Can you eat pistachio shells?

In this article, I will answer the question: “Can you eat pistachio shells?” and I will provide information about potential dangers. On the other hand, I will briefly describe the health benefits of these nuts and amazing ideas to include them in your daily diet.

Can you eat pistachio shells?

The answer is no, you can’t eat pistachio shells. While pistachios are nutritious and healthy, their shells are fibrous, difficult to chew, and cannot be digested. It’s better to get unshelled pistachios to get the most out of them.

Why are pistachios sold in their shells?

Producers must remove the protective shell from nuts like walnuts and cashews before roasting and salting them. But why is this not the case with pistachios? Pistachio has to be processed within 24 h after harvest to avoid hull-trapped moisture, which causes staining of the pistachio hard shell (1). 

Once Pistachio Nuts are harvested, the hulls should be removed and the pistachios must be dried immediately to decrease their moisture content from 40–50% to 4–7%, which are considered the optimum values to avoid fungal proliferation (2).

According to the University of California, between 70 and 90 percent of pistachios acquire a natural split in their shells throughout the developing process. Pistachios may be salted and roasted while still inside the shells after being shaken off the trees by harvesting machinery, as that natural crack gives heat and salt access to the nut, removing a step in the industrial process and saving processors costs.

When pistachios arrive at the processing plant, the following procedures are conducted: (a) dehulling, to separate the soft hull from nuts; (b) trash and blank separation, to remove blank pistachios and trashes such as small branches, remaining shells and leaves; (c) unpeeled pistachios separation, to remove unpeeled and unripe nuts; (d) washing, which involves spraying water at high pressures on the pistachios to clean the nuts; (e) drying, to decrease moisture content of pistachios from 37 to 40% to the appropriate level; (f ) split nuts separation, to separate split nuts from non-split ones; (g) salting; (h) roasting; and (i) packaging. During the drying process, nuts can undergo undesirable reactions (especially rancidity) which cause degradation of quality, because of the odd colors and flavors formed. The major oxidative reactions in dried foods are due to peroxidation of lipids (3).

The larger pistachios are usually those that split spontaneously. Only a small percentage of nuts that do not split on their own are subjected to industrial shell-removing processes. Some experts believe unsplit nuts are less ripe than split ones.

The majority of the unshelled pistachios are used in cooking and in items like pistachio ice cream. The use of pistachios as an ingredient in recipes is becoming increasingly popular.

It’s worth noting that pistachios without shells are twice as costly as those with shells.

What happens if you eat pistachio shells?

Pistachio shells are not suitable to eat since they are difficult to digest and chew. Attempting to chew and swallow the shells might cause damage to your mouth and digestive tract.

Furthermore, the digestive system is unable to break down these shells, preventing any nutrients from being absorbed by the body. Imagine spending time chewing something that isn’t going to benefit you while also risking injury. A study showed that pistachio hulls have a high content of bioactive compounds (such as polyphenols, tocopherols, dietary fibers, essential oils, and unsaturated fatty acid) with antioxidant properties and health-promoting effects. However, this residue should be a source of extractable compounds and not be directly eaten and, in order to be used, it must be turned into a fine powder and (1).

Instead, eat your pistachios and save the shells for other uses.

What are the health benefits of pistachios?

Pistachios have earned a reputation as a guilt-free snack high in unsaturated fats, fiber, and antioxidants that are good for you. Within fatty acids,oleic and linoleic fatty acids,both recognised for their cardiovascular-preventive properties, represent more than 60% of the total fat content in pistachios (4).

Pistachios may help to lower blood pressure and stimulate the growth of good gut bacteria, according to research. Pistachios are a good source of vegetable protein,which comprises about 20%of total weight,with approximately 2% L-arginine.This amino acid, also present in other nuts, is a precursor to the endogenous vasodilator NO, an important molecule involved in the cardiovascular system as a key regulator of vascular tone and in numerous pathological conditions such a hypertension, CVD and neurodegenerative disorders due to its pro-oxidant capacity (4).

They’re even gaining a reputation as a weight-loss nut, partly because, like other nuts, they make you feel full, and partly because the extra effort required to crack and extract their shells slows down consumption.

In a 2011 study, participants who had to remove the shells off pistachios consumed 41% fewer calories than those who were given pistachios with the shells already removed. Specifically, visual cues may decrease the amount of pistachio nuts consumed, by allowing the consumer to see what they have already eaten (5).

What are other uses of pistachio shells?

Since you can’t eat pistachio shells, there are some creative ways to use it (6):

  1. Mulch:

Mulch is a layer of basic materials (compost, decomposing leaves, bark, etc.) placed to the soil’s surface. Mulch increases the soil’s fertility, health, and weed development. Mulch not only improves the health of your farm, but it also enhances its aesthetic appeal.

You can either apply your pistachio shell directly to the soil surface or mix it with other organic mulch before applying it. When broken down, pistachio shells add carbon, lipids, glucose, and protein to your soil. To prepare the shells, soak them in water overnight and then place them in the soil the next day.

  1. Fire kindling:

Pistachio shells are excellent for kindling in enclosed fire pits and wood stoves. The texture, oil content, and air gap in the shell make it ideal for setting a fire. You might want to avoid using this shell for an open campfire because the oil component in it causes it to explode when exposed to high open fire temperatures.

If you must use it for an open fire, wrap it in paper first before lighting it. This will keep them from bursting in the flame.

  1. Drainage for Potted Plants:

Pistachio shells can also be used as drainage pebbles at the base of potted plants. Small rocks and pebbles are common materials for potting drainage; nonetheless, pistachio shells offer advantages compared to these materials.

One of the benefits of using pistachio shells is that they biodegrade, so you won’t have to take them out when it’s time to re-pot, and they’ll also protect your plant from being waterlogged. Drainage from the pistachio shell is also beneficial to the root system.

  1. Pest deterrent:

Pistachio shells help keep pests away. Spread the shells throughout your garden to cover the soil and deter animals such as chipmunks, cats, squirrels, and raccoons from digging in it. Slugs and snails will also flee if your shells are salted. Simply spread the shells near the plants of your garden.

  1. Composting:

Pistachio shells can be used not just as mulch, but also as compost. Gather them in large quantities and allow them to degrade; you may also combine them with other compost piles. It’s possible that this will take a long time, perhaps eight to twelve months.

Other FAQs about Pistachios that you may be interested in.

How to tell if pistachios are bad?

Can pistachios go bad?

How to cook pistachios?

Conclusion

In this essay, I answered the question :“Can you eat pistachio shells?” and explained why it is not suitable to consume them. I also gave creative ideas to use them for gardening and other applications.

Please contact me if you need any further information about this subject.

References

  1. Arjeh, Edris, et al. Bio-active compounds and functional properties of pistachio hull: A review. Trend Food Sci Technol, 2020, 97, 55-64.
  2. Sena‐Moreno, Estela, et al. Drying temperature and extraction method influence physicochemical and sensory characteristics of pistachio oils. Euro J Lipid Sci Technol, 117, 684-691.
  3. M. Kashani Nejad , L. G. Tabil , A. Mortazavi & A. Safe Kordi. Effect of Drying Methods on Quality of Pistachio Nuts. Dry Technol, 2003, 21, 821-838
  4. Bulló, M., et al. Nutrition attributes and health effects of pistachio nuts. Brit J Nutr, 113, S79-S93.
  5. Kennedy-Hagan, Karla, et al. The effect of pistachio shells as a visual cue in reducing caloric consumption. Appetite, 2011, 57, 418-420.
  6. Fallahzadeh, Reza Ali, et al. A Review of Strategies for Using Pistachio Waste. Pistach Health J, 2021, 4, 86-95.