensorial, chemical, and microbial quality of duck meat stored at low temperatures. Meanwhile, kojic acid enriched the bacteria composition and showed strong antimicrobial activity against Pseudomonas spp.

Charactering the spoilage mechanism of"three sticks"of Jinhua ham

To investigate the spoilage characteristics of Jinhua ham,sensory scores,volatile compounds,biogenic amine,physicochemical parameters and microbial counts were evaluated between normal and spoiled hams.The results showed that off-odors of spoiled hams were dominated by rancid,sour,sulfide and ammonia odors derived from these compounds including butanoic acid,methanethiol and dimethyl disulfide.Total content of biogenic amine in spoiled hams was significantly higher(more than 10-fold)compared with normal hams,and putrescine,cadaverine and histamine were the key components of biogenic amine of spoiled hams.Lower salt content,and higher moisture,TVB-N and thiobarbituric acid reactive substances(TBARS)values were observed in spoiled hams compared with normal hams.The populations of Enterobacteriaceae and Enterococcus of spoiled hams were obviously higher than that of normal hams.High moisture and low salt content caused the abnormal growth of Enterobacteriaceae and Enterococcus in spoiled hams,which contributed to the spoilage of Jinhua ham.

Effects of <i>Moringa oleifera</i>Leaves and Seeds Extracts against Food Spoilage Fungi

Fungal foodborne diseases pose serious public health problems and cause significant loss of the world’s food stock as a result of toxic contamination. Hence the need to find solutions to foodborne fungal contaminants. This study investigated the antifungal and phytochemical properties of Moringa oleifera leaves and seeds using various extraction solvents (acetone, water, ethanol and methanol). Aspergillus flavus and Aspergillus niger isolated from food samples were used as test organisms. The Agar Well Diffusion method was used to determine the antifungal activities of Moringa oleifera leave and seed extracts, while standard phytochemical tests were used to analyze for the phytochemicals. Moringa oleifera leave and seed extracts showed the presence of glycosides, flavonoids, alkaloids, tannins, saponins, phenols and hydrolysable tannins after the chemical test. At 100 mg/ml for Methanol extract, the leaves gave wider zones of inhibition (18.33 mm against A. flavus and 17.17 mm against A. niger) than the seed extract (16.50 mm against A. flavus and 16.33 mm against A. niger) for all test organism. The activity of the extracts were however lower than Sodium benzoate (33 mm at 100 mg/ml), as standard. The Minimum Inhibition Concentration of the plant extracts was most active at 25 mg/ml. Moringa oleifera leaves and seeds extracts may serve as natural antifungals for controlling growth of food spoilage fungi, and therefore may be used as a bio-preservative agent for prolonging the shelf-life of food products.

Use of Bacteriocin Producing <i>Lactococcus lactis</i>subsp. <i>lactis</i>LABW4 to Prevent <i>Listeria monocytogenes</i>Induced Spoilage of Meat

A bacteriocin producing strain of Lactococcus lactis subsp. lactis LABW4 was isolated from naturally fermented milk product which exhibited strong antibacterial activity against Listeria monocytogenes MTCC657, a food spoilage psychrophilic organism. Both cell free and heat killed supernatants of LABW4 were effective to produce zones of inhibition against L. monocytogenes in vitro. The antibacterial metabolite(s) of LABW4 showed strong cidal effect on the growth of L. monocytogenes. Meat samples, mixed with heat killed supernatant of LABW4 when inoculated with Listeria, remain fresh up to 25 days in refrigerated condition whereas spoilage started immediately after 24 hours of inoculation for control sets. Enhancement of Lactate dehydrogenase of L. monocytogenes upon treatment with LABW4 cell free supernatant suggested its lytic mode of action. Cell lysis or degradations were also supported by scanning electron micrograph of treated cells.

Studies on Fungi Responsible for the Spoilage/Deterioration of Some Edible Fruits and Vegetables

Investigation of fungi responsible for the post harvest deterioration of Lycopersicum esculentus (tomatoes), Elaeis guineensis (palm fruit), Ipomoea batatas (sweet potato), Solanum tuberosum (Irish potato), Musa sapientum (banana), Doucus carota (carrot), Musa paradisiaca (plantain), Carica papaya (pawpaw), Persea americana (Avocado pear), Citrullus lanatus (water-melon) and Capsicum chinense (fresh red pepper) from five different markets and farm lands in Enugu state, Nigeria was carried out. Healthy and diseased samples were collected from the selected markets/ farmlands. Fungal species found associated with the deterioration of the various fruits and vegetables tested included Mucor species (M. indicus, M. amphibiorum, M. racemosus and M. hiemalis), Rhizopus species (Rhizopus stolonifer, R. nigrican and R. oligosporus), Candida albicans, Aspergillus species (Aspergillus fumigatus, A. niger and A. flavus) and Penicillum species (P. oxalicum and P. chrysogenum) and Fusarium species (F. accuminatum, F. oxysporum, F. eqiuseti and F. moniliforme, F. solani, F. dimerum). All isolated fungi were pathogenic to the different fruits and vegetables from the result of pathogencity tests carried out.

Effects of hexanal fumigation on fungal spoilage and grain quality of stored wheat

The prevention of fungal spoilage is an essential consideration in wheat storage.Recent studies have revealed that volatile organic compounds(VOCs),possibly with natural fungicidal properties,could be produced from stored wheat grains.In this study,the antifungal effect of hexanal,a main component of VOCs from stored wheat,against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method.And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content,fatty acid values,germination percentages and vigor of 16%and 18%moisture wheat grains fumigated with 1.66,2.49,and 3.31 mmol/L hexanal vapor.The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal(fatal)concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid,respectively.The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor.During 5-week storage of high-moisture wheat grains fumigated with 1.66,2.49,and 3.31 mmol/L hexanal vapor,the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples,and fatty acid values were slightly higher in 18%moisture wheat than in 16%moisture wheat.The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content.These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.

Species Identification of Mealie Meal Spoilage Organisms and Pathogenic Bacteria from Selected Food Stores in Lusaka District of Zambia

Background: Mealie Meal is one of the by-products of maize from dry milling. It constitutes more significant part of the daily diet of growing population of the Lusaka District of Zambia. However, reported cases of a cholera outbreak in October 2017-May 2018 were attributed to water contamination in the households of Lusaka. Hitherto there is no previous study or documented data for gastroenteritis caused by microbial contamination from food stores. Aim: The main objective of the study was to carry out species identification of Mealie meal spoilage organisms and pathogenic bacteria from selected food stores in Lusaka district from September 2019-March 2020. Crosssectional survey was conducted for food spoilage organisms and pathogenic bacteria of packaged maize meal flour from a selected food store. The number of packaged Mealie meal samples from selected food stores included in the study was 143 samples. Samples were obtained by a simple stratified random selection from food stores in Lusaka District. Thus Mealie Meal samples bought from Street food vendors were 96 (67%), Shops—30 (21%), Malls—17 (11.9%). Subsequently isolation by spread and pour plate methods, and species identification of microbial contamination by Cell Culture processes coupled to microbial morphological and biochemical characterization was performed. Microsoft Office Excel (version 2007) Spreadsheet was employed for the categorical data analysis and summarized graphical presentation of data. Laboratory findings revealed: Spoilage organisms—Aspergillum species, Mucor Species, Candida Species, Clostridium Species and Bacillus Species;Pathogenic Bacteria Species—Clostridium perfringens, Staphylococcus aureus, Clostridium tetani, Bacillus, Escherichia coli, Pseudomonas aeruginosa and Yesinia pestis. It can be established from the laboratory results earlier mentioned that the food poisoning outbreak could evolve from food stores in Lusaka district apart from water contamination.

Portable fluorogenic probe for monitoring of volatile amine vapour and food spoilage

There are urgent needs of volatile amine gas sensors with high-performance in food quality control,disease monitoring and environmental pollution.Thin-film fluorescent probe is suitable for amine vapour sensing due to its high sensitivity,high selectivity,and no polluting analyte.Herein,a novel fluorescent probe based on indacenodithiophene structure withπconjugated system was designed and synthesized.The experimental results show that the films prepared by this material exhibit rapid and distinct fluorescence quenching after being exposed to saturated vapours of primary amine,secondary amine and tertiary amine represented by n-propylamine,diethylamine and trimethylamine,respectively.The quenching of fluorescence is 84%,87%and 96%,respectively,within 10 s.The detection mechanism of probe for primary amine is based on specific chemical reaction,while the detection mechanism for secondary amine and tertiary amine is intramolecular charge transfer.Further experiments show that the detection limit of the fluorescent probe for trimethylamine,an important marker of food spoilage,could reach 4.610 ppt.On-site detection based on spoilage of small yellow croaker suggests the material possesses the potential for food freshness detection.This simple fluorogenic probe is an original approach to simplify real-time visual monitoring of volatile amine vapour.

Spoilage potential of psychrotrophic bacteria isolated from raw milk and the thermo-stability of their enzymes

The storage and transportation of raw milk at low temperatures promote the growth of psychrotrophic bacteria and the production of thermo-stable enzymes, which pose great threats to the quality and shelf-life of dairy products. Though many studies have been carried out on the spoilage potential of psychrotrophic bacteria and the thermo-stabUities of the enzymes they produce, further detailed studies are needed to devise an effective strategy to avoid dairy spoilage. The purpose of this study was to explore the spoilage potential of psychrotrophic bacteria from Chinese raw milk samples at both room temperature （28 ℃） and refrigerated temperature （7 ℃）. Species of Yersinia, Pseudomonas, Serratia, and Chryseobacterium showed high proteolytic activity. The highest proteolytic activity was shown by Yersinia intermedia followed by Pseudomonas fluorescens （d）. Lipolytic activity was high in isolates of Acinetobacter, and the highest in Acinetobacter guillouiae. Certain isolates showed positive ^-galactosidase and phospholipase activity. Strains belonging to the same species sometimes showed markedly different phenotypic characteristics. Proteases and lipases produced by psychrotrophic bacteria retained activity after heat treatment at 70, 80, or 90 ℃, and proteases appeared to be more heat-stable than lipases. For these reasons, thermo-stable spoilage enzymes produced by a high number of psychrotrophic bacterial isolates from raw milk are of major concern to the dairy industry. The results of this study provide valuable data about the spoilage potential of bacterial strains in raw milk and the thermal resistance of the enzymes they produce.

Quick assessment of chicken spoilage based on hyperspectral NIR spectra combined with partial least squares regression

Pseudomonas spp.and Enterobacteriaceae are dominant spoilage bacteria in chicken during cold storage(0°C-4°C).In this study,high resolution spectra in the range of 900-1700 nm were acquired and preprocessed using Savitzky-Golay convolution smoothing(SGCS),standard normal variate(SNV)and multiplicative scatter correction(MSC),respectively,and then mined using partial least squares(PLS)algorithm to relate to the total counts of Pseudomonas spp.and Enterobacteriaceae(PEC)of fresh chicken breasts to predict PEC rapidly.The results showed that with full 900-1700 nm range wavelength,MSC-PLS model built with MSC spectra performed better than PLS models with other spectra(RAW-PLS,SGCS-PLS,SNV-PLS),with correlation coefficient(RP)of 0.954,root mean square error of prediction(RMSEP)of 0.396 log10 CFU/g and residual predictive deviation(RPD)of 3.33 in prediction set.Based on the 12 optimal wavelengths(902.2 nm,905.5 nm,923.6 nm,938.4 nm,946.7 nm,1025.7 nm,1124.4 nm,1211.6 nm,1269.2 nm,1653.7 nm,1691.8 nm and 1693.4 nm)selected from MSC spectra by successive projections algorithm(SPA),SPA-MSC-PLS model had RP of 0.954,RMSEP of 0.397 log10 CFU/g and RPD of 3.32,similar to MSC-PLS model.The overall study indicated that NIR spectra combined with PLS algorithm could be used to detect the PEC of chicken flesh in a rapid and non-destructive way.

A biopolymer-based pH indicator film for visually monitoring beef and fish spoilage

Food safety is a worldwide public concern that has recently gained increased attention due to the emerging outbreaks of foodborne diseases.Therefore,there is a pressing need to make simple,cost-effective,and environmentally friendly methods for detecting food spoilage and to mitigate the impact of possible outbreaks.The aim of this study is to develop a biodegradable indicator film which was made by combining cellulose-nanofiber/chitosan dyed with methyl red synthesis(CCM)as a pH indicator film and followed by a single layer coating of polylactic acid(PLA)on its surface,named PLA/CCM film.The microstructural properties of PLA/CCM films were studied using scanning electron microscopy(SEM)and results showed that PLA effectively adhered to the surface of CCM film.The microbial response to PLA/CCM film was determined via a bacterial plating method.It was found that the contact of film with the microbes caused a substantial color change in the film.The coating of PLA upon the CCM film decreased the percentage of the water vapor transmission rate(WVTR).The color of the film vividly altered from slightly red to yellow in response to a pH change in the range of 4-8.The PLA/CCM film was applied to monitor the spoilage of beef and fish at room temperature(23℃)and revealed the onset of food spoilage by displaying the color change from red to yellow after 1 day.The total viable counts(TVC)of microorganisms and pH of the tested beef sample were determined,and the results revealed that both TVC and pH increased concurrently after beef spoilage.

New strategy to delay food spoilage:Application of new food contact material with antibacterial function

Frequent food poisoning and food-borne diseases outbreaking in recent years have caused people to attach great attention to food safety,especially the food contact materials that are essential in the food industrial chains and daily lives,ensuring their clean sanitation are of great importance in blocking microbial contamination and spread of food-borne pathogens.Stainless steel(SS)is one of the most accepted and widely used food contact material,and the Cu-bearing SS possesses excellent antibacterial performance and maintains the original mechanical properties of SS,maybe making it a better substitute for the conventional SS in the food area.Taking advantages of bactericidal and antifouling properties of Cubearing SS,this study simulated a variety of food contact scenarios,explored a new strategy for food preservation and food safety by using Cu-bearing SS as a food contact material.The results showed that the Cu-bearing SS could not only delay the spoilage of different foods by inhibiting the activity of microorganisms in foods,but also reduce the expressions of spoilage traits of bacteria as well as the formation of biofilms by quenching the quorum-sensing signals,and further creating a good bacteriostatic atmosphere for the contacted food and its surrounding environment.In addition,the remarkable antifouling property of Cu-bearing SS would give the material a self-cleaning feature for food applications,which can avoid secondary contamination of food as a source of contamination.This study well demonstrates that the Cu-bearing SS has broad application potentials and prospects in the food area.

Investigation of spoilage in salmon by electrochemical impedance spectroscopy and time-domain terahertz spectroscopy

In this study,Spoilage of salmon was investigated using electrochemical impedance spectroscopy(EIS)and ter-ahertz time-domain spectroscopy(TDS).Salmon tissues were continuously observed for more than 20 h,from fresh to full spoilage.The complex impedance(Z)and phase shift(θ)of the salmon samples were derived based on the EIS signal.Critical frequency changes,phase shifts,and impedance variations with time at different fre-quencies were extracted from the data and used as indicators of the freshness of salmon.In the THz TDS analysis,time-domain spectra were recorded in transmission and reflection modes.Four stages of fish spoilage were clearly observed in both the EIS and THz TDS spectra.Although EIS is more sensitive under the current experimental conditions,THz TDS in reflection mode provides a non-invasive and non-destructive way to monitor salmon spoilage,which is practically beneficial for the food quality control industry.

Statistical evaluation of beer spoilage bacteria by real-time PCR analyses from 2010 to 2016

A total of 13,802 samples over seven years were investigated using real-time PCR for the presence of beer spoilage bacteria, providing a rare large-scale ove「view of the incidence of individual species. At the same time, the isolation site (early stages of the brewing process=type Ⅰand late stages = type Ⅱ) and the type of contaminated beer and intermediate products (bottomfermented or topfermerited) were evaluated using chi-squared analysis. The most frequently occurring species were Lactobacillus brevis (7 year average 41.9%), Lactobacillus (para-)casei (10.4%).and Lactobacillus backii (9.5%).

Development,Characterization and Application of a Three-Layer Intelligent pH-Sensing Indicator Based on Bromocresol Green(BCG)for Monitoring Fish Freshness

As a novel food quality monitoring technology,intelligent freshness indicator has received wide attention in recent years.However,its poor safety and stability are the main problems hindering its practical application.Hence a new pH-sensing indicator based on bromocresol green(BCG)was developed in this study for nondestructive and real-time monitoring the freshness of marine fishes.The indicator was designed with a three-layer structure,using the polytetrafluoroethylene(PTFE)membrane with high hydrophobicity and air permeability as the inner layer to isolate the moisture in the package,BCG-coated filter paper as the colorchanging layer to indicate the freshness of fish,and a transparent unidirectional permeable(TUP)membrane with moisture resistance as the out layer to isolate the moisture in the environment.This contributed to weaken the influence of humidity and prevent dye migration,so as to improve the accuracy and safety of the indicator.Therefore,a highly sensitive and distinguished color variation response to trimethylamine(TMA)standard solution with different concentrations was observed on the indicator.Additionally,the indicator showed a high color stability at different storage temperatures up to 14 days with total color differences(ΔE)less than 5.0.The indicator presented visible color variations from yellow to green then eventually to blue when applied to monitor the freshness of sea bass and salmon stored at 4℃,implying that fish was spoiled.Meanwhile,indicatorsΔE value was significantly positively correlated with total volatile basic nitrogen(TVB-N)and total viable count(TVC)in sea bass and salmon samples.Thus,the pH-sensing indicator can be applied as a cost-effective and promising intelligent indicator for monitoring fish freshness.

Spectrophotometric Determination of Trimethylamine-nitrogen in Cadaver Tissues for the Estimation of Late Postmortem Interval:A Pilot Study

To study the relationship between the late postmortem interval （PMI） and trimethyl-amine-nitrogen （TMA-N） in postmortem tissues of cadaver, TMA-N in muscles, livers and kidneys of rats was measured at different postmortem intervals （PMI） by using a modified spectrophotometric method. The results indicated that the detection sensitivity of TMA-N was 1 mg/L, and there was a good linear correlation between the value of absorbance （A value） and TMA-N at the concentration of 1-10 mg/L （R2=0.9991）. Although TMA variation in muscles was different from that in inner organs during the time since death, TMA-N changes in cadaver tissues was positively correlated with PMI. During 2 to 7d since death, the best correlation between PMI and TMA-N concentration was found in muscles. With PMI as an independent variable, the cubic polynomial regression equation was y=-0.457x3 ＋6.519x2-24.574x＋27.207 （R2=0.969）. During 3 to 8 days since death, PMI was best correlated with TMA-N concentration in inner organs. With PMI as the independent variable, the cubic polynomial regression equation was y=0.509x3-9.153x2＋55.727x-95.819 （R2=0.953）. It was concluded that TMA-N in tissues could be used as a new estimator for late PMI. The method used in this study offered advantages such as accuracy, sensitivity, little samples required and wide PMI estimation.