D. E. BROWN, R. PAUL SINGH, and R. J. COFFELT

A System to Singulateand Align Squid forPackaging and Processing

Introduction

Squid is an important and inex­pensive source of protein in much ofthe world, particularly the Orient.The current annual world catch isestimated at 450 million kg (500,000tons) and a sustainable fishery mayreach 91 billion kg (100 million tons)(Kato and Hardwick, 1975).

The appearance of whole squid inthe local supermarket, where it issold in small amounts, is consideredunpleasant and unappetizing tosome consumers despite the lowretail price for whole squid, $1.52­2.18/kg ($0.69-0.99/pound). Clean­ing squid by hand adds $4.41-6.61/kg ($2.00-3.00/pound) to the pricefor the restaurateur or retail con­sumer.

One species, Loligo opa/escens,commonly referred to as California

ABSTRACT-To reduce packagingtime of whole California market squid,Loligo opalescens, and facilitateautomatic feeding of a newly developedsquid cleaning machine, a system toalign and singulate squid has beendeveloped. Squid are circulated in aholding tank by water jets which alsosingulate and direct the squid throughducts to an alignment slide. The squidslide down the alignment ramp and areoriented mantle first. As the squid slidesdown the ramp, the tentacles drag, caus­ing the body to rotate clockwise orcounterclockwise and orient itself. Dataare presented relating system perform­ance to processing rates for the squidcleaning machine and the packing in­dustry.

June 1981, 43(6)

market squid, abounds off the U.S.west coast. It is currently packed byhand and frozen for foreign anddomestic markets in 0.4, 1.3, 2.2,and 4.5 kg boxes (1, 3, 5, and 10pound boxes). Squid is also handpacked and canned for foreignmarkets. Automatic weighing ma­chines are used in packing squid tobe frozen.~ost hand-packed, boxed, and

frozen squid are left randomlyoriented. The boxes are thenweighed and adjusted to the desiredweight by adding or removing in­dividual squid. Random packing ofsquid which average 13/kg (5.9/pound) in a 0.4 kg (1 pound) boxgenerally takes one worker 5-10seconds' .

Certain processors, in an effort tomake whole, frozen squid more ap­pealing to the consumer, align thetop layer so that the squid areparallel and uniform. A clear plasticwindow in the box cover allows theconsumer to inspect this top layer.This orientation of individual squidis done by hand before or after theboxes are weighed. One processor iscurrently operating a hand packingline, employing 12-15 workers, at56.7 kg/minute (125 pounds/min­ute), using 2.2 kg (5 pound) boxes2

•

'DeLucca, A. 1980. State Fish Co., SanPedro, Calif. Pers. commun.'Nobusada, K. 1980. Sea Products Co., MossLanding, Calif. Pers. commun.

A machine to automatically feedsquid, in a uniformly oriented con­dition, to the workers packaging orcanning whole squid would greatlyreduce packing time.

A machine to skin and eviscerateL. opa/escens has been recentlydeveloped by Singh and Brown(1980). It automatically mounts anindividual squid on a holdingdevice. Using water jets, it skins,eviscerates, and removes the ink sacand backbone in 8 seconds. In aninitial staging area the tentacles aresevered and saved for consumption.The head is also removed. Squid areuniformly oriented and fed into thismachine one by one, mantle first.An orientation device (Brooks andSingh, 1979) was used to feed squidinto this machine. Individual squidwere deposited by hand on thisorientation slide as needed by thecleaning machine. It is estimatedthat a multihead machine (60-70cleaning stations), using the prin­ciples of this prototype, could pro­cess 2,300 kg/hour (2.5 tons/hour).An automatic feeding device, pro­viding oriented, individual squid toeach cleaning station, would greatlyaid in use of this machine by theseafood processing industry.

Materials and Methods

Our singulation technique (Fig. 1,2) was developed to provide aligned,individual squid for processing,either packaging or cleaning. It con­sists of a singulation tank, a circularwater tank, 0.91 m (36 inches) indiameter and 25 cm (12 inches) deepwith a square, 5 x 5 cm (2 x 2 inch),duct (A, Fig. 1), leaving the tank ata tangent. The operating capacity ofthe tank is 210 liters (56 gallons).

The flow of water through duct Ais accelerated by the action of waterjet B (Fig. 1, 3). Water jet B consists

The authors are with the Department of Agri­cultural Engineering, University of Cali­fornia, Davis, CA 95616.

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Figure I.-System to singulate squid.

SINGULATION TANK

SQUID CLEANINGMACHINE

ORPACKING LINE

Conveyor from holding lonks

Water and unused squidreturn to tonk

of a copper tube with an insidediameter of 1.1 cm (0.43 inch). Thewater flow rate through jet B wasmaintained at 0.33 kg/second (5.3gallons/minute) by a centrifugalwater pump. This water jet main­tains the flow of water through ductA at an average velocity of 0.45m/second (1.5 feet/second).

The water in the tank is circulatedby the action of water jets C, D, E,and F (Fig. 1). These jets were madeof 0.25 inch diameter copper tubingand were supplied with a valve tocontrol the flow of water fromthem.

Water jet G mounted in duct H(Fig. 1) was supplied with asolenoid-controlled valve. The flowrate through it when fully developedwas 0.82 kg/second (13.3 gallons/minute). Duct H is 5 cm (2 inches) indiameter. Jet G is aimed at the

Figure 2.-Tank and duct of system to singulate squid.

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Figure 3.-Exit duct from tank and water jet B.

Marine Fisheries Review

entrance to duct I (Fig. 1). Duct Iis also 5 cm in diameter. A flow ofwater through duct I is developed bythe flow of water from jet 0 whenthe solenoid valve is opened. Nor­mally there is little or no flowthrough duct I because the center­line of the exit of duct I is elevated 5cm (2 inches) above the centerline ofduct H.

An alignment slide, J (Fig. I),developed for orientation of squidby Brooks and Singh (1979) into asquid cleaning machine developedby Singh and Brown (1980), islocated at the exit of duct I. Thisslide was made of PVC plastic sheetand was fixed at an angle of 20° withthe horizon. This angle is close tothe minimum angle recommendedby Brooks and Singh (1979). Asmall receiving tank to represent thesquid cleaning machine or packingline was positioned at the base of theslide, K (Fig. 1).

Fresh water was continuallyadded to the system at the rate of0.1 kg/second (1.6 gallons/minute).The overflow was drained off. Thiswas done as a sanitation procedure.

Operation

down duct H (Fig. 1). Squid bodiesremain parallel with duct H as theyflow through it either mantle ortentacles-first. Their average veloc­ity in the duct is 0.45 m/second.

Squid are diverted from duct H toduct I by water jet 0 (Fig. 1). Anelectric eye, M (Fig. I), senses apassing squid and activates asolenoid valve which produces apowerful water jet (0) to divert thesquid into duct I at a right angle tothe flow in duct H.

The squid travels a short distancein duct I and is then deposited onalignment slide J (Fig. I, 4). Thefriction coefficient of the squid ten­tacles, being higher than that of thebody, causes the squid to rotate intothe desired mantle-first alignment asit slides down ramp J (Fig. 1). Singhand Brown (1980) used this align­ment slide to orient squid for theskinning and evisceration machine.Upon reaching location K (Fig. I),the squid are properly aligned andready to enter either a cleaningmachine or a weighing and pack­aging line. The squid that are notremoved from duct H by the water

jet return to the tank and enter thesystem again.

As the numerical density of squidin the tank rises, the likelihood oftwo squid entering the singulationduct A simultaneously, increases.These squids are separated in theduct by the action of water jet B.Water jet B is offset to one side ofthe duct at A and as two squid enterthe duct, they are subjected to avelocity profile difference (Fig. 5) atsection A-A. The squid in the regionof higher velocity accelerates pastthe other squid attempting to enterthe duct at A with it (Fig. 6). Bothsquid then proceed single file.

The placement of water jets C, D,E, and F, and others not shown inFigure 1 insure that all squid arekept circulating in the tank andeventually enter duct H. In closeobservation throughout the devel­opment of this system we observedthat all squid are removed from thesingulation tank. Squid returned tothe tank, not diverted to duct Ibecause jet 0 is closed, are sub­jected to the action of water jets Cthrough F and reenter ducts A and

Squid were batch-loaded into thesingulation tank from a bucket orbin. Continuous loading was alsotried using a metered belt conveyor.The density of squid in fresh tapwater is 1.10 g/cc (Brooks andSingh, 1979) and, as expected, thesquid sink to the bottom of thetank.

Squid are kept circulating in thetank by the action of water jets C,D, E, and F (Fig. 1). The squid, sus­pended in the water, are directed bythe action of jets C, D, E, and Ftoward the exit duct A (Fig. I, 3).The flow of water in this duct is ac­celerated by the action of water jet B(Fig. I, 3). The accelerated columnof water in the duct draws the squid,suspended in the water, which havebeen directed to the duct's entrance,out of the tank. The squid thenleave the tank and flow single file

June 1981, 43(6)

Figure 4.-Squid diverted from ducting and onto alignment slide.

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Figure 5.-Velocity profile in singulation duct at entrance.

to water jet removal station G (Fig.1) were counted. The density of thesquid in the tank was then changedto 30 and 60 squid for to-minuteperiods.

The to-minute test period waschosen because the condition of thesquid deteriorates if exposed tofresh water and repeated action ofthe water jets for a greater period.The mucous-like layer covering thesquid disintegrates. In actual prac­tice this would not be a problem asthe squid would be continuouslyremoved from the system andskinned or packaged. In the abovetests the squid were recycled manytimes.

A second series of tests was per­formed to test the effectiveness ofthe water jet removal device andalignment system. Two modes ofoperation were tested. Continuousoperation would simulate the singu­lation of squid for a packing opera­tion of whole squid. Removal ofsquid from the ducting system ondemand would provide singulatedsquid for a cleaning machine.

In a continuous operation mode,water jet G (Fig. 1) was fixed in theopen position. All squid were to bediverted out of the ducting systemonto the alignment slide. The num­ber of squid in the tank was main­tained at 60 and the duration of thetest was again to minutes. The squidarriving at the bottom of the slide inthe desired condition for packagingin uniform alignment were counted.All squid were returned to the cir­culating tank, thus maintaining 60squid in the tank. The waterdeposited on the slide with the squidwas also recycled by pumping itback into the singulation tank con­tinuously.

In tests simulating the demandsfor aligned squid of the skinningand gutting machine describedearlier, squid were removed fromthe ducting system every 8 seconds.The electric eye controlling water jetG was equipped with a reset circuitwhich prevented its operation until asimulated signal from the squidcleaning machine was received. The

SECTION 0-0

TOP VIEW

Squid (b) occeleroted ond seporotedfrom squid (0) by woter jet

'Mention of trade names, products, or com­mercial firms does not imply endorsement bythe National Marine Fisheries Service,NOAA.

Companyl, Sacramento, Calif., andthawed just prior to use. Theiroverall lengths, from mantle tip totentacle end, ranged from 23 to 33cm (9-13 inches). For the first testthe number of squid in the tank wasmaintained at to for a to-minutetest period. The number of squidremoved and ducted from the tank

SECTION A- A

(Fig. I)

High velocity /flowcreoted by woter "'r'Z"""-;r-=::::::'::::::"'::Ijet B (Fig.l)

Low velocity / flowrote

H within 3 minutes. Similarly theplacement of water jet G insuresthat all squid are diverted from ductH to duct I.

Performance Investigation

The singulation rate for removingsquid from the tank depends onsquid density. Three tests were per­formed to gauge the effect of tankdensity on removal rate. Frozen,whole squid, L. opalescens, werepurchased from Meredith Fish

Figure 6.-Squid separated in singulation duct.

24 Marine Fisheries Review

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20

1.5

O'------J.L.LL"'--­o

NUMBER OF SQUID IN TANI(

Figure 7.-Average singulationrate of squid ducted out of theholding tank.

next squid in the duct then activatedthe electric eye and the water jetdiverted that squid to the alignmentslide. The number of squid in thetank was maintained at 60 and dura­tion of the test was 10 minutes.Squid removed from the ductingsystem and aligned properly wererecorded and the squid were re­turned to the singulation tank.

Results and Discussion

In Figure 7 are shown the resultsof tests performed to determine theaverage removal rate over thelO-minute test period for the duct­ing of squid from the circulationtank. The average removal ratesranged from 0.4 squid/second witha tank density of 10 squid, to 0.8squid/second for 30 squid, and 2.1squid/second for 60 squid. For the60-squid test, the spacing of thesquid in the duct dropped to anaverage of only 25 cm. This is aboutthe minimum spacing required foreffective removal of squid from theduct by water jet G (Fig. 1).

The percentage of squid removedfrom the ducting by water jet Gunder continuous operating condi­tions was at the 92 percent level.With a tank density of 60 squid, 1.9

June 1981,43(6)

100100

80

60

40

20

CONTINUOUSOPERATION

fROMsrNGULoHtON

DUCT

Figure S.-Alignment rate forsquid sliding on inclined ramp.

squid/second on the average weresuccessfully diverted to the align­ment slide under continuous opera­tion. These squid were aligned at a71 percent level (Fig. 8). This islower than the 81 percent levelreported by Singh and Brown(1980), and the 100 percent figurereported by Brooks and Singh(1979). The reasons for this lowalignment rate will be discussedlater.

As noted, 12-15 workers currentlypack squid in 2.2 kg boxes, withthe top layer aligned, at the rate of56.7 kg/minute. Using an averageof 13.0 squid/kg, 12 workers couldpack 740 squid/minute. Eachworker packs on the average 1squid/second. The singulation/alignment technique described inthis report could supply a workerwith 1.9 squid/second if the 100 per­cent alignment rate can be achieved.

The second test for removal ofsquid from the ducting on simulateddemand from the squid cleaningmachine resulted in an 89 percentremoval rate. Every 8 seconds theelectric eye was reset with asimulated signal from the skin­ning/cleaning machine. The firstsquid passing the electric eye ac­tivated the water jet G removal

system (Fig. 1). The squid notremoved by this system remained inthe duct and returned to the circula­tion tank. Those squid that weredeposited on the alignment slidewere aligned at a rate of 76 percent(Fig. 8).

Because the skinning machinedeveloped has an operation time of8 seconds/squid, the singulationmachine could provide squid to alarge number of skinning machines.Multiple solenoid-controlled waterjets diverting squid would be re­quired. With a maximum removalrate from the singulation tank of 2.1squid/second, this singulationdevice could automatically feed15-17 squid skinning machines.

These squid removed from theducting system and deposited on thealignment slide were aligned at alower than expected rate. Figure 8compares these results with previousresearch. Singh and Brown (1980)reported an alignment rate of 81percent for squid deposited on thealignment slide of the squid cleaningmachine described. In a publicdemonstration of the squid cleaningmachine on 19 April 1980, a near100 percent alignment rate wasobserved. The sample size was 150squid. Brooks and Singh (1979)found a 100 percent alignment ratefor squid dropped on an alignmentramp. Operated continuously thealignment slide in this report alignedsquid at a 71 percent rate. On simu­lated demand, a 76 percent rate wasachieved (Fig. 8). The two mostlikely reasons for the difference inperformance are: 1) The quantityof water dropped on the slide withthe squid; and 2) the material thatthe slide is made of. Brooks andSingh (1979) observed squid orienta­tion on a galvanized sheet-metalramp with a constant fine spray ofwater to facilitate the sliding mo­tion. The squid cleaning machinedeveloped by Singh and Brown(1980) used a Plexiglas slide andfine water spray to orient squid.Large amounts of water are de­posited along with the squid by thesystem described in this report. PVC

25

plastic was used in the constructionof the slide.

A mechanical device to separatethe squid from excess water andthen drop the squid on the slide isneeded to improve the alignmentrate. An investigation of the slidematerial and its effect on the fric··tion coefficient of squid tentaclesand body would be necessary toselect the optimum material for thiscomponent of the system. Stainless

26

steel would be preferred by the processing industry.

Acknowledgment

This research was supported bySea Grant, Project No. R/F-33, Na­tional Oceanic and AtmosphericAdministration, U.S. Departmentof Commerce. The authors alsowish to thank James Bumgarner,Agricultural Engineering Depart­ment, University of California,

Davis, for the artwork included inthis report.

Literature Cited

Brooks, L. A., and R. P. Singh. 1979. Prop­erties of squid useful in designing of clean­ing and handling systems. Transactions ofthe ASAE. 22(3):658-663.

Kato, S., and J. E. Hardwick. 1975. TheCalifornia squid fishery. FAO Fish. Rep.170, Suppl. 1:108-128.

Singh, R. P., and D. E. Brown. 1980.Development of a squid skinning andeviscerating system. Mar. Fish. Rev.42(7-8):77-84.

Marine Fisheries Review