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Genetically Modified Apples ~ Ever Fresh & Never Brown? Part 1

Daniela Rambaldini Article by: Daniela Rambaldini
Genetically Modified Apples ~ Ever Fresh & Never Brown? Part 1

2013.11.08: UPDATE! The US Department of Agriculture is asking for public comment on a risk assessment of the Genetically Modified Non-Browning Apple. Please take the time to opine on this important ecological and public health issue.

What are genetically modified apples? It's GMO awareness month, which means the public cry against Genetically Modified Organisms (also called Genetically Engineered Organisms, abbreviated as GEOs) is in full tilt. It's therefore an appropriate time to let Canadians know that their beloved apples are also under threat of becoming unnaturally manipulated in the lab. In this 6 part blog series, I will detail the reasons for and against the proposed new breed of this delicious pomaceous fruit.

Part 1:

In Part 1 of this blog series, I'll introduce the premise upon which a Canadian company recently applied to Health Canada and the Canadian Food Inspection Agency for approval of commercially producing a genetically modified apple (GM apple).

First, A Bit About Apples

Apples are an important commercial crop—among the most important in temperate climate zones. Every year, more than 60 million tonnes of apples are produced globally. They’re an appealing natural food, and their popularity is well deserved! There are so many reasons to love apples; they:

- taste delicious and pack an incredibly juicy crunch
- are dense in nutrients
- grow easily under a wide range of soil and climate conditions
- are versatile as a culinary ingredient
- can be easily stored for extended periods of time
- come in several varieties, each with their unique flavour and texture
- boast many health-supporting properties.

In addition to being high in the insoluble fibre known as pectin, which helps to stave gastrointestinal and cardiovascular diseases, and being a rich source of the essential trace mineral boron, which supports memory and other brain functions as well as bone strength and insulin activity, apples are also extremely rich in valuable phytonutrients known as polyphenols.

Polyphenols show a wide range of beneficial effects on human health. They have anti-cancer, anti-inflammatory, and antioxidant properties. They may also help promote healthy longevity. In one study, a polyphenol extracted from apple showed life-extending effects on yeast by promoting the expression of an anti-aging gene. Preserving the polyphenol content of apples during harvesting, storage, and processing is important for the food industry and for maximizing the health-promoting effects of apples.

Understanding the Chemistry of Apple Browning

Enzymes known as polyphenol oxidases (abbreviated as PPOs) break down polyphenols. PPOs are abundant in apple flesh and are located within cell structures called plastids. When apples suffer any form of physical trauma (such as cutting, bruising, biting, etc.), cells are lysed (broken) and PPOs are released from plastids.

When PPOs come into contact with polyphenols, they degrade them into substances known as o-quinones, which eventually react with minerals, amino acids, or proteins to form brown pigments (known as melanoidins). This process is known as immediate enzymatic browning and it’s the cause of the characteristic discolouration of damaged or processed apples. Peroxidase (PODs) and tyrosinase enzymes may also be minor contributors to the browning process.

The Economics of Apple Browning

Preventing browning of apples is important in the food industry. Various conventional and nonconventional methods have been employed to protect apples from the cosmetic discolouration, tissue damage and nutritional degradation caused by enzymatic browning (See Table 1).

Silencing the expression of PPO genes prevents the PPO enzymes from being produced in the cell. Therefore, when the apple is cut or endures physical trauma, the ruptured plastids don't release the PPO enzymes. This halts the degradation of polyphenols into melanoidins and prevents the apple tissue from browning. PPO gene silencing involves genetic manipulation of an apple cultivar, and thus it’s an invasive procedure.

Recently, a fruit growing company called Okanagan Specialty Foods (abbreviated OSF) based in Summerland, British Columbia, applied to Health Canada and the Canadian Food Inspection Agency for approval of a genetically modified apple (GM apple) that intrinsically doesn’t brown because the PPO genes have been silenced. The new development has created controversy within the local growers community and amongst consumers and anti-GMO activists.

In Part 2 of this blog series, I will give a brief background of what it means to genetically engineer an apple and I debunk the OSF's claim that GM apples safer than other GMOs.

Look for the Non-GMO Project logo throughout the vitarock.com website to buy GMO-free certified foods and products such as those recommended below.

You can download a .pdf of the article in its entirety, including references, at the bottom of this page.