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Circular Screener Improves Soy Concentrate Process

RICHMOND HILL, ONTARIO—Pak Fok Food Products, Inc., improved the flavor, texture and "mouthfeel" of soy milk concentrate while increasing production rates tenfold in a newly designed plant that is automated, energy efficient, and waste-free.

The unique process, designed by Simon Kwan, owner and president, produces concentrate that is whiter, more neutral and free of "beany" flavor considered undesirable in soy beverages.

Smooth mouthfeel, a key attribute, is achieved by removing particles larger than 118 microns (.00465 in.) from the juice extracted from crushed soy beans using a 48 in. (122 cm) diameter Kason VIBROSCREEN® circular vibratory screener.


Producing soy concentrate

Producing soy concentrate at the new plant involves: de-hulling the soy beans; washing, hydrating and crushing them into a slurry; and extracting, filtering and pasteurizing the juice prior to chilling and shipping the concentrate.

In researching methods to improve the extraction and filtration/separation stages of the process, Kwan found that a circular vibratory separator could screen to 118 microns at 6000 l/h (1584 gal/h).

In the former plant's extraction process, a dual rotary drum filter, followed by a filter press, removed most of the solids from the slurry. A Kason 30 in. diameter screener separated the balance of the solids to 75 microns. But the flow rate was limited to 600 l/h (158 gal/h).

A new extraction process increases the flow rate tenfold while increasing viscosity of the feed. The screener accommodates this volume after a switch to a tough "market-grade" stainless steel wire mesh that can be highly tensioned to increase shear, and by optimizing the screener's vibration and discharge pattern according to the flow characteristics of the soy solution—a service performed by Separator Engineering, Ltd., Scarborough, Ontario, the Canadian affiliate of Kason Corporation.


Screening the slurry

The circular vibratory screener is equipped with an imbalanced-weight gyratory motor positioned beneath the screening chamber. The motor imparts multi-plane inertial vibration to the spring-mounted screening deck, causing oversize particles to vibrate across the screen in controlled pathways to the screen periphery where they are discharged. Undersize particles pass rapidly through the screen and fall through the bottom outlet.

Protein and agglomerates clogging the screen are cleared once per hour using a clean-in-place (CIP) system that sprays hot water multi-directionally through perforated, ball-shaped spray nozzles positioned strategically within the screening chamber. The entire screener is manually disassembled every 24 hours for thorough wash down.

Eliminating waste

The new process is fully automated, requiring only two operators, and is environmentally friendly. The plant receives soybeans from railcars, eliminating packaging waste, and sells the "Okara" soy bean by product discharged from the extractor and screener (consisting of agglomerates, protein, undissolved sugar and fiber solids) as an ingredient for Asian-style soups, vegetable dishes and tofu, and as animal feed.

The plant also conserves energy by reusing process water and recycling heat energy consumed in various stages of the process.

The soy concentrate ultimately is diluted to produce soy milk, other soy-based beverages, and other soy food products.

Circular Screener Improves Soy Concentrate Process
 

Soybeans are de-hulled, washed and crushed after which juice is extracted, screened, filtered, pasteurized and chilled. The fully automated plant requires only two operators and produces no waste.


Circular Screener Improves Soy Concentrate Process
 

A 48 in. (122 cm) diameter circular vibratory screener from Kason Corporation removes particles larger than 118 microns from soy juice at the rate of 4800 l/h (1267 gal/h).


Circular Screener Improves Soy Concentrate Process
 

Particles larger than 118 microns are removed from soy juice using a tough, market-grade stainless steel wire mesh that can be highly tensioned to increase shear. The screener is cleaned hourly using integral clean-in-place nozzles, and disassembled (as shown) for thorough wash down every 24 hours.