Chapter 190: The Versatility of Sweet Potatoes

Gears may seem simple, but they are technically complex and a hallmark of an industrial society. Ancient societies also had gears; both China and Europe have records of gear systems. However, the modern gear originated in 1765 with the mathematician Euler’s proposal of the gear involute. With the involute gear and the fundamental law of gear meshing, high-speed gear transmission became possible. Without the involute gear, there would be no high-speed transmission, no gearbox, and without a gearbox, the transmigrator industry could not efficiently use any powerful form of energy.

For the members of the Engineering and Energy Committee, designing most industrial gears was not a problem—they had countless technical materials available, and the manufacturing difficulty was not great. They had a gear hobbing machine, and even if they didn’t, several machining enthusiasts said they could replicate one through machining and casting. The difficulty lay in finding suitable materials.

It was not easy to find suitable steel for gears in the transmigrator group’s metallurgical department. Moreover, the quality of each batch of steel was slightly different. The result of adopting the principle of using substitutes was that gear tooth breakage accidents occurred from time to time.

Huang Tianyu repaired and gave instructions at the same time. It took half an hour to fix it. He put the damaged gears in a tool bag with a card attached for later analysis. The sweet potato grinder started rumbling again.

The sweet potato grinder was a large machine with an iron axle and a wooden drum. The wooden drum was densely covered with half-inch iron teeth. The grinding blades on top were detachable, so they could be replaced with different sized blades at any time to control the fineness of the sweet potato pulp. This machine looked unremarkable, but thanks to its powerful power support, its processing capacity was 2500 kilograms per hour, a divine artifact in this time and space.

The sweet potato pulp coming out of the grinder had to be washed and sieved. They used a self-made roller screen from the machine factory. The transmigrators were short on industrial filter screens, so they used silk cloth with about 130 holes as the screen cloth.

After sieving, the starch in the pulp flowed out with the water to become starch milk, and the rest was the sweet potato residue. The residue had multiple uses, mainly for producing alcohol. The residue after alcohol production could also be used as fermented feed.

The starch milk could be precipitated to obtain the finished starch product. The precipitation process designed by Jiang Ye for the starch workshop was simple and relatively efficient, using precipitation tanks for separation. The separation tanks were built of bricks and lined with thick “tiles” fired in a Fujian export porcelain kiln. Each tank was 30 meters long and could process 5000 to 7500 kilograms of sweet potatoes every 10 hours.

The starch pulp entering the precipitation tank had to undergo a “pulp matching” process—a traditional Chinese method for making starch. The sour slurry added to the starch pulp was obtained from the natural fermentation of lactic acid bacteria in the pulp during the starch production process. Adding an appropriate amount of sour slurry to the starch milk could promote the rapid coagulation and precipitation of starch. The starch settled quickly at the bottom, while the top layer was a coagulum of fiber and protein, with a clear boundary between the two. This process not only accelerated the separation of starch from impurities but also used lactic acid bacteria to inhibit the activity of other miscellaneous bacteria.

What precipitated out was the starch. The upper layer was a sticky yellow starch containing impurities. The starch in the middle layer was of the best quality. After being dewatered, it became high-grade starch. The bottom layer contained more soil and impurities. It was mixed with the starch from the first layer, and water was added again for another round of precipitation to produce second-grade starch.

Regardless of whether it was high-grade or second-grade, the starch still had a high moisture content when it was taken out—over 50%. It had to be dewatered before it could be stored and used. Zhong Lishi had designed a simple centrifugal dewatering machine for the Leizhou Sugar Company, which the food factory was now using for trials. It could remove about 30% of the water. After drying in the sun or baking, the moisture content of the starch was further reduced to 16%. It was then ground into a powder with a roller, and the finished product could be used in various aspects of food processing and industrial production.

The clear liquid from the top of the precipitation tank was taken out and placed in a water tank to ferment into “old slurry,” which could be used the next day. The remaining wastewater still contained a small amount of starch. The precipitates of crude fiber and protein in the wastewater settled in the wastewater pond to become “sweet potato yellow.” After sieving and precipitating the sweet potato yellow again, the starch could be completely extracted. The remaining sweet potato yellow could be used in the same way as the sweet potato residue.

The entire process and workflow of the starch workshop was designed by Luo Duo. But after it was put into production, everyone realized that the starch factory consumed too much water, and the discharged wastewater contained a large amount of organic matter, which seriously polluted the Wenlan River. For a period, whenever the starch workshop was in production, a section of the river would turn milky white, like rice water. Tian Jiujiu was very troubled by this. Theoretically, the wastewater from the starch factory could be treated by biogas fermentation, but in reality, things were far from simple—after all, this was a factory, not a workshop. For every 100 kilograms of sweet potatoes processed, about 300 kilograms of water were consumed. The amount of wastewater discharged was staggering. Tian Jiujiu had no choice but to continue using sedimentation tanks for primary treatment. The high-concentration wastewater from the sedimentation was then discharged into the biogas digester for fermentation, while the cleaner water from the upper layer was directly discharged into the river.

“This level of pollution can be self-purified by the flow of the Wenlan River during the rainy season, but it’s hard to say during the dry season.”

“It’s fine, let’s just make do for now,” Ma Qianzhu said after reading his report on the wastewater problem. “We can renovate it later when the technical conditions are mature.”

“It’s not just about pollution,” he continued to plead with Ma Qianzhu. “It’s also about the excessive water consumption. To guarantee the water supply for the sweet potato processing plant, the water plant has to be expanded again.”

Of course, Ma Qianzhu did not want to expand the water plant for the sweet potato processing plant. So Tian Jiujiu proposed a new plan: build a water recycling and secondary use system in the food factory. The main idea was to recycle the wastewater generated during the sweet potato washing stage. After sedimentation and simple chemical treatment, it could be reused. It was estimated that this could save 40% of the water consumption.

“Washing with the same dirty water over and over?”

“Of course not. It has to be treated. And it’s not an infinite loop. The water has to be changed after a few cycles.”

The wastewater from washing sweet potatoes mainly contained a large amount of sand, sweet potato skins, and grass leaves. Unlike the wastewater from the later starch process, it contained very little organic matter. Sedimentation could remove most of the impurities, and after passing through a simple sand filter, it could be reused.

However, when Xun Suji came to take over, this system was nowhere to be seen. The dirty water from washing sweet potatoes was directly discharged through the drainage channel under his feet.

“How about it? Interesting, right?” Huang Dashan walked in from outside. Just as Xun Suji was about to introduce himself, he waved his hand, “Mo Xiao’an already told me. From now on, you’re the full-time factory manager here. Now I can finally relax.”

“Yes,” Xun Suji wanted to say a few polite words like “I’ll need your help in the future” and “Mr. Huang, you’ve worked hard,” but he couldn’t bring himself to say them. Huang Dashan didn’t mind and briefly explained the situation of the workshop and production to him.

“The food industry is a big category,” Huang Dashan said. “Since you have a chef’s certificate, it’s considered a professional match.”

“I can make salted duck eggs and pickles, but I don’t know anything about this.”

“It’s fine. You’ll understand after reading a few more books. Isn’t everything here learned from books? Do you think any of us have actually worked in a food factory? Not to mention with such backward processing equipment.”

“This is still backward? It’s the largest starch processing factory in this time and space,” Mo Xiao’an also arrived as they were talking. Xun Suji knew this was his direct superior. He wanted to go up and say a few flattering words, but he had never done this before. Besides calling out “Commissioner Mo,” he couldn’t say anything else.

“Just call me Xiao’an. No need to be so formal.”

This was Mo Xiao’an’s first time here since the starch workshop started operating. His curiosity about this place was no less than Xun Suji’s. He kept looking around.

Mo Xiao’an watched as the slightly yellowish starch was poured out of the centrifuge by the workers, spread on bamboo trays, and prepared to be sent to the drying room for further dehydration. He said:

“This feeling is really strange. They were just oddly shaped, mud-covered sweet potatoes, and in the blink of an eye, they’ve become white starch—” he suddenly asked, “Why isn’t the starch white? It’s yellowish.”

“It hasn’t been bleached,” Huang Dashan explained that in modern starch industry production, starch is bleached. “It’s actually not difficult. You can bleach it with bleaching powder mixed with water. Besides looking better, it’s useless. It adds several more steps, so it’s not worth it.”

“Drain the water!” With a worker’s shout, a huge gurgling sound of water immediately came from the workshop. A large amount of wastewater gushed out of the sweet potato washing machine, instantly filling the workshop’s drainage channel. The current was very strong, and some of it even washed onto the floor. Mo Xiao’an’s trouser legs were soaked.

“You should have worn rain boots to the food factory,” Huang Dashan looked at their shoes and shook his head. He gave a worker some instructions, and soon the worker brought back two pairs of strange boots. They looked like they were made of cloth but were very stiff.

“These are tung oilcloth high-top rain boot covers. You should all put them on. You’ll need them in the workshop later.”

They put the rain boot covers directly on their feet. There was a strap on the instep and another on the calf to fasten them securely, creating a pair of “high-top rain boots.” These boot covers were made of tung oilcloth. The transmigrator group could not supply rubber rain boots at present, and some liquids in industrial and agricultural production were not suitable for direct skin contact, so they came up with this kind of homemade rain boot. The natives often used it together with wooden clogs on rainy days.

Several workers began to take the sweet potatoes out of the washing machine and put them into large baskets. Some were sent to the grinder to be pulped, while the rest were taken to another large machine.

“This is a dual-purpose slicing and shredding machine,” Huang Dashan introduced. “It’s specifically for slicing and shredding sweet potatoes.”

“What’s the use? Can’t they just be pulped directly?” Mo Xiao’an asked strangely. “Are they still planning to make Liancheng dried sweet potatoes…”

Xun Suji thought: is it for drying and preserving?

“It’s probably for making things like sweet potato shred rice,” he said.

Sweet potato shred rice was something Wang Tian had suggested to Wu Nanhai. It was something eaten by the local poor peasants, tenants, and long-term laborers, as well as all frugal landlords and even gentry families. Naturally, this was not a specialty snack, but a means of saving grain.

“The meaning is similar, but the effect is different,” Huang Dashan explained. Slicing and shredding was for easy drying. Dried sweet potato slices and shreds could certainly be stored, but the main purpose here was to grind them into sweet potato powder.

Sweet potato powder is different from sweet potato starch. Besides starch, it also contains the fiber of the sweet potato. It doesn’t taste good when made into food alone, but it can be used as a food filler, mixed into various flour-based foods to pass off as the real thing and reduce production costs, just like how corn flour is widely used as a filler in the modern food industry. As long as it’s not overused, the average consumer won’t notice.

“We don’t have flour now. Otherwise, we could mix it in to make bread, noodles, biscuits, and so on, saving 30-40% of the wheat flour usage.”

“This is even shadier than running a restaurant,” Xun Suji couldn’t help but say.

“There are many dark secrets in the food industry,” Huang Dashan smiled. “Have you ever had maltose?”

“I had it as a child.”

“I sometimes use it when cooking.”

“Maltose is a commonly used raw material in the food industry. But the maltose on the market is rarely made from malt. The vast majority is sweet potato maltose, 5 kilograms of maltose with 100 kilograms of sweet potatoes.”

“It’s a pity maltose can’t be an export product,” Mo Xiao’an was still thinking about this.

“Maltose doesn’t sell for much, and the batches aren’t large.”

Xun Suji remembered his experience as a cook, “I remember sweet potato powder can be used to make vermicelli and flat noodles.”

“Yes, but the vermicelli made from pure sweet potato powder is very brittle and lacks toughness. The taste is far inferior to mung bean vermicelli, so it’s better not to make it for now.”

“What about using it in rice noodles? Mixing a little in would be like mixing it into flour,” Xun Suji remembered. Like in Guangdong and Guangxi, rice noodles were a common food here, whether in soup or dry-mixed, it was a delicacy for ordinary people.

“It should be possible if not used too much,” Huang Dashan considered. “But the food factory has never made rice noodles.”

“Rice noodles are easy to make,” Xun Suji’s spirits rose. “I often made them in the cafeteria. Just take the rice to the mill to be ground into powder, and you can make them.”

“Wait,” Mo Xiao’an remembered. “Aren’t rice noodles an export product?”

“Export dried rice noodles?”

“Yes,” Mo Xiao’an took out a small notebook from his pocket. “Chief Wen said that the mass consumption power in this time and space is low. Most people are in a state of basic consumption, meaning their needs are mostly for food and clothing. I’ve been thinking, dried rice noodles have certain processing requirements, and many people still buy them ready-made and then cook them—”

“There’s no processing difficulty with rice noodles, right? I see that ordinary farming families make them themselves.”

“The focus of dried rice noodle sales should be on the cities, targeting urban residents,” Mo Xiao’an said. “Chief Wen once taught us: since ancient times, the main consumption power of society has been concentrated in the cities. It’s impossible to expect the peasants of this time and space to buy our bulk commodities. In Qing Dynasty Beijing, there were even noodle shops that specialized in making and selling noodles—what technical difficulty is there in making noodles?”

“That’s an interesting point.”

“Dried rice noodles should also have many shops making and selling them in Guangdong, but they can’t compete with us in terms of cost. We can crush them directly with low-price dumping!”

Where did the transmigrators’ cost advantage lie? Mo Xiao’an analyzed that, first, it was the source of rice. The transmigrators used cheap rice bartered for sugar from Vietnam, with batches of dozens of tons at a time. Although there were transportation costs, when spread out, there was still a significant cost advantage.

Second was mixing cheap sweet potato powder into the dried rice noodles, following the modern merchant’s idea of “cutting corners to make cheap products.” It was hard to say how much could be mixed into the dried rice noodles now, but if they could add 20%, the reduction in material cost would be astonishing.

Finally, there was the cost of production. The transmigrator group used large-scale industrial production, and its cost advantage was far beyond what small handicraft workshops could match.

The biggest cost for the transmigrator group was transportation, but now most of the ships returning to Guangzhou from Lincheng were empty. These spaces could be used to transport export products. The transportation cost would not increase much.

All things considered, it was likely that as soon as “Lincheng Dried Rice Noodles” hit the market, the entire rice noodle market in Guangzhou would collapse.

“There’s a flow theory in marketing,” Mo Xiao’an became more and more excited as he spoke. “Just like water, cheap goods have a tendency to spread automatically. We don’t need to do much promotion; the dried rice noodles will quickly expand to all the major cities in Guangdong!”

“And our rice noodles will be cleaner and more hygienic than traditional handmade rice noodles in the processing stage, with fewer impurities. The moisture content will also be lower. With the use of preservatives and other means, both the appearance and the shelf life will be much better than other rice noodles—”

“That’s not a bad idea,” Huang Dashan hesitated. “It’s innovative, but it involves the issue of grain exports. The Executive Committee has a first-level control on grain, and it’s strictly forbidden for export.”

“The import of Vietnamese rice is very large now. The reserves must be very rich.”

“It’s hard to say,” although Huang Dashan’s administrative position was not high, he was in contact with the People’s Commissars of the Executive Committee and heard a lot of internal news. “The Chief has held several meetings on grain work at the Planning Committee recently, and his tone on grain procurement and reserves is still very tight—he’s been talking about a population explosion recently. At this juncture, your plan to export a large amount of rice noodles is probably not going to fly.”

“Really?” Mo Xiao’an was instantly deflated. Thinking about the recent construction of new immigrant villages everywhere, the expansion of the quarantine camp, the 24-hour full-capacity production schedules of the timber processing plant, cement factory, and brick and tile kiln, and the recent orders for clothing and bedding received by the Ministry of Light Industry, all confirmed that this was true.

“Let’s just put the dried rice noodles into production first. After all, they are convenient to store, and they can give everyone a change of pace in their diet,” Xun Suji was not interested in the grand plan of “Lincheng Dried Rice Noodles sweeping the market,” but rice noodles were indeed very popular in the cafeteria. “We can also make instant rice noodles. Think about it, when everyone is hungry, they don’t have to run to the cafeteria to eat.”