Aavi lifted the cooler box lid and a whitish vapour slowly escaped from the box, trickling down slowly. The inside of the box was not visible as a whitish gas filled the entire box, making it impossible to see anything. Aavi poured some of his fizzy drink down into the cooler box and replaced the lid for about five minutes. He lifted the lid again, with wisps of the whitish gas clinging to the lid in a ghostly way. Aavi braced himself before plunging his bare hand into the whitish gas. Instant coldness ambushed his hand sending shiver’s from his fingers all the way to his spine. Aavi pressed on, with him blindly feeling the bottom of the cooler box as if searching for something. His fingers traced over something hard and crystalline, and his fingers closed around this mysterious object. He hauled his prized up rapidly as his hand had already started to feel numb. Aavi triumphantly opened his hand to reveal his treasure and behold, it was the fizzy drink he had poured but in a hardened crystalline form. Now that Aavi’s hand had returned to it’s normal body temperature, the crystal felt cold. Aavi placed it on his case, he would treasure it for ever… It melted five minutes later, that was Aavi’s first heart break.
What’s up my young Uchiha’s, it’s Aavi here, I mean Aavi Yadhav Uchiha Singh. Anyways, I wanted to do something food related again, so I browsed through the Food Tech News Feed which is so hard to find and came across a familiar topic, that is Liquid Nitrogen. The memory above is from the Grade Ten Physics Tuition, and let me just say that those tuitions helped big time. They were held at the UKZN campus by Dr. Meghendren Govender, an eccentric, brilliant scientist… who’s also quite attractive. I had to eventually stop going as it was too far…. (My physics grades were never that good again, except maybe at campus.)
Pressing on, if you haven’t already figured it out, Liquid Nitrogen was the “chilling whitish gas” in the cooler box. So if you’re like me, you’re probably dying to know more about this interesting gases as well as it’s uses.
Liquid Nitrogen is basically another form of Nitrogen, another phase of matter if you will. As you may well be aware, Nitrogen is a gas that makes up about roughly 80% of our atmosphere, although that figure is constantly changing as the years go by. I guess you could compare Nitrogen gas to being the equivalent of a “wallflower”. I say that because the properties of Nitrogen gas make it almost undetectable by human senses. It is non-flammable, non-toxic, inert to most chemicals and environments. It also has been stated that it is not a gas that will support life, or human life at least.
I mentioned phases of matter before, and that is essential to understanding what liquid Nitrogen is. Matter is what everything in our universe and world is made up of and it has mass and takes up space , and matter can exist in three accepted states, that is solid, liquid and gas. Water as we know can exist in all three states, ice as a solid, water as a liquid and water vapour or steam as a gas. At room temperature water is a liquid, at colder temperatures , water is ice and at higher temperatures, water is transformed into steam. Similarly, when Liquid Nitrogen is cooled below it’s boiling point of -196 degrees Celsius, it is condensed to a liquid form so to speak. This liquid appears to be white upon rapid heating or sudden contact into higher temperatures.
Liquid Nitrogen has a multitude of uses across many industries and the food industry is no exception. As you well know, I’m extremely lazy so for the sake of this blog, I’ll focus on the most known and used applications of Liquid Nitrogen in the Food Industry, mainly freezing and mixing.
Cryogenic (i.e., very low-temperature) freezing results in smaller weight losses from dehydration than traditional mechanical freezing. Dehydration in this case is the loss of water/moisture. The importance of moisture in food products is well emphasized because significant increases or losses, as in this case, can lead to deterioration of food quality or increased vulnerability of food spoilage micro organisms. Loss of food quality can include shriveling of food, textural changes, unsightly appearance and nutritional changes. Vulnerability to food spoilage micro organisms can vary due to other factors such as temperature and storage conditions, but it still means it is a micro risk to microbes like bacteria and fungi.
Frozen food processors can thus preserve the quality of their products with a freezing system that uses environmentally friendly liquid nitrogen. However Frozen food processors must regulate the volume and quantity of Liquid Nitrogen as even the most harmless gas can become dangerous if it is over saturated. A good example would be like if your body was over saturated with solely oxygen. Therefore moderation is key in these kinds of processes.
Due to its own extremely cold temperature, liquid nitrogen can enable a cryogenic system to freeze food within minutes, instead of the hours traditionally required with other systems. The faster freezing causes the formation of small ice crystals, which then help ensure product moisture and quality are maintained longer. You may wonder why smaller ice crystals are preferred over larger ice crystals ? It’s because smaller ice crystals cause less cellular damage and therefore there are less textural changes to the point of it being negligible.
Further, liquid nitrogen can be used to remove heat from other processes to help prevent microbial growth, reduce cycle times, and/or increase production throughput. For example, Excellent Foods in Burbank, Wash used a liquid nitrogen freezer for its Apple Fries products. These peeled, cut, coated, deep-fried, and finished apple wedges needed moisture locked in before going to market. With an immersion tunnel system, they took only three to four minutes from peel to freeze. This is cost saving and helps to ensure that production moves at a rapid pace meet production goals and reduces external processes that were previously needed and costed valuable production time.
Other companies over the years have recognized and acknowledged the value of cryogenics. Custom Pack in Biloxi, Miss, switched over the years from canning shrimp to a variety of freezing techniques, including the use of a cryogen straight tunnel freezer for a time. Eventually, the company settled on cryogenic technology with a nitrogen-based immersion freezer to process individually quick-frozen (IQF) shrimp. This proved particularly well-suited for the wet and fleshy seafood. As a result, production capacity increased from 5,000 to 8,000 pounds per hour. Holten Meat in Suaget, began using liquid nitrogen freezing tunnels in 1974. The technology allows the company to ship its frozen Thick N’ Juicy hamburger patties and maintain their freshness 90 days from code date, providing a much longer shelf life than fresh patties.
Mixing, coating, and grinding
In mixing applications, liquid nitrogen is used to chill sauces and gravies to stop the cooking process while reducing cool cycle times. In coating applications, the low temperature of liquid nitrogen allows it to enrobe individually quick-frozen (IQF) products in sauces while they freeze, helping produce an even coating. During grinding, meanwhile, liquid nitrogen can be used to eliminate frictional heat to help improve the throughput of mills, while also preventing the loss of flavour and aroma components in food additives, ingredients, and functional foods.
Specialized equipment can be coupled with liquid nitrogen to help optimize IQF and non-IQF food freezing, crust freezing, chilling, coating, mixing, and forming. Regardless of size, both the equipment and the nitrogen can be configured in a mode that matches the scale of the food processing operation.
Such a fascinating liquid right? What could go wrong, well….
Yeah, sadly there are hazards associated and not fully appreciated regarding Liquid Nitrogen. It has two major life threatening hazardous properties. Firstly, because the liquid can evaporate very quickly, it can effectively displace air to create an atmosphere that is unable to support life. Secondly, it can cause injury from the intense cold of the liquid.
Asphyxiation (oxygen deficiency)
On evaporation, liquid nitrogen produces about 680 times its own volume of gas. If this occurs in an enclosed area that is inadequately ventilated, atmospheric oxygen will be displaced by the nitrogen. Eventually the oxygen concentration may become so low that the atmosphere will not sustain life. Anyone in such an environment will become unconscious and will quickly die unless remedial action is taken.
Persons working in an atmosphere that is becoming oxygen deficient are unlikely to be aware of the increasing danger, as there are few warning signs. Those signs that may be present (e.g. increased frequency and depth of breathing and raised pulse rate) are masked by impaired perception and judgement resulting from the reduced oxygen levels. Often the first indication that anything is wrong comes too late to allow any response to the situation. Also when persons enter an area in which the oxygen concentration is severely reduced they may become immediately unconscious. It is therefore vital to ensure where these risks may be manifested.
Multiple fatalities have occurred when rescuers have themselves been overcome while attempting to assist an unconscious colleague. The temptation to enter an area to effect a rescue is strong. However, the risks of doing so are extremely high. It is essential that emergency action is planned in advance and that staff are trained to understand the action to be taken in such circumstances. enter an oxygen deficient atmosphere unless they are wearing suitable breathing apparatus and are trained in its use.
Cryogenic (cold) burns
Liquid nitrogen is kept at ‘cryogenic’ or very low temperatures –196 degrees Celsius below. Contact with liquid or vapour at such temperatures can produce damage to the skin and other tissues. The effect is similar to a burn. Delicate tissues such as that of the eye, is damaged more easily and prolonged exposure can lead to frostbite.
Contact with non-insulated parts of equipment or vessels containing liquid nitrogen can produce similar damage. Moreover, unprotected parts of the skin may stick to low temperature surfaces as, the moisture of the skin becomes frozen. Thus extreme care must be taken as the flesh can be torn away whilst trying to break free. Inhalation of cold vapour can cause damage to the lungs and may trigger an asthma attack in susceptible individuals whilst prolonged exposure to low temperatures can induce in generalised hypothermia.
Recent FDA Warning Against Liquid Nitrogen in Food Products
On the 31 August 2018, the FDA issued a warning to consumers and retailers alike of the potential risks and harm as a result of consuming or interacting with foods that have been prepared with Liquid Nitrogen at the point of sale, or immediately before consumption. The products that are guilty of such harm include products such as Dragon’s Breath and Nitro Puff. I tried looking up these food items online and I must say, I had little luck finding any results. I’m assuming that’s how bad the back lash was from these products.
Due to the influence of Liquid Nitrogen it would cause consumers severe damage to their skins as well as to their internal organs. There were reported cases of consumers suffering from asthma attacks and drops in body temperatures. Some situations were just an injury whilst other situations required serious medical attention and hospitalization. I believe that for now, Liquid Nitrogen should only be added to products during the processing, as addition to foods during time of consumption is too risky. For now Liquid Nitrogen should serve as a processing aid in Food products, whereby it has no significant effect on the final product.
The ideal situation for Liquid Nitrogen being added to food stuffs at point of sale would be to have it evaporate quickly before it reaches the consumer. However, it is consumers themselves who wish to consume products with the Liquid Nitrogen still intact, as they find it to be visually pleasing. Liquid Nitrogen may be one of the trendiest substances both on social media like Instagram and Facebook, but just be careful it’s more risky than it is trendy…. (Didn’t stop me from “smoking” it though).
So for now that’s it my young Uchiha’s, and I’ve attached a video link so this blog does not end on such a bad note. (Couldn’t upload video, as I don’t have premium version).
Ciau from Aavi and Lord Sri Krishna.