effects of hydrocolloid injection on the eating ... - hindawi

Research ArticleEffects of Hydrocolloid Injection on the Eating Quality of PorkAnalyzed Based on Low-Field Nuclear MagneticResonance (LF-NMR)

Shengmei Gai12 Zhonghui Zhang1 Yufeng Zou3 and Dengyong Liu 123

1College of Food Science and Technology Bohai University Jinzhou Liaoning 121013 China2National amp Local Joint Engineering Research Centre of StorageProcessing and Safety Control Technology for Fresh Agricultural and Aquatic Products Jinzhou Liaoning 121013 China3Key Lab of Meat Processing and Quality Control Ministry of EducationJiangsu Collaborative Innovation Center of Meat Processing and Quality Control College of Food Science and TechnologyNanjing Agricultural University Nanjing Jiangsu 210095 China

Correspondence should be addressed to Dengyong Liu jz_dyliu126com

Received 7 October 2018 Accepted 20 February 2019 Published 18 March 2019

Academic Editor Antoni Szumny

Copyright copy 2019 Shengmei Gai et alshyis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

shyis study investigated the eects of hydrocolloid injection on the eating quality of porcine meat based on low-eld nuclearmagnetic resonance (LF-NMR) shye eating quality and water distribution of hydrocolloid-injected pork were compared withcontrol and the principle component analysis (PCA) was applied for the identication of hydrocolloid-injected pork Total colordierence (ΔElowast) cooking loss andmoisture content of hydrocolloid-injected pork were signicantly increased compared with thecontrol (plt 005) LF-NMR indicated that signicant dierences in the relaxation time and peak area proportion of immobilizedwater (T21 P21) and free water (T22 P22) were detected among hydrocolloid-injected samples and the control (plt 005) shye rsttwo principal components (PCs) of PCA accounted for 5407 and 3356 of the observed variation respectively Based on thetwo PCs the hydrocolloid-injected pork could be dierentiated from the control shyerefore LF-NMR combined with PCA oersan eective method for the analysis and detection of hydrocolloid-injected pork

1 Introduction

Ready-to-eat meat is widely consumed in China andWestern countries in recent years Some studies haveshown that adding some edible hydrocolloids in ready-to-eat meat can produce some benecial physiological func-tions such as decreasing blood fat and improving immunity[1] for people Food hydrocolloids have been widely used insausages and minced meat for improving their eatingquality In the process of ready-to-eat meat hydrocolloidssuch as carrageenan and xanthan gum are usually usedto improve the physicochemical properties (WHCand tenderness) and sensory parameters (cook yield)of it Ma et al [2] found that locust bean gum could im-prove WHC cohesiveness and hardness of meat muscleMohan and Singh et al [3] reported that adding 025

kappa-carrageenan during the curing process of beef steakcan increase the cook yield to 781 compared with thecontrol group Jridi et al [4] reported that adding 15gelatin in the raw sausage increased the water-holdingcapacity However above researches only studied the ef-fect of a kind of hydrocolloid on the eating quality of meatproducts and whether the hydrocolloid types have dierenteects on the sensory and physicochemical properties ofmeat products few researches have been carried out in thisaspect especially for ready-to-eat meat

It is suggested that the addition of adequate quantity ofhydrocolloids (such as carrageenan and xanthan gum) hasfavorable eects on ready-to-eat meat quality But manu-facturers may be more concerned about the prots of ready-to-eat meat shyerefore the condition of ready-to-eat meatadulteration or injecting hydrocolloid solutions to ready-to-

HindawiJournal of Food QualityVolume 2019 Article ID 3536824 7 pageshttpsdoiorg10115520193536824

eat meat but not truthfully labeled may exist Meanwhile thecolor and appearance of the ready-to-eat meat were similarto those of the control -erefore it is hard for consumers tomake good judgements by visual inspection or odor in-spection So how to identify whether hydrocolloids has beeninjected to ready-to-eat meat with rapid and nondestructiveway has become a hot research topic Low-field nuclearmagnetic (LF-NMR) as a new detectionmethod can not onlyquickly and noninvasively detect the adulterated foodswhich transverse relaxation time were relatively differentwith quality products but also show the water distributionand the flow of water molecules through hydrogen protonresonance LF-NMR has gained broad interests which isused to assess food quality probe food functionality anddetect food adulteration Li et al [5] demonstrated that low-field nuclear magnetic resonance combined with magneticresonance imaging can rapidly and noninvasively detect andmap adulterated prawns injected with different hydrocol-loids Santos et al [6] reported that whey urea hydrogenperoxide synthetic urine and synthetic milk were added tothe milk samples at concentrations of 5 15 25 35 and 50vv -e result showed that LF-NMR could effectively dis-criminate milk adulteration -erefore LF-NMR has apotential to quickly and nondestructively identifyhydrocolloid-injected meat

-e objective of this research was divided into two partsfirst studying the effects of different hydrocolloids on theeating quality of pork pieces and second exploring whetherLF-NMR combined chemical analysis can quickly andnondestructively distinguish hydrocolloid-added ready-to-eat meat

2 Materials and Methods

21 Preparation of Hydrocolloid Solutions

211 Preparation of Hydrocolloid Solutions at the SameConcentration All hydrocolloids were purchased fromBeijing Solarbio Technology Co Ltd Hydrocolloid solu-tions at the same concentration (03wv) were prepared bydissolving 03 g solid powders into 100mL deionized waterby heating method Subsequently the apparent viscosity(dividing shear stress by the shear rate at a certain velocitygradient) of hydrocolloid solutions were measured imme-diately after cooling to room temperature and the data ofapparent viscosity were obtained by Discovery DHR-1TArheometer (TA instrument USA)

212 Preparation of Hydrocolloid Solutions at the SameApparent Viscosity -e concentrations of different hy-drocolloids for the injection were selected based on theapparent viscosity All hydrocolloid solutions need to bereaching a certain required apparent viscosity so thathydrocolloid-injected meat pieces cannot be distinguishedfrom normal samples by visual inspection and tactile ex-amination So the concentration of each hydrocolloid so-lution was measured by ensuring that the apparent viscosityof each hydrocolloid solution was close to the average valueand fell within the standard deviation of the reference

Xanthan gum (045 wv) carrageenan (020 wv) agar(013 wv) and gelatin (14 wv) solutions were pre-pared separately by weighing 045 g xanthan gum 020 gcarrageenan 013 g agar and 14 g gelatin and then dissolvedin 100mL deionized water by the heating method Statisticalresults showed that the apparent viscosity values of differenthydrocolloid solutions under the abovementioned condi-tions had a similar apparent viscosity (plt 005) (details inTable 1)

213 Measurement of Apparent Viscosity ValuesHydrocolloid solutions were thoroughly stirred beforemeasurement and approximately 3ml of each solution wascoated evenly on the test platform Rheological parameterswere set as follows the temperature of test platform 25degCparallel plate diameter 50mm and the range of shear rate01ndash100 sminus1

22 Preparation of Pork Samples Pork samples (longissimusdorsi muscles) were purchased from a local market Fat andconnective tissues that could be seen by naked eye on thesurface of pork samples were removed then the longissimusmuscles were cut into small pieces (length 60 cmwidth 30 cm and height 40 cm) along the muscle di-rection Subsequently all pieces were divided into controlgroup water-injected group and hydrocolloid-injectedgroup -e control group was prepared without any treat-ment while the water-injected and hydrocolloid-injectedgroups were separately injected with deionized water andhydrocolloid solutions which had the same apparent vis-cosity (the concentrations of xanthan gum carrageenanagar and gelatin were 045 020 013 and 140respectively) Moreover for each sample of water-injectedand hydrocolloid-injected pork three sites were selected forinjecting deionized water or hydrocolloid solutions -edistance between each site was 20 cm and the depth of eachsite was 20 cm -e purpose of that was to acquire theuniform distribution of deionized water or hydrocolloidsolutions in samples Injected samples were allowed to drainand be reinjected to the targeted weight (the percentage was105plusmn 1 of the original weight) [3] Following a 10-min restperiod injected samples were reweighed to ensure deionizedwater or hydrocolloid solutions were assimilated to achieveminimum 105 of the original weight [3] Finally allsamples that contained evenly distributed water or hydro-colloid solutions were acquired

23 Color Analysis -e color of pork samples was measuredby CR-400 chromatic meter (Konica Minolta Japan) beforeand after injection -e total color difference (ΔElowast) wascalculated as follows [7]ΔElowast

(ΔLlowast)2 + (Δalowast)2 + (Δblowast)21113969

In the formula ΔLlowast Llowast1 minusLlowast0 Δalowast alowast1 minus alowast0 andΔblowast blowast1 minus blowast0 ΔLlowastΔalowast andΔblowast revealed the changes of Llowastalowast and blowast respectively Llowast0(lightnessdarkness) alowast0 (rednessgreenness) and blowast0 (yellownessblueness) indicated the colorof porcine meat before injection while Llowast1 alowast1 and blowast1 rep-resented the color after injection -e differences in ΔElowast were

2 Journal of Food Quality

divided into six levels according to the color difference class0ndash05 (trace) 05ndash15 (slight) 15ndash30 (noticeable) 30ndash60(appreciable) 60ndash120 (much) and 120 (very much) -ecolor of each sample was measured 5 times and the averagewas used as the effective value

24 Cooking Loss Measurement -e surface moisture ofpork samples was absorbed by a filter paper then the weightof samples before cooking was recorded asml Subsequentlythe pork samples were placed in plastic bags and immersedin a water bath at 72degC for 60 min to reach an internaltemperature of 70degC After that the samples were removedimmediately and cooled to room temperature for weighingand the weight was recorded as m2 -e cooking loss wascalculated as follows

cooking loss () m1 minusm2( 1113857

m1times 100 (1)

25 Texture Determination A sampler with 2523 cm indiameter was used to acquire samples (diameter 2523 cmheight 15 cm) along the vertical direction of the musclefibers -e direction of myofibrils of samples paralleled tothe probe surface when the texture of samples was measuredby TA-XT2i texture analyzer (StableMicro System UK)-especific parameters were set as follows pretest rate200mms mid-rate 100mms posttest rate 100mmscompression ratio 50 2 times between presses 50 s loadcapacity 50 g trigger type auto probe type P50 and datacollection rate 200 pps

26 Moisture Content Measurement -e moisture contentof samples was measured by oven drying according to themethod of AOAC [8] Samples (approximately 5 g) were putinto weighing bottles which were dried to a constant weightin advance -en the weighing bottles with samples weredried at 102degC in an electric thermostatic drying oven untilthe weight did not change

27 Determination of Transverse Relaxation Time (T2) T2 ofhydrocolloid-injected pork was determined using PQ001

low-field nuclear magnetic resonance analyzer (ShanghaiNiumag Electronic Technology Co Ltd)-e frequency andmagnetic field of spectrometer were 05 T and 22MHz re-spectively -e magnet temperature was set at 32degC Samples(length 3 cm width 1 cm and thickness 1 cm) were ob-tained from each group after water injection or hydrocolloidinjection -e testing samples were placed in nuclearmagnetic tubes with the diameter of 15mm and then wereheated in a 32degC water bath for 10min Subsequently NMRtubes equipped with plugs were put into the magnet cavity ofLF-NMR for acquiring T2 relaxation characteristics whichwere measured by the CarrndashPurcellndashMeiboomndashGill(CPMG) sequence Each sample was repeatedly measured 3times and the average was used as the effective value -erepetition times between two successive scans was 35 s andthe value of τ (time between 90deg and 180deg pulse) was 150 μsData from 3000 echoes were acquired from 16 scanrepetitions

28 Statistical Analysis All measurements were carried outin triplicate and the average was taken as the effective value-e CPMG decay curves were processed by the NMR re-laxation time inversion and fitting system (Niumag Co LtdShanghai China) to obtain relaxation times peak areas andproportions of peak areas Statistical analysis was performedby the ANOVA test using SPSS software (SPSS Statistics190 IBM Chicago Illinois USA) and Duncanrsquos multiplerange test was used to analyze the difference among controland water-injected and hydrocolloid-injected groups(plt 005) Paired sample t-test was applied to analyze porkcolor before and after injection (plt 005) All data wereexpressed as the meansplusmn SD values PCA was carried outusing SPSS 190 Diagrams were plotted using Origin 86software

3 Results and Analysis

31 Apparent Viscosity of Different Hydrocolloids

311 Apparent Viscosity of Different Hydrocolloids at theSame Concentration Table 1 shows the apparent viscosityvalues of different hydrocolloids at the same concentration(03wv) Obvious differences in apparent viscosity valuesamong different hydrocolloids could be observed It hadbeen calculated that the apparent viscosity value of the agarsolution was 26 times higher than that of the gelatin solutionwhich illustrated that the apparent viscosity of differenthydrocolloids at a constant concentration were quite dif-ferent Akhtar et al [9] investigated the influence of theshear-thinning nature of a viscosity-controlling hydrocol-loid system on the sensory perception of taste thickness andcreaminess of model oil-in-water dairy emulsions Malto-dextrin and xanthan were used to adjust the apparent vis-cosity of the systems separately It found that emulsionscontaining the two different hydrocolloids show distinctlydifferent rheological behavior over the shear-rate rangetested-e apparent viscosity of xanthan gum is significantlydifferent from maltodextrin under the same shear rate Forready-to-eat meat which was injected with hydrocolloids

Table 1 Concentration and corresponding apparent viscosity ofeach hydrocolloid solution before injected to meat pieces

Hydrocolloid Concentration ( wv) Apparent viscosity (Pamiddots)Water mdash 023plusmn 008e

Aga 013 103plusmn 015c030 804plusmn 075a

Xan 030 068plusmn 003d045 112plusmn 008c

Car 020 108plusmn 020c030 296plusmn 069b

Gel 030 031plusmn 003e140 109plusmn 019c

Note Values are the average of three independent experiments Differentsuperscripts indicate significant differences (plt 005)

Journal of Food Quality 3

the excessive apparent viscosity of hydrocolloid solutionsmight lead to an unnatural appearance -erefore the ap-parent viscosity of hydrocolloid solutions needed to be takeninto account when hydrocolloids were added to meatproducts A preexperiment of the apparent viscosity ofhydrocolloids showed that the consumers preferred tochoose the meat products that the added hydrocolloids had amoderate apparent viscosity (approximately 10 Pamiddots) -usthe paper investigated the influence of hydrocolloids at thesame apparent viscosity on the eating quality of porcinemeat -e concentrations of different hydrocolloids for theinjection were selected based on the apparent viscosity

312 Concentrations of Different Hydrocolloids at SameApparent Viscosity Values Table 1 shows the apparentviscosity values of different hydrocolloids -e apparentviscosity values of different hydrocolloids ranged from103 Pamiddots to 112 Pamiddots which was significantly higher thanthat of deionized water (plt 005) Moreover no significantdifference was observed among different hydrocolloidsmeaning that these hydrocolloids had the similar fluidity(plt 005) -erefore the values of 045 (wv) 020 (wv)013 (wv) and 140 (wv) were chosen as the concen-tration of xanthan gum carrageenan agar and gelatin so-lutions respectively Sharma et al [10] investigated the effectof selected hydrocolloids on the texture of pureed carrots Itturned out that the apparent viscosity values of three groupswhich separately added xanthan carrageenan and gelatinhad no significant differences under the same rate but theconcentration of each sample was disparate obviously

32 Effects of Different Hydrocolloids on the Eating Qualityof Pork

321 Color -e results of the color analysis of pork samplesare displayed in Table 2 Each row of the table shows thevalues of Llowast alowast and blowast of porcine meat before and after theinjection of hydrocolloids and the value of total color dif-ference (ΔElowast) Statistical results revealed that no significantchanges of Llowast alowast and blowast of all groups were observed(pgt 005) -e value of ΔElowast of the control group was 056and that of water-injected and all hydrocolloid-injectedgroups fluctuated in the range of 161sim299 -e colorchange of control group was described as ldquoslightrdquo and that ofwater-injected and all hydrocolloid-injected groups wereclassified as ldquonoticeablerdquo according to the color differenceclass [7]

Each column in Table 2 reveals the differences in Llowast0 alowast0 blowast0 Llowast1 alowast1 blowast1 and ΔE

lowast among control water-injected andall hydrocolloid-injected groups In comparison with thecontrol group the values of Llowast0 alowast0 blowast0 Llowast1 alowast1 and blowast1 ofwater-injected and all hydrocolloid-injected groups showedno significant differences whereas the ΔElowastvalues of water-injected gelatin-injected and xanthan gum-injected groupsincreased significantly (plt 005) -is may be due to the factthat the values of alowast were related to the concentration ofmyoglobin and the degree of myoglobin denaturationMyoglobin is a kind of water-soluble protein that mainly

distributed in the sarcoplasm of muscular fibers [11] -enumber of myoglobin in the muscles might decrease withthe loss of deionized water or hydrocolloid solutions afterthe injection of water or hydrocolloids which caused ΔElowastdifference of pork samples

322 Texture Properties -e results of the texture prop-erties of pork samples are displayed in Table 3 No significantchanges were observed in gelatin group compared with thecontrol while the other groups changed significantly whichdemonstrated that hydrocolloid types affected the taste ofporcine meat For xanthan gum agar and carrageenangroups the values of hardness gumminess and chewinessincreased significantly (plt 005) After the injection thehardness of xanthan gum group agar group and carra-geenan group increased 1050 1702 and 1123 re-spectively the gumminess increased 2312 1913 and1997 respectively the chewiness increased 29401887 and 2479 respectively Ayadi et al [12] studiedthe influence of carrageenan addition on the properties ofTurkey meat sausages explaining the increase of hardnessand chewiness of carrageenan group might result from theinteraction of carrageenanmdashmuscle proteins

323 Cooking Loss As shown in Figure 1 the cooking lossof the control group was confirmed to be the lowest(2205) Water-injected and all hydrocolloid-injectedgroups revealed a greater cooking loss than the control(plt 005) However there were no significant differencesamong all hydrocolloid-injected groups (pgt 005) meaningthat the cooking loss was not influenced by the types ofhydrocolloids

324 Moisture Content As shown in Figure 2 the moisturecontents of water-injected and all hydrocolloid-injectedpork were significantly higher than those of the controlgroup (plt 005) while no significant differences were ob-served between water-injected and all hydrocolloid-injectedpork (pgt 005) Moreover the statistical results indicatedthat the moisture content was not affected by the types ofhydrocolloids

33 Studyof theWaterDistributionbyLF-NMR As shown inFigure 3 four peaks were observed in samples through themultiexponential fitting of the CPMG decay curves whichwas similar to the spectra of hydrocolloid-injected prawns[5 13] Water in meat or meat products can be classified asfollows strongly bound water (water strongly bound toprotein) weakly bound water (water weakly bound toprotein) immobilized water (water trapped within myofi-brils) and free water (water in the fluid surrounding the cell)in the light of fluidity differences [14 15] -e relaxationtimes of these four peaks (as shown in Figure 3) wereexpressed as T2b (01ndash1ms) Tprime2b (1ndash10ms) T21 (10ndash100ms)and T22 (100ndash1000ms) which were considered as stronglybound water weakly bound water immobilized water andfree water respectively [15] -e fastest fraction the


relaxation times within the range of 0ndash10ms included twopeaks (T2b and Tprime2b) captured about 5 percent of the totalsignal T21 the major fraction the relaxation time within therange of 30ndash60ms captured 80 percent of the total signaland T22 the slowest fraction the relaxation time within therange of 100ndash400ms captured 15 percent of the total signal[16 17]

T2 relaxation times of pork samples are displayed inTable 4 No remarkable differences could be observed for theT2b and Tprime2b values of all hydrocolloid-injected pork samplescompared with the control group which illustrated that thestrongly bound water and the weakly bound water were notaffected by the treatment of hydrocolloid injection More-over both T21 and T22 values of all hydrocolloid-injectedgroups were significantly increased (plt 005) suggesting the

Table 3 Effects of different hydrocolloids in intramuscular injection on texture properties of porcine meat

Hardness Springiness Cohesiveness Gumminess Chewiness ResilienceControl 1385630plusmn 80879a 057plusmn 000 061plusmn 002 838877plusmn 50673a 466910plusmn 48865a 024plusmn 001Xan 1531126plusmn 125857b 058plusmn 002 062plusmn 003 1032784plusmn 108719b 604183plusmn 79763b 025plusmn 001Gel 1308660plusmn 56712a 053plusmn 005 062plusmn 002 808766plusmn 29138a 428844plusmn 40576a 024plusmn 001Aga 1621469plusmn 43465b 055plusmn 003 062plusmn 001 999390plusmn 44176b 555035plusmn 33976b 024plusmn 000Car 1541277plusmn 100157b 058plusmn 003 062plusmn 001 1006435plusmn 59771b 582692plusmn 23280b 024plusmn 000Water 1547539plusmn 47464b 057plusmn 000 063plusmn 001 977807plusmn 47232b 555031plusmn 17539b 024plusmn 001Note Different superscripts in a row indicate significant differences (plt 005)

Control Gel Xan Car Aga Water0

10

20

30

Cook

ing

loss

()

a

b

bb b b

Figure 1 Effects of different hydrocolloids in intramuscular in-jection on the cooking loss of porcine meat

Control Water Gel Xan Car Aga60

65

70

75

80

85

90

Moi

sture

cont

ent (

)

a

bb b b b

Figure 2 Effects of different hydrocolloids in intramuscular in-jection on the moisture content of porcine meat

0

500

1000

1500

2000

2500

3000

3500

4000

4500

001 01 1 10 100 1000 10000

ControlDeionized waterGelatin

AgarXanthan gumCarrageenan

Am

plitu

de

T2 relaxation time (ms)

Figure 3 Distribution of multiexponentially fitted T2 relaxationtime spectra of normal water-injected and hydrocolloid-injectedpork

Table 2 Effects of different hydrocolloids on color assessment of porcine meat

Llowast0 Llowast1 alowast0 alowast1 blowast0 blowast1 ΔElowast

Control 4604plusmn 350 4591plusmn 342 401plusmn 091 425plusmn 089 319plusmn 030 361plusmn 015 056plusmn 012aWater 4605plusmn 283 4819plusmn 169 508plusmn 107 502plusmn 020 388plusmn 129 411plusmn 023 250plusmn 111bGel 4574plusmn 286 4791plusmn 270 400plusmn 088 421plusmn 101 333plusmn 049 364plusmn 079 226plusmn 059bXan 4533plusmn 087 4813plusmn 193 412plusmn 080 407plusmn 084 337plusmn 034 338plusmn 064 299plusmn 113bCar 4730plusmn 372 4785plusmn 166 436plusmn 047 443plusmn 100 385plusmn 091 381plusmn 072 210plusmn 034abAga 4532plusmn 124 4671plusmn 112 463plusmn 017 457plusmn 080 345plusmn 063 313plusmn 073 161plusmn 107ab

Note Different uppercase letters in a row indicate significant differences between before and after injection (plt 005) different lowercase letters in a columnindicate significant differences among different treatments (plt 005)


mobility of immobilized and free water was increased [5]-e comparison of hydrocolloid-injected groups and water-injected group indicated that T21 values of the xanthan gumgroup were obviously lower than that of water-injectedgroup (plt 005) while T22 values of the gelatin groupwere significantly higher than that of the water-injectedgroup (plt 005) Furthermore the comparison amongdifferent hydrocolloids showed that the T22 values of thegelatin group were significantly higher than those of xanthangum carrageenan and agar groups (plt 005) illustratingthat the relaxation time was influenced by differenthydrocolloids

-e peak area proportions of different groups are shownin Table 5 It could be seen that P2b Pprime2b P21 and P22 of allgroups shared 183ndash227 106ndash179 8407ndash9141 and427ndash1232 of total peak areas respectively Compared withthe control group P2b Pprime2b P21 and P22 of hydrocolloid-injected group changed 011ndash044 039ndash063 490ndash658and 544ndash709 respectively It was obvious that P21 and P22changed significantly after hydrocolloid injection -e valuesof P21 of all hydrocolloid-injected groups were significantlylower than that of control group (plt 005) while P22 in-creased significantly (plt 005) meaning that the injection ofhydrocolloid solutions improved the water content of freewater In addition the effect of hydrocolloid types on the peakarea proportion of hydrocolloid-injected pork could beneglected since no significant difference was discovered inP2b Pprime2b P21 and P22

34 Adulteration Analysis of Pork Samples by PCA MethodIn order to identify the hydrocolloid-injected pork from thecontrol LF-NMR data were processed by the PCA method-e purpose of the PCA method was to reduce the di-mensionality of the NMR data set with a large number ofintercorrelated variables and retained as much of theoriginal data as possible at the same time [18] -e scores ofscatter plots of PCA were calculated by LF-NMR data toidentify possible differences among pork samples-e scatter plots of the control water-injected andhydrocolloid-injected pork groups are shown in Figure 4

-e results indicated that two significant components thattotally explained 8763 of the total variance were ob-tained Factor 1 and factor 2 explained 5407 and 3356of the total variance respectively As shown in Figure 4 thedot set of the control group was distributed in Part III andgelatin group was clustered in Part IV while xanthan gumcarrageenan agar and water groups were gathered at theborder of Part I and Part II -is illustrated thathydrocolloid-injected pork could be clearly differentiatedfrom the control based on the difference of LF-NMR data-e overlapping regions in the scatter plot map might beattributable to the similarity in water distribution of thepork samples Overall the results proved that LF-NMRcombined with the PCA method could tell aparthydrocolloid-injected pork from the noninjected

4 Conclusion

In this paper the effects of different hydrocolloid solutionson the eating quality of porcine meat were studied basedon LF-NMR -e results showed that the total color

Table 4 Effects of different hydrocolloids in intramuscular injection on T2 relaxation times of water molecules in porcine meat

Control Xan Car Gel Aga WaterT2b 035plusmn 010 039plusmn 009 045plusmn 004 047plusmn 002 047plusmn 009 045plusmn 009Tprime2b 180plusmn 039a 228plusmn 038ab 238plusmn 062ab 298plusmn 078ab 268plusmn 047ab 315plusmn 085bT21 4329plusmn 000a 4761plusmn 216b 4819plusmn 076bc 4905plusmn 125bc 4857plusmn 110bc 5060plusmn 143cT22 21207plusmn 1351a 26529plusmn 1982b 28652plusmn 907b 34058plusmn 2268c 29088plusmn 1143b 29224plusmn 182b

Note Different superscripts in a row indicate significant differences (plt 005)

Table 5 Effects of different hydrocolloids in intramuscular injection on the proportion of peak area of water molecules in porcine meat

Control Xan Car Gel Aga WaterP2b 227plusmn 022a 207plusmn 020ab 183plusmn 024b 224plusmn 028ab 216plusmn 016ab 202plusmn 018abPprime2b 179plusmn 020a 140plusmn 031b 128plusmn 009b 122plusmn 020b 116plusmn 017b 106plusmn 012bP21 9141plusmn 066a 8635plusmn 221b 8579plusmn 122b 8483plusmn 298b 8651plusmn 220b 8407plusmn 208bP22 427plusmn 084a 971plusmn 252b 1052plusmn 148b 1136plusmn 311b 983plusmn 237b 1232plusmn 236b


ndash2

ndash1

0

1

2

ndash3 ndash2 ndash1 0 1 2 3

Xanthan gumCarrageenanControl

GelatinAgarWater

PC1-5407

PC2-

335

6

III IV

I II

Figure 4 PCA scores for pork samples injected with differenthydrocolloid solutions


difference (ΔElowast) cooking loss and moisture content ofporcine meat were significantly increased after the in-jection of hydrocolloid solutions (plt 005) Textureanalysis indicated that the hardness gumminess andchewiness of porcine meat were affected by the injection ofdifferent hydrocolloids Four distinct peaks correspondingto strongly bound water weakly bound water immobi-lized water and free water in hydrocolloid-injected porkwere observed by LF-NMR -e relaxation time ofimmobilized water increased after the injection of hy-drocolloids while the peak area proportion decreasedsignificantly (plt 005) In addition the relaxation timeand peak area proportion of free water increased signifi-cantly when injecting hydrocolloids into pork (plt 005)PCA results showed that hydrocolloid-injected pork couldbe successfully distinguished from the control In sum-mary LF-NMR combined with PCA can be used as aneffective method for the analysis and detection ofhydrocolloid-injected pork

Data Availability

-e data used to support the findings of this study are in-cluded within the article

Disclosure

Shengmei Gai and Zhonghui Zhang are co-first authors

Conflicts of Interest

-ere are no conflicts of interest regarding the publication ofthis article

Acknowledgments

-is study was supported by the National Natural ScienceFoundation of China (31501410) Chinese National KeyScientific Instruments and Equipment Development Project(2013YQ17046308) and Key RampD Program of LiaoningProvince in China (2017205003)

References

[1] W Zhang S Xiao H Samaraweera E J Lee and D U AhnldquoImproving functional value of meat productsrdquoMeat Sciencevol 86 no 1 pp 15ndash31 2010

[2] F Ma C Chen L Zheng C Zhou K Cai and Z Han ldquoEffectof high pressure processing on the gel properties of salt-soluble meat protein containing CaCl2 and κ-carrageenanrdquoMeat Science vol 95 no 1 pp 22ndash26 2013

[3] A Mohan and R K Singh ldquoFunctional properties of carra-geenan on color stability and sensory characteristics of beefsteaksrdquo Food Bioscience vol 15 pp 72ndash80 2016

[4] M Jridi O Abdelhedi N Souissi M Kammoun M Nasriand M A Ayadi ldquoImprovement of the physicochemicaltextural and sensory properties of meat sausage by ediblecuttlefish gelatin additionrdquo Food Bioscience vol 12 pp 67ndash722015

[5] M Li B Li andW Zhang ldquoRapid and non-invasive detectionand imaging of the hydrocolloid-injected prawns with low-

field NMR and MRIrdquo Food Chemistry vol 242 pp 16ndash212018

[6] P M Santos E R Pereira-Filho and L A Colnago ldquoDe-tection and quantification of milk adulteration using timedomain nuclear magnetic resonance (TD-NMR)rdquo Micro-chemical Journal vol 124 pp 15ndash19 2016

[7] K Jeong O Hyeonbin S Y Shin and Y-S Kim ldquoEffects ofsous-vide method at different temperatures times and vac-uum degrees on the quality structural and microbiologicalproperties of pork hamrdquoMeat Science vol 143 pp 1ndash7 2018

[8] W Horwitz Official Methods of Analysis of the Association ofOfficial Analytical Chemists International Association ofOfficial Analytical Chemists International Gaithersburg MDUSA 17th edition 2000

[9] M Akhtar B S Murray and E Dickinson ldquoPerception ofcreaminess of model oil-in-water dairy emulsions influenceof the shear-thinning nature of a viscosity-controlling hy-drocolloidrdquo Food Hydrocolloids vol 20 no 6 pp 839ndash8472006

[10] M Sharma E Kristo M Corredig and L Duizer ldquoEffect ofhydrocolloid type on texture of pureed carrots rheologicaland sensory measuresrdquo Food Hydrocolloids vol 63pp 478ndash487 2017

[11] G Antonio N Fabio F Daniela et al ldquoMeasurement of meatcolor using a computer vision systemrdquo Meat Science vol 93no 1 pp 111ndash118 2013

[12] M A Ayadi A Kechaou I Makni and H Attia ldquoInfluence ofcarrageenan addition on Turkey meat sausages propertiesrdquoJournal of Food Engineering vol 93 no 3 pp 278ndash283 2009

[13] H Wang R Wang Y Song et al ldquoA fast and non-destructiveLF-NMR and MRI method to discriminate adulteratedshrimprdquo Journal of Food Measurement and Characterizationvol 12 no 2 pp 1340ndash1349 2018

[14] K L Pearce K Rosenvold H J Andersen and D L HopkinsldquoWater distribution and mobility in meat during the con-version of muscle to meat and ageing and the impacts on freshmeat quality attributes-a reviewrdquo Meat Science vol 89 no 2pp 111ndash124 2011

[15] M Tan Z Lin Y Zu B Zhu and S Cheng ldquoEffect of multiplefreeze-thaw cycles on the quality of instant sea cucumberemphatically on water status of by LF-NMR and MRIrdquo FoodResearch International vol 109 pp 65ndash71 2018

[16] H C Bertram A H Karlsson and H J Andersen ldquo-esignificance of cooling rate on water dynamics in porcinemuscle from heterozygote carriers and non-carriers of thehalothane gene-a low-field NMR relaxation studyrdquo MeatScience vol 65 no 4 pp 1281ndash1291 2003

[17] H C Bertram and H J Ersen ldquoApplications of NMR in meatsciencerdquo Annual Reports on Nmr Spectroscopy vol 53 no 4pp 157ndash202 2004

[18] S Geng H Wang X Wang et al ldquoA non-invasive NMR andMRI method to analyze the rehydration of dried sea cu-cumberrdquo Analytical Methods vol 7 no 6 pp 2413ndash24192015


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eat meat but not truthfully labeled may exist Meanwhile thecolor and appearance of the ready-to-eat meat were similarto those of the control -erefore it is hard for consumers tomake good judgements by visual inspection or odor in-spection So how to identify whether hydrocolloids has beeninjected to ready-to-eat meat with rapid and nondestructiveway has become a hot research topic Low-field nuclearmagnetic (LF-NMR) as a new detectionmethod can not onlyquickly and noninvasively detect the adulterated foodswhich transverse relaxation time were relatively differentwith quality products but also show the water distributionand the flow of water molecules through hydrogen protonresonance LF-NMR has gained broad interests which isused to assess food quality probe food functionality anddetect food adulteration Li et al [5] demonstrated that low-field nuclear magnetic resonance combined with magneticresonance imaging can rapidly and noninvasively detect andmap adulterated prawns injected with different hydrocol-loids Santos et al [6] reported that whey urea hydrogenperoxide synthetic urine and synthetic milk were added tothe milk samples at concentrations of 5 15 25 35 and 50vv -e result showed that LF-NMR could effectively dis-criminate milk adulteration -erefore LF-NMR has apotential to quickly and nondestructively identifyhydrocolloid-injected meat

-e objective of this research was divided into two partsfirst studying the effects of different hydrocolloids on theeating quality of pork pieces and second exploring whetherLF-NMR combined chemical analysis can quickly andnondestructively distinguish hydrocolloid-added ready-to-eat meat

2 Materials and Methods

21 Preparation of Hydrocolloid Solutions

211 Preparation of Hydrocolloid Solutions at the SameConcentration All hydrocolloids were purchased fromBeijing Solarbio Technology Co Ltd Hydrocolloid solu-tions at the same concentration (03wv) were prepared bydissolving 03 g solid powders into 100mL deionized waterby heating method Subsequently the apparent viscosity(dividing shear stress by the shear rate at a certain velocitygradient) of hydrocolloid solutions were measured imme-diately after cooling to room temperature and the data ofapparent viscosity were obtained by Discovery DHR-1TArheometer (TA instrument USA)

212 Preparation of Hydrocolloid Solutions at the SameApparent Viscosity -e concentrations of different hy-drocolloids for the injection were selected based on theapparent viscosity All hydrocolloid solutions need to bereaching a certain required apparent viscosity so thathydrocolloid-injected meat pieces cannot be distinguishedfrom normal samples by visual inspection and tactile ex-amination So the concentration of each hydrocolloid so-lution was measured by ensuring that the apparent viscosityof each hydrocolloid solution was close to the average valueand fell within the standard deviation of the reference

Xanthan gum (045 wv) carrageenan (020 wv) agar(013 wv) and gelatin (14 wv) solutions were pre-pared separately by weighing 045 g xanthan gum 020 gcarrageenan 013 g agar and 14 g gelatin and then dissolvedin 100mL deionized water by the heating method Statisticalresults showed that the apparent viscosity values of differenthydrocolloid solutions under the abovementioned condi-tions had a similar apparent viscosity (plt 005) (details inTable 1)

213 Measurement of Apparent Viscosity ValuesHydrocolloid solutions were thoroughly stirred beforemeasurement and approximately 3ml of each solution wascoated evenly on the test platform Rheological parameterswere set as follows the temperature of test platform 25degCparallel plate diameter 50mm and the range of shear rate01ndash100 sminus1

22 Preparation of Pork Samples Pork samples (longissimusdorsi muscles) were purchased from a local market Fat andconnective tissues that could be seen by naked eye on thesurface of pork samples were removed then the longissimusmuscles were cut into small pieces (length 60 cmwidth 30 cm and height 40 cm) along the muscle di-rection Subsequently all pieces were divided into controlgroup water-injected group and hydrocolloid-injectedgroup -e control group was prepared without any treat-ment while the water-injected and hydrocolloid-injectedgroups were separately injected with deionized water andhydrocolloid solutions which had the same apparent vis-cosity (the concentrations of xanthan gum carrageenanagar and gelatin were 045 020 013 and 140respectively) Moreover for each sample of water-injectedand hydrocolloid-injected pork three sites were selected forinjecting deionized water or hydrocolloid solutions -edistance between each site was 20 cm and the depth of eachsite was 20 cm -e purpose of that was to acquire theuniform distribution of deionized water or hydrocolloidsolutions in samples Injected samples were allowed to drainand be reinjected to the targeted weight (the percentage was105plusmn 1 of the original weight) [3] Following a 10-min restperiod injected samples were reweighed to ensure deionizedwater or hydrocolloid solutions were assimilated to achieveminimum 105 of the original weight [3] Finally allsamples that contained evenly distributed water or hydro-colloid solutions were acquired

23 Color Analysis -e color of pork samples was measuredby CR-400 chromatic meter (Konica Minolta Japan) beforeand after injection -e total color difference (ΔElowast) wascalculated as follows [7]ΔElowast

(ΔLlowast)2 + (Δalowast)2 + (Δblowast)21113969

In the formula ΔLlowast Llowast1 minusLlowast0 Δalowast alowast1 minus alowast0 andΔblowast blowast1 minus blowast0 ΔLlowastΔalowast andΔblowast revealed the changes of Llowastalowast and blowast respectively Llowast0(lightnessdarkness) alowast0 (rednessgreenness) and blowast0 (yellownessblueness) indicated the colorof porcine meat before injection while Llowast1 alowast1 and blowast1 rep-resented the color after injection -e differences in ΔElowast were





m1times 100 (1)


































10

20

30

Cook

ing

loss

()

a

b

bb b b



65

70

75

80

85

90

Moi

sture

cont

ent (

)

a

bb b b b


0

500

1000

1500

2000

2500

3000

3500

4000

4500

001 01 1 10 100 1000 10000



Am

plitu

de












4 Conclusion








ndash2

ndash1

0

1

2



GelatinAgarWater

PC1-5407

PC2-

335

6

III IV

I II




Data Availability


Disclosure




Acknowledgments


References























Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018





m1times 100 (1)


































10

20

30

Cook

ing

loss

()

a

b

bb b b



65

70

75

80

85

90

Moi

sture

cont

ent (

)

a

bb b b b


0

500

1000

1500

2000

2500

3000

3500

4000

4500

001 01 1 10 100 1000 10000



Am

plitu

de












4 Conclusion








ndash2

ndash1

0

1

2



GelatinAgarWater

PC1-5407

PC2-

335

6

III IV

I II




Data Availability


Disclosure




Acknowledgments


References























Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018



















10

20

30

Cook

ing

loss

()

a

b

bb b b



65

70

75

80

85

90

Moi

sture

cont

ent (

)

a

bb b b b


0

500

1000

1500

2000

2500

3000

3500

4000

4500

001 01 1 10 100 1000 10000



Am

plitu

de












4 Conclusion








ndash2

ndash1

0

1

2



GelatinAgarWater

PC1-5407

PC2-

335

6

III IV

I II




Data Availability


Disclosure




Acknowledgments


References























Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018






4 Conclusion








ndash2

ndash1

0

1

2



GelatinAgarWater

PC1-5407

PC2-

335

6

III IV

I II




Data Availability


Disclosure




Acknowledgments


References























Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018



Data Availability


Disclosure




Acknowledgments


References























Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018




Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018


effects of hydrocolloid injection on the eating ... - hindawi

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