Sweet corn cobs processing machines and vacuum packaging machines

precooked corn cobs vacuum packaging machine

This article introduces the common processing technology for precooked sweet corn cobs, and related processing machines, vacuum packaging machines, from small scale production to massive production.

We are hoping you can get an overview impression of sweet corn cobs processing and packaging after reading this article. It would be great to be helpful to your sweet corn business.

Sweet corn introduction

Sweet corn is a naturally occurring genetic variant of field corn that allows kernels to store more sugar than field corn.
According to NASS 2020, the total value of the sweet corns harvested in year 2016 was nearly $9 million, around 70% of which was produced for the fresh market and 30% for the processing market. Processing sweet corn production (both frozen and canned) in 2015 totaled 2.5 million tons with a crop value of $255.5 million.

Fresh sweet corn has the genetic characteristic of inhibiting the conversion of sugar to starch. Compared with ordinary corn, sweet corn has obvious differences in the content of starch, sugar, protein, fat and vitamins. The protein content of sweet corn fresh kernels is more than 13%, the sugar content is more than 10%, and the crude fat content is about 9.9%. Every 100g of sweet corn contains 0.7mg of vitamin C, 0.22mg of niacin and vitamin B2, and 1.70mg of riboflavin and vitamin B2. . In addition, sweet corn also contains a variety of volatile aromatic substances, minerals, dietary fiber, oryzanol, sterols and other ingredients.

Sweet corn cobs processing and vacuum packaging

Vacuum packing is one of the common technology for sweet corn cobs processing and preservation. Of course, food packaging is not an isolated process, it’s strongly combined with the processes of harvest, cleaning, cutting, precooking, sterilization, freezing and final storage. Each processing step plays a vital role in the final storage quality and the shelf life of sweet corn.

Work flow

Please kindly understand that there are many processing technologies for sweet corn cobs, we are only presenting one of them here.

  • Sweet corn ear harvest
  • Preprocess (Remove husk and silk, cut and trim, cleaning and grading)
  • Blanching
  • Cooling
  • Vacuum packing
  • Sterilization
  • Package bag drying and cleaning
  • Inspection and storage

Sweet corn ear harvest

Choose sweet corn in the milky maturity period (18-20 days after pollination) to be harvested in the morning of sunny days, leaving (2~4) husks. Fresh sweet corn ears must not be thrown on the ground at will, or severely bumped or squeezed during loading and unloading and transportation, after being picked up according to the requirements of the harvesting standards. They must be handled with care to reduce losses and increase the yield. It is required that the corn ears are free of insects, the kernels are arranged uniformly and neatly, rich and full. The corn ears with insects can still be used as raw materials after trimmed to meet the requirements.

sweet corn cobs vacuum packaging machine

Sweet corn cobs preprogress

The harvested sweet corn ears should be protected from exposure to the sun and rain, and delivered to the processing plant at low temperature in time (within 12h).

Remove husks and silks with care. There are several types of automatic husks remove machine for corn ears, with different capacity and prices, y ou can try to search and choose according to the scale of your production.

Trim the corn ears to unified length, manually or use automatic specially designed corn cobs cutting machines.

sweet corn cobs cutting machine

Clean the corn ears with clean water, manually or use Inline brush roller water-spray washing machine.

sweet corn cobs washing machine

Sweet corn cobs blanching

Add 0.1% citric acid and 1% salt to the blanching water, the temperature is 95°C-100°C, and the time is 5-12 minutes, so that the corn cob core temperature reaches 95°C or higher. It can also be blanched with steam。.

The main purpose of blanching is:

  1. It softens the tissue, removes the air in the tissue of the tender corn, reduces the pressure formed by ice crystals during freezing, and correspondingly reduces the degree of oxidation of the raw materials, so as to help maintain the color and nutrition of the product.
  2. Blanching destroys enzyme activity, stabilizes color, improves flavor and organization, and prevents the nutrients in the sticks from being destroyed.
  3. Blanching removes part of the water in the sweet corn and keep the solids stable.
  4. Blahching kills some of the microorganisms in the corn cobs, reduces the number of pathogenic bacteria, and lays the foundation for improving the bactericidal effect.
sweet corn cobs vacuum packaging machine
Blanching Machine

Sweet corn cobs cooling and drying

After blanching, the ears of corn must be cooled in time, otherwise the corn kernels will lose water and wrinkle due to high temperature, which will affect the appearance and quality of corn. Generally, spray with clean water or soak in cold water for 3-5 minutes to lower the surface temperature of the ears to ensure that the temperature of the ears is about 50°C during bagging.
On the contrary, if the temperature of the corn ear is too high, the moisture will evaporate during the vacuum packaging and produce steam, which will adversely affect the quality of the vacuum packaging.

Drying the corn cobs on an automatic drying machine before moving to the step of vacuum packaging.

corn cobs drying machine

Video of sweet corn cobs cutting, washing, blanching, cooling and drying

YouTube video

Sweet corn cobs vacuum packaging machines

After blanching and drying, the corn cobs are ready to be vacuum packed. According to the production capacity and type, Yide Machinery introduces 5 types of sweet corn cobs vacuum packaging machines.

Vacuum pack sweet corn cobs in premade vacuum bags

sweet corn cobs vacuum packaging machine

Vacuum pack pre-cooked sweet cobs in premade vacuum bags is one of the major packaging type. The vacuum bags are usually retort pouches that is high-temperature resistant and high-barrier.

According to the production capacity, there are several vacuum packaging machines to choose, including single chamber vacuum sealer for small scale production, double chamber vacuum packing machine and belt-type continuous vacuum packaging machine for medium to large scale production, and rotary premade pouch vacuum packing machine which is automatic and requires minimum labor cost.

Video: Belt-type continuous vacuum packaging machine for vacuum packing of corn cobs in premade vacuum bags:
Speed: Around 1000 ears per hour
Bag filling: Manual filling
Labor cost: 1 operator for each machine, and staffs for bag filling

YouTube video

Video: Rotary premade pouch vacuum packaging machine for vacuum packing of corn cobs in premade vacuum bags:
Speed: Around 2000-3000 ears per hour
Bag filling: Semi-autoamtic filling, fast speed
Labor cost: 1 operator for corn cobs filling

YouTube video

Precooked sweet corn cobs vacuum packed by thermoforming packaging machine

Thermoforming packaging machine is the fastest vacuum packing method for precooked sweet corn cobs.
Speed: 1500-5000 Packs per hour, according to machine size.
Product loading: Manually
Labor cost: 1-2 staff for each machine

YouTube video

How to choose precooked sweet corn cobs vacuum packaging machine

  1. It depends on what packaging type you prefer, in premade vacuum bags, or thermoforming packaging.
  2. If you choose premade bags packaging, the next consideration is budget. Single chamber vcuum packaging machine costs USD 1000-2000; Double chamber vacuum packaging machine costs USD2000-8000; Belt-type continuous vacuum packaging machine costs around USD8000. These 3 types of vacuum packaging machines are lower cost, but needs at least 1 staff to operate the machine the other staff to fill in the vacuum bags;
  3. The rotary premade pouch vacuum packaging machine requires only 1 staff to load the corn cobs, but the machine cost is higher, about USD 45000 – 60000.
  4. If you want the highest vacuum packing speed, thermoforming packaging machine seems to be the best choice. According to  your requirement, the mold is designed uniquely, which may contain 4 PCs corn cobs or 12 PCs corn cobs, whcih results in different packaging speed, from 1500 packs per hour to 5000 packs per hour.
  5. The cost of the thermoforming packaging machine are thus different, a smaller machine may cost around USD36000, while a large machine costs around USD 55000. Please keep in mind that you need compressed air for the machine to work properly. And inkjet is necessary is you want to print date information on the packages.

If you are not sure which machine to choose, feel free to contact us for an advice.

High temperature sterilization

Before sterilization, check whether the sealing meets the standard requirements. The qualified packaged products are sent to the autoclave for high temperature sterilization. The sterilization formula is 15′-20′-20’/121°C, that is, it takes 15 minutes to make the temperature in the sterilization tank reach 121°C, and keep the temperature constant for 20 minutes. During this period, the pressure in the sterilization tank must be kept stable, otherwise the bag will be broken. Because the moisture in the packaging bag expands when heated. In order to prevent bag breakage, back pressure cooling should be used, and the pressure should be higher than the sterilization pressure by 0.02-0.03 MPa. The cooling time is 20 minutes and the temperature drops to 40°C.

precooked sweet corn cobs vacuum packaging and sterilization
Autoclave sterilizer retort for corn cobs

Packages cleaning, drying and storage

Use automatic cleaning and drying line (air blower dryer machine) to clean and dry the packages, meanwhile, check the vacuum packing quality, check if there’s any air leakage and broken bags.

Storage the vacuum packed sweet corn cobs in room temperature environment, shelf life can be 6-12 months.

air blower dryer after the corn cobs are sterilized in autoclave

Dry the corn cobs vacuum packages after sterilized in autoclaves

Video for the whole process

There could be many processing technology for sweet corn cobs and other species of corn cobs, and the processing machines might also be different. Here we present 1 of the possible processing technologies you might be interested in.

YouTube video


Processing and vacuum packaging of precooked sweet corn cobs requires attentions to several critical points including:

  1. Quality of raw sweet corn. The basic factors that determine the edible and processing quality of sweet corn are the sugar content and water-soluble polysaccharide content of the kernels. Polysaccharide is a kind of multi-branched small molecular starch, which can be dissolved in water and has a waxy taste. It is one of the main factors that constitute the flavor of sweet corn. The tenderness of the peel is also one of the factors that affect the taste. Therefore, when corn is harvested, it is necessary to determine that the above three factors of sweet corn are in the best state according to observation and research.
  2. Blanching time. On the one hand, blanching can inactivate the various enzymes present in the ears of sweet corn, so that the nutrients in the body will not be destroyed, and can effectively prevent the color change (the kernals might turn purple is not properly cooked) and prolong the storage period; on the other hand, it can kill the adhesion in the field. The microorganisms and insect eggs on the surface of the ears ensure the sanitation and edible safety of processed foods; it can also squeeze out the air in the tender corn tissue, increase the resistance to expansion pressure, and reduce the damage rate during sterilization; correspondingly reduce the oxidation of raw materials To a certain extent, it is conducive to preserving the color and nutrition of the product, and makes the ears of sweet corn have a sense of cooked food.
    The formation of sweet corn flavor mainly depends on the degree of gelatinization of amylopectin in the endosperm of the pre-cooking stage. Only after all gelatinization, the sweet corn taste can be obtained, and the same flavor quality can be maintained after sterilization. However, if the gelatinization is not good, the amylopectin cannot be further gelatinized during sterilization. Make the product unsuitable for consumption. If the pre-cooking time is too long, the corn kernels will crack and the flavor will decrease. Therefore, we use its flavor, palatability, and grain cracking as indicators for comprehensive evaluation to determine the blanching time.
  3. Sterilization. For most vacuum packages, through and in-time sterilization is the key to prolong the shelf life.

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