That one final push
Extracting as much sucrose as possible from one of the last batches of ‘pure cane sugar from Hawaii’
EDITOR’S NOTE: “The Last Harvest” is a series chronicling the various aspects of Hawaiian Commercial & Sugar Co.’s final harvest as it shuts down at the end of the year after a 145-year run. The shutdown of HC&S represents the end of sugar in Hawaii. The installments will run periodically throughout the year.
In a great big basin of thick, goopy molasses, a set of wheels slowly rotates, sinking into the pool of shiny liquid and emerging with a viscous, dark brown coating that slides off and flaps in the wind before dripping back into the basin.
In the Puunene Mill at Hawaiian Commercial & Sugar Co., this is the last recovery stage, that one final push to get as much sugar as possible from the cooled molasses before it’s sent out of the factory as a final product.
HC&S can get about 84 to 86 percent of the sucrose out of the original cane, which is “very good” within the industry, said Anna Skrobecki, senior vice president of factory and power plant operations. The rest gets lost in the mud, molasses and bagasse, which is the leftover cane fiber.
Since the Puunene Mill processed its first harvest in 1902, some of the equipment is different and most everything has become automated now.
“But the fundamental process hasn’t changed,” Skrobecki said.
Sugar making, at once an art and a science, is on display for the last time in Hawaii as HC&S prepares to close down at the end of the year. Many residents and visitors to Maui are familiar with the beginning and end of the process. They’ve driven past the fields of leafy green cane. They’ve seen the glow of fires during harvesting and the burned brown piles of cane collected afterward. But then the stalks disappear into the factory to be transformed into glistening crystals of sugar.
Even some HC&S employees “don’t know how we make the sugar,” said Rogelio Villanueva, a 65-year-old veteran sugar boiler with the company.
Villanueva’s job comes at a crucial point, when the crystals of sugar are starting to grow. But long before the sweet substance arrives at the boiling house, it must go through a series of smashing and squeezing in the mill’s monstrous machinery.
From Stalk to Juice
On a sunny Friday in November, cool breezes are sweeping fresh air and sweet relief through the steamy mill. In less than two months, HC&S’ very last harvesting season will come to an end, 145 years after parent company Alexander & Baldwin planted its first sugar cane crop.
But today, it’s just business as usual.
Outside the factory, the heaping piles of sugar cane sit on the unloading table awaiting transport inside. The long, skinny stalks are muddied and recently burned. Towering cranes overhead grasp at the piles to help untangle them.
Aside from the expected mud and rocks, cane fields get mucked up with all kinds of garbage, including car parts and home appliances.
“We’ve got the dump right in the middle of the plantation,” Skrobecki said of the Central Maui Landfill. “But some people don’t even bother to go as far as the dump.”
So first, the cane has to be cleaned. Slowly, the stalks ascend a conveyor belt to a large bin of water known as the sink float. Here, the heavier mud and debris fall to the bottom, while the lighter cane is picked up and transported up another conveyor belt under a spray of recycled mud water.
Skrobecki said the mill tries to use fresh water only when necessary. That comes in one of the last cleaning steps. The cane will travel up a ramp that bounces the cane under a shower of freshwater, revealing the stalks’ yellowed skin and notches, resembling bamboo. Unlike the hollow bamboo, however, sugar cane is packed inside with ripened juices.
Robert Luuwai, vice president of factory operations, said getting sugar from the cane involves “a whole bunch of separations.” The machines separate the juice from the fiber, then the dirt and water from the juice (to create a syrup), and finally the sucrose from the syrup (to create sugar crystals).
Once the stalks are rinsed off, this process of separations can start. First, the cane undergoes “the knife,” which is a set of blunt-edged blades that smack the cane and split the stalks. Then it’s pushed into a shredder that ruptures the cells so juice can be extracted.
The crushed cane, which looks like a mound of damp sawdust at this point, must pass through high-pressure rollers on four identical mills. Skrobecki described it as similar to squeezing liquid out of a wet, soapy sponge.
“Each of the mills is only capable of squeezing so much moisture out of the bagasse,” Skrobecki said. “You’ll never get it totally dry.”
To get all the soap out of a sponge, you have to rewet it and squeeze it over and over, Skrobecki pointed out. The same is done with the cane. The diluted juice is used to rehydrate the bagasse, which is squeezed in each mill to get the maximum amount of juice out. The more mills the cane goes through, the more sucrose the factory can get out of it.
Once the juice is squeezed out, it’s weighed, treated with lime and sent off to be boiled.
Turning Up the Heat
Villanueva comes in at 6 a.m. each day to check on the boiling house equipment and make adjustments as needed. Seated in front of half a dozen flat-screen PCs, he scans the complex array of shapes and numbers, his experienced eyes ready to tell him if something’s amiss.
“Our mind has to be in so many places at one time,” sugar boiler mechanic Wesley Saito said. “People think our job is only to sit here and check the computers. This thing only going tell you so much.”
At times, Villanueva and Saito have to check the actual equipment to make sure the process is running smoothly.
The boiling house is home to a series of towering metal cylinders called evaporators, which take in the juice after it’s been clarified of mud. Through the small portholes fixed on each evaporator, the amber-colored juice can be seen sloshing and hopping in a violent boil. The temperature will drop with each evaporator, but the syrup level will climb, going from about 220 degrees Fahrenheit and a 12 percent syrup level to 135 degrees and 65 percent syrup. Then it’s time to get the sugar crystals out of the syrup.
In gigantic tanks known as batch pans, the syrup is boiled and a slurry of white granulated sugar is introduced into the mixture, Luuwai explained. Putting these tiny crystals, or “seeds,” into the mix helps the crystals grow uniformly. Workers scrutinize samples under the microscope periodically, and with the computers can add water or syrup to the pan depending on the growth rates.
“These guys . . . they have to watch what they’re doing, and with their experience, they can tell how it affects things,” Luuwai said. “They’ll watch the grain size, make sure it’s consistent, and then they’ll decide when it’s the right size, they’ll send it to a centrifugal.”
At that point, the product is known as massecuite, a mix of sugar crystals and molasses that must be separated in the centrifuges. Skrobecki compares the squat, cylindrical tanks to salad spinners. They whirl the massecuite at a high speed and push out the molasses, which is taken to another part of the factory to be reboiled and centrifuged again to try to extract more sugar. The finished crystals drop out of the centrifuge onto a fast-moving conveyor belt that will take the completed product out of the factory.
Skrobecki sweeps her hand through the conveyor belt and picks up a small clump of raw sugar, showing off the sparkling crystals. The raw sugar will be stored in massive piles in a warehouse in Kahului and then shipped by barge to a refinery in Crockett, Calif.
In one year, HC&S produces 180,000 to 200,000 tons of sugar, 50,000 to 55,000 tons of molasses and about 500,000 tons of bagasse, according to Skrobecki. Sugar cane’s two byproducts, molasses and bagasse, are both useful products on their own.
Bagasse is the primary fuel source for the factory’s operations. It’s everywhere, swirling around the factory like a delicate snowfall, leaving sawdust-like flecks on shirts and jeans and piling up on the mill’s machinery. Once the cane has been squeezed through the four mills, the leftover bagasse is ferried on a conveyor belt to a spacious warehouse known as the bagasse house. Here, it’s raked out evenly across the floor and prepared for transport to the power plant.
Bagasse is more efficient than oil but less efficient than coal, Skrobecki explained. During the offseason, or when maintenance is taking place in the bagasse house, the factory uses coal. Oil only comes into play as an emergency fuel or to help gradually warm up boilers that are starting out cold.
Meanwhile, the final molasses, which will be processed for every bit of sugar it can offer, gets shipped to the West Coast and to Asia to be used as cattle feed, Luuwai said. When the weather is dry, local ranchers also use the molasses to mix with low-quality feed, packing it with minerals and making it more palatable for the cattle.
Even the mud that’s washed out of the cane stalks and juice can be collected to use again on land.
For Villanueva, the best byproduct of the sugar-making process is the group of co-workers he’s come to know as family. His favorite part of the job is to “make joke to the boss,” he said, grinning at Luuwai.
When the machines finally go silent and HC&S closes up shop, “we going lose all the happiness here,” Villanueva said.
* Colleen Uechi can be reached at email@example.com.