Research method

Observation of Phase Behavior of Fat Crystals
during Rapid Cooling

X-ray diffraction/scattering

Elucidation of mechanism behind the formation of molecular compound

Role of SPring-8

Achievements

In situ observation of phase behavior and polymorphic changes of fat crystals
during rapid cooling in margarine manufacturing process
Determination of cooling rate and post-cooling heating temperature required forthe formation of molecular compound (MC)*The formation of MC will be controlled by adjusting the manufacturingconditions
R&D Institution: Miyoshi Oil & Fat Co., Ltd.

*MC: Molecular compound crystal formed by binding different molecules at a certain ratio. Its properties are different from those of their component
molecules. POP and OPO, the main components of palm oil and pork lard, respectively, form MC at a ratio of 1:1.

BackgroundResults

Recently, it has been reported that theconsumption of foods with high contents ofsaturated and trans fatty acids increases therisk of diseases such as myocardial infarction
and diabetes. However, oil and fat products
such as margarine are required to have somedegree of firmness for consistency andplasticity. If the contents of the saturated andtrans fatty acids are decreased, the propertiesof oil and fat products will greatly change.
We focused on the MC as a means ofsolving the above problem. The MC crystals
are rich in oleic acids, giving them a healthy
image, and have moderate hardness because
they are solid at room temperature. Thus, weexpect to use them as alternatives tosaturated and trans fatty acids. However, theircrystal phase behavior during rapid coolingat a rate of ≥ 100 oC/min in the manufacturing
process has not yet been clarified.

In a preliminary experiment, we prepared a sampleof MC crystals by mixing 1,3-dioleoyl-2-palmitoyl
glycerol (OPO) and 1,3-dipalmitoyl-2-oleoyl-sn- glycerol(POP) at a ratio of 1:1 and measured a thermogram bydifferential scanning calorimetry (DSC) while changing
the cooling rate. The thermogram clearly shows that theformation of MC greatly depended on the cooling rateand drastically changed at 40 oC/min and above.
Next, time-resolved X-ray diffraction measurement
was carried out using high-brilliance synchrotronradiation at SPring-8, which enables the continuous
observation of the behavior of fat crystals as they quickly
change over a few seconds, as follows. The sample wascooled slowly (5 oC/min) and rapidly (40 oC/min). Next, it
was heated (10 oC/min). The analysis of the phasebehavior and polymorphic changes of the sample
revealed the cooling rate required to form MC and theoptimum temperature for its efficient formation.
Therefore, the MC formation can be controlled byadjusting the cooling rate and product temperature.

X-ray diffraction measurement under different cooling and heating conditions

A sample was prepared by mixing POP and OPO, the main component of palm oil and lard, respectively, at a ratio of 1:1. Time-resolved X-ray
diffraction measurement was carried out during slow and rapid cooling and also during heating in the temperature range from −50 to −100 oC.
We analyzed the phase behavior and polymorphic changes of MC crystals during cooling and heating. The results suggest the possibility ofcontrolling MC formation by adjusting the cooling rate.

Oil phase Aqueous phase

0-50-100POP-2012. Pasteurization

2350
4

1. Emulsification

678

9 10 11 12 13 14 15 16 17 18Productoutflow

Outflow
Shaft
product

Rotation

Inner tube

refrigerant

Margarine is manufactured by emulsifying the oil and aqueousphases, pasteurizing, rapidly cooling, kneading, and packing. In
the process of rapid cooling and kneading, the product is cooled
by a scraped-surface heat exchanger. The cooling rate is estimatedto be at least 100 oC/min.

1.6

0.37

0-5-10-50

0.41 0.38

5.3 2.6050
12345678

9 10 11 12 13 14 15 16 17 18(2) Cooling rate, 40 oC/min

00.38
0.37
0.52 0.45 0.44 0.40 0.36

Heating-105037.5

MC + POP + OPO
123456789 10 11 12 13 14 15 16 17 18-50(3) Heating at 10 oC/min after slow cooling at 5 oC/min

The weak diffraction peaks of POP and OPO crystals disappeared uponheating. This indicates that the POP and OPO transformed into MC.

4.2(nm)40

POP + OPO

3.2

MC

1.4(a) 50(nm)510-20POP
disappearance

OPO
disappearance

20

No diffraction peaks of MC crystals were observed, indicating that no MC wasformed during rapid cooling.

302010MC formation

1.400.38
0.44 0.40 0.37

Heating-10

POP + OPO

-20-300.45123456780.410.37

9 10 11 12 13 14 15 16 17 185038-50

Temperature / oC

Inflow(a) 10Temperature / oC

Refrigerant
inflow

Time-resolved X-ray diffraction
measurement was carried outusing a small-angle scattering
device at BL19B2. The sample
was cooled slowly (5 oC/min)and rapidly (40 oC/min) from100 to −50 oC using liquidnitrogen. Next, it was heated ata rate of 10 oC/min from −50 to100 oC.

Strong diffraction peaks of MC crystals were observed, confirming that theMC was formed during slow cooling. Moreover, weak diffraction peaks ofPOP and OPO crystals were also observed, indicating that some of the POPand OPO were independently formed.

Intensity / counts

GapShaft

125(1) Cooling rate, 5 oC/min

Refrigerant
outflow
Scraperblades

Productinflow

0.52

0.38

Temperature / oC

Emulsification
tankOPO

100.45Temperature / oC

5. Packing

1.4(nm)30MC

204.2(a)(nm)

4.230

Intensity / counts

4. Kneading(a)Intensity / counts

3. Rapid coolingTime-resolved X-ray diffraction measurement at
SPring-8

Intensity / counts

Manufacturing process of margarine(4) Heating at 10 oC/min after rapid cooling at 40 oC/min

As the diffraction peaks of POP and OPO crystals weakened, diffraction peaksof MC crystals started to appear and increased in the intensity while heating.
This suggests that the POP and OPO that had formed independently
transformed into MC upon heating.

13