Summary and Overview:
Extraction and Storage of Raw
Juices While Retaining Nutrient Quality


by Vinny Pinto, MA*

Introduction

This document will provide an overview and summary of what we currently know about juicing of fresh raw vegetable juices and storage of these juices under refrigeration, in light of concerns about possible degradation of nutrient quality.  Some hints and opinions will be provided regarding which type of juicer to use, how to best store juice under refrigeration and how long it seems to last before serious degradation of nutrients occurs.
 

Background

There has been some speculation in the raw foods world for at least several years regarding the viability of fresh raw vegetable juices, namely: for how long after juicing do the juices retain maximal or near-maximal nutrient value?  Nutrient value has usually been informally defined as preservation of important nutrients in the juice, including vitamins, enzymes, proteins and complex carbohydrates, and including numerous plant substances found in juices which may be poorly-identified and enumerated by scientific researchers to date.  The largest single source of degradation in a raw fresh juice (as well as most other raw foods) is oxidative degradation due to a family of so-called free radicals known as reactive oxygen species (ROS), which include peroxide ions, superoxide anions, and other aggressive oxygen species, including O3 and other short-lived oxygen radicals.  It is well known that the degree of exposure during juicing of the juice to heat and ambient air containing oxygen, particularly tiny bubbles of oxygen which are finely dispersed (as in repeated grinding, blending or mastication), can rapidly accelerate the formation of these ROS components, and thus, rapidly accelerate aging of the juice and its nutrient quality.
 

Some Guidelines on Juicing

It has long been acknowledged that the method of juice extraction greatly affects juice quality. As noted above, methods which involve excessive heating, grinding, or mastication tend to rapidly accelerate ROS processes, and therefore, degradation.  Regarding consumer juicers the consensus, along with some good anecdotal evidence, seems to strongly indicate that centrifugal juicers generally yield juice with the greatest oxidative damage, followed by masticating juicers (such as the Champion and the crushing stage of some Norwalk juicers), which tend to produce a juice with significantly  less oxidative damage.  However, the twin-gear juicers (such as the Green Life and the Angel) seem to produce the least heating and least exposure to oxygen, yielding the highest quality juices.  When the current author switched from a masticating juicer to a Green Life twin-gear juicer in late 2000 at the urging of Aaonus Vonderplanitz and several long-time RVAFers, he noticed a significant improvement in the quality of the juice.

A number of persons in the raw foods world have come up with guidelines for the quality of each class of juicer, and, while there is some variance, most seem to agree that:

  • the juice from a centrifugal juicer must be consumed almost immediately after juicing to take advantage of nutrients before serious oxidative damage can progressively damage nutrients; such oxidation, when severe, often yields a brownish color in the juice
  • the juice from a masticating juicer may be refrigerated and stored for up to 24 hours, while maintaining an acceptable nutrient quality
  • the juice from a twin-gear juicer may be stored under refrigeration for up to at least three days, while maintaining an acceptable nutrient quality.  Indeed, Aajonus Vonderplanitz has done studies which have shown that after 78 hours (3 days and 6 hours) the nutrients in the juice from a Green Life juicer still retained at least 82% of their original potency.
Therefore, many "serious" devotees of juicing seem to end up using twin-gear juicers in order to yield higher juice quality and the ability to juice vegetables in quantity and then store the juice in 8-ounce or 16-ounce tightly sealed containers (see below) under refrigeration for a few (3+) days, while still maintaining high nutrient quality.  Recently, a fair number of raw foodists who eat raw vegetable and animal diets (RVAF diets), including this author, have been adding small amounts of a proprietary hydride (H-) donor antioxidant (MegaH aka MegaH-™) to the raw juice before storage to decrease oxidative damage over time and to increase useful storage lifetime of the juice.  This paper will address that as well.

Further guidelines, regarding storage of juice, will appear below.
 

Introduction to Some Laboratory Studies and Trials

The current author performed several preliminary trial studies in late 2000 and early 2001 regarding quality of raw juice under storage, and completed a longer study in early 2001 to measure oxidative degradation over time of refrigerated fresh raw vegetable juice from a Green Life juicer, and also to look at the difference in degradation between untreated raw juice and juice (from the same source batch) which had been treated with an earlier version of a product currently marketed as MegaH® (aka MegaH-).  The results of the longer study are presented in detailed format (but in "technicalese" rather than plain English!) on another page on this site.  However, as indicated above, the results of that study and other trials are presented in this paper (on this page) in simpler summary format.

For all studies, the primary measure of oxidative degradation of the raw juice was oxidation-reduction potential (also called "redox") or ORP.  ORP is measured with an ORP meter, and such meters range in cost from $89 to $2,000.  (The ORP meters used in this study were laboratory-quality and were priced in the range of $300 apiece.)  ORP measures the degree of oxidation or reduction (reduction is absence of oxidation and is tantamount to anti-oxidant power) of a water-based substance, and the ORP scale ranges from -1,200 (strongly reducing) to +1200 (strongly oxidizing.)   For example, hydrogen peroxide from your medicine cabinet or chlorine bleach from under your sink (mixed with some water) would both show an ORP near +1,200, indicating that they are potent oxidizers.  On the other hand, so-called "alkaline" ionized water from a home water ionizer would read an ORP of from -150 to -800, indicating moderate to strong reducing (antioxidant) properties.

Most raw organic green vegetable juices from a good juicer will show an initial ORP from -100 through +160, indicating a fairly good store of primitive (reducing) antioxidants in the juice (the pH will usually be about 5.6 to 5.9, indicating presence of plant acids).  Raw organic carrot juice will sometimes show an ORP as low as -170 to -200 (and a pH of about 6.8 or higher, since carrots are not as acid as some other vegetables), as will some raw organic wheatgrass juice.  However, most green juices and vegetable juice mixes show an ORP between -100 and +160.  As a juice ages and gradually oxidizes (e.g., due to any of these factors: heat, exposure to air and light, time), the ORP will climb steadily, finally reaching a "settling" zone of perhaps +350 to +450.  As a juice oxidizes, it steadily loses nutrient value.  In general, one would wish to see raw organic green juices in storage remain at or below an ORP of +180, although one could safely say that an ORP of up to perhaps 210 might be acceptable under some circumstances.  A better way of stating the matter might be this: you do not want to see the ORP rise (toward +1,200) more than 80 counts over the initial value.

Secondary measures of juice quality and oxidative damage were observations of smell, taste and appearance, made by the researcher at each test period.  pH (acid-alkaline), juice temperature, and electrical conductivity were measured as well at each test period, for reference purposes.

The longer and detailed study described above used two test batches of organic raw green juice from a twin-gear juicer, each drawn from the same well-mixed source batch and strained (to remove particles).  One test batch was untreated raw juice, while the other batch, labeled the control batch, was treated by adding 250 mg (1 capsule equiv.) of (an early form of) MegaH per quart as a prophylactic antioxidant.  The source batch was one gallon of fresh raw organic vegetable juice, juiced in a Green Life twin-gear juicer, using fresh organic pre-washed (winter-time) vegetables in the following approximate ratios by weight :
 
celery
45%
parsley
18%
cucumber
18%
carrots
9%
beets
9%
habanero pepper (1 ounce raw)
trace

The two test batches of juice were stored in one-pint heavy-duty, wide-mouth Nalgene (TM) HDPE thick-walled bottles in a 39 degree F refrigerator.  ORP, smell, taste and appearance were measured approximately every 1.5 to 2 days, or more frequently as needed.  These plastic bottles were chosen because they offer almost as much impermeability to oxygen and other substances as glass, and yet are far less fragile.  (Indeed, the current author uses ten of these pint bottles to store his day-to-day green juice after juicing.)

Since about 1.5 ounces of juice was to be drawn from each bottle at each test period, it is obvious that the level of the juice in the bottles would steadily decrease, thus increasing the amount of "headspace" and thus dead air, above the juice. Since air is about 21% oxygen, this air above the juice surface is a potent and major force in accelerating oxidation over what would be seen in juice stored in a container with little or no air space above the juice (e.g, a full bottle, well-sealed).  If this were allowed to happen, the results of the study would show greater rate of oxidative degradation than would be seen in the "real world", where the juice would be stored in an 8 or 16 ounce bottle and would be used all at once or at least over no more than an 8-hour period.  Therefore, as the juice level in each test bottle declined, the headspace (dead air space) above the juice was flushed and filled with an inert gas (helium gas) prior to sealing the bottle (this reduced the amount of oxygen in the headspace to less than 1%.)
 

Brief Summary of Study Findings

As stated above, if you wish to see the detailed longer study, please go to that page , although it is written more in "technicalese" than is this page.

Briefly, here is what was found:

Both batches of juice started with an ORP of +090.  After MegaH (aka MegaH-™) was added to the control batch, the ORP (after 3 minutes) read -590.

The untreated juice showed relatively modest oxidation over the first 3.5 days, yielding a final ORP of about +156 after 3.5 days. In the opinion of this author, this indicates that most of the nutrients in the juice were still intact.  Further, all secondary measures (smell, taste, appearance) still rated a score of "5" on a scale of 1 to 5 after 3.5 days.

The treated juice, which started at an ORP of -590, ended up at -529 after 3.5 days, and -499 after 7 days.  In the opinion of this author, this indicates that almost all of the nutrients in the juice were still intact at both 3.5 days and 7 days.  Further, all secondary measures (smell, taste, appearance) still rated a score of "5" on a scale of 1 to 5 after 3.5 days and after 7 days.  Minor degradation of taste and smell was noted in this batch after 8 days; this was likely due to slow and steady bacterial action, resulting in decomposition and slight "fermentation". This is not necessarily harmful.

Due to the incredibly strong reducing effect in the treated juice after even 7 days, the author has decided that far less MegaH may be used, and subsequent trials have shown that just 250 mg per gallon (or an amount 1/4 of that used in the study) is all that is needed to bring the juice to an initial ORP in the -290 range and keep it below -200 over 7 days, which is more than adequate protection for the juice.  It should be noted that the current author often makes 1.5 to 1.8 gallons of raw juice at once and stores it for up to 7 days in the refrigerator prior to use.
 

Some Guidelines on Juice Storage

Based upon the trials and studies described above, and upon general current knowledge, here are recommendations for storing fresh raw vegetable juice beyond the time of juicing:

    • When juicing, use a twin-gear juicer only, or a twin-gear juicer followed by a Norwalk press only.
    • When juicing for storage, try to use only fresh organic vegetables.  Studies show that these usually start out with higher levels of antioxidants, as well as higher levels of minerals and other nutrients..
    • Immediately after juicing, juice must be decanted into small bottles and then immediately refrigerated.  If storing more than 4 bottles in the refrigerator at once, consider placing a few refrigerant gel packs from the freezer near them to speed the chilling process.
    • The juice must be stored in thick-walled plastic HDPE bottles or glass bottles, each with tight-fitting, air-tight, screw-cap seals.
    • The best plastic storage containers seem to be widemouth 8 and 16 ounce Nalgene containers (they usually are milky in color) with screw caps (usually blue) which fit tightly.  These containers are sold in sporting goods stores for carrying water for camping; these containers have thick HDPE walls, and the screw caps fit tightly, forming an airtight seal.
    • The best glass storage containers seem to be those usually recommended by Aajonus Vonderplanitz -- 8-ounce and 16-ounce glass "jelly" canning jars made by Ball, with tight-fitting metal screw lids.
    • Thin-wall plastic containers such as those in which fruit smoothies are sold, or the the thin plastic jugs in which milk is sold, are unusable due to the thin plastic walls, which allow too-rapid an incursion of oxygen as well as too-rapid an escape of the primary antioxidants (H- ions and the H2 breakdown products), as well as the fact that the caps allow some air incursion as well.
    • The bottles must be filled all the way to the top, leaving little or no airspace at top.
    • The size of the bottle or container must be small enough that once it is opened and some contents used, the remainder of the contents must be used within 8 hours to prevent oxidative damage.  Thus, for most users, 8 ounce or 16 ounce containers or bottles will be needed.   Do not use large containers, as the airspace above the juice, as the container is slowly emptied over time, will allow rapid degradation of juice due to presence of oxygen in the air as well as other factors.
    • Again, it bears repeating: DO NOT use thin-walled containers such as those in which milk is sold in stores, or in which carrot juice and smoothies are sold in natural foods stores.  DO NOT use large containers.  DO NOT leave airspace over juice of more than 1 to 3 mm.
    • If you will be storing the juice for 3.5 days or less (and you started with organic vegetables and used a twin-gear juicer), then it appears that you can safely store the juice as-is, without any added antioxidants, although it appears the addition of MegaH™ (aka MegaH-™) as an antioxidant will help further improve quality.
    • If you plan on storing the juice for longer than 3.5 days, or have used non-organic vegetables, or wish even fresher juice quality, then this author recommends use of  MegaH (aka MegaH-™) as an antioxidant at the rate of 250 mg (1 capsule equiv.) per gallon, well-mixed into the bulk container or pitcher before decanting into bottles.  This should extend the useful life of the juice to at least 7 days from time of juicing.


Final Notes

It will be noted that the pH of the fresh raw juice is mildly acidic, falling in the pH range of 5.5 to 6.0.  This is to be expected (it is often even far more acidic with fresh raw fruit juices) and is simply due to the presence of various plant acids.  It will also be noted that the pH of the MegaH-treated batch was slightly higher than that of the control batch: this is due to the mildly-alkaline pH-buffering action of MegaH.

It will further be noticed that the pH of periodic samples from both batches, after stabilization, show a mild trend over time to increase.  This increase is usually due to long-term slow changes in chemical equilibrium in the juice while in storage, and also to the slow but constant action of decay microorganisms as they digest juice components and thus slightly shift the acid-alkaline balance.

note: The thick-wall Nalgene (TM) HDPE containers and thick screw caps, which form an airtight and sturdy seal, offer an impermeability to moisture and oxygen only slightly less than that of a glass container of similar capacity and dimensions, while offering far less vulnerability to breakage.   Use of glass containers with airtight lids would yielded have yielded slightly lesser oxidative degradation over time than observed with the HDPE containers, due to a slightly lower rate of incursion of oxygen through walls of the glass container.
 

Final Conclusions

From the results observed here, which are in harmony with earlier studies done at this laboratory, it appears that the rate of oxidative degradation of the untreated fresh raw juice (control batch) was relatively minimal over the first 3 days, and that the juice could be expected to have retained a large percentage of nutrient quality over the first 3.5 days.  The degree of degradation was especially minimal over the first two days.  It is the opinion of the current author that the juice still retains a very large percentage of nutrient quality after 3.5 days.

From the experimental results observed here for the MegaH-treated batch (the experimental batch), the degree of apparent oxidative damage to the treated juice after even 7 days appeared to be extremely minimal.  Note that after even 8 days the ORP remained in a strongly reduced range of -485.  It is the opinion of the current author that the treated juice still retains a very large percentage of nutrient quality after 6 days.  However, after observing the relatively strongly-reducing environment as shown by ORP in the -520 range, the author believes that for day-to-day preservation of raw juices, an amount of MegaH equivalent to only 1/4 the amount of MegaH used may be needed in order to yield a strong level of antioxidant protection for the juice.  A rate 1/4 of the present amount would be 250 mg MegaH (1 capsule equiv.) per 4 liters (~ 1 gallon) of juice, or 63 mg per liter (~ 1 quart).  Subsequent trials have shown that even an amount 1/4 the amount used in this study appear to be fully adequate to protect the juice from oxidative damage, yielding a starting ORP in the range of -290.
 



*Vinny Pinto, MA, Enhanced Vitality Research.

Notes: study performed in mid-March, 2001. Nominal refrigeration storage temperature was 39 degrees F, with average deviation of +/- 2 degrees or less.

All ORP and pH measurements were performed with a laboratory-grade microprocessor-controlled instrument with separate electrodes for measurement of ORP and pH, and all measurements were checked with a second laboratory-grade instrument for accuracy.  All ORP electrodes were rinsed after each use in cold water, then soaked for 10 min. in an acidic, oxidizing water solution (pH = 2.4; ORP = +1,150) to clean the electrodes and reverse any ion penetration/degradation of electrode shell, followed by rinse in cold water prior to storage.  Failure to clean electrodes will result in progressive degradation of ORP electrode, resulting in regression of ORP readings toward a low positive range (~ +300).

Decanting of liquid from the control and experimental batch bottles for periodic measurement resulted in steady lowering of liquid surface below bottle cap, resulting in increasing headspace in container above liquid surface which would have been normally occupied by ambient room air containing 20% - 21%  O2, offering the potential of accelerated oxidative degradation over liquid stored in a filled bottle with little or no (3 mm or less) headspace allowing accumulation of air.  Thus, to reduce this exposure to O2 in the headspace, all headspace (dead air space) above liquid in storage containers was flushed with an inert gas after each opening/decanting and prior to subsequent return to refrigerated storage .   The inert gas used for flushing and filling headspace in container was helium gas (He, 99.997% tech. grade), yielding a measured O2 concentration of  < 1% in headspace after flushing/filling, as measured with an oxygen probe in test trials conducted prior to this study.

Storage containers were NALGENE (TM) brand widemouth food-quality thick-wall HDPE storage containers with screw caps, with  nominal 500 ml (1 pint) capacity and actual capacity of ~570 ml.  These containers are commonly available via scientific catalogs and in many camping and sporting goods stores, sold as leakproof, heavy-duty bottles for storage of liquids in rough environments.

The thick-wall HDPE containers and thick screw caps, which form an airtight and sturdy seal, offer an impermeability to moisture and oxygen only slightly less than that of a glass container of similar capacity and dimensions, while offering far less vulnerability to breakage and/or leakage.
 
   
MegaHydrinMegaH™ and  MegaH-™  are a registered trademarks owned by Flantech Group.
    Nalgene® is a registered trademark owned by Nalge Nunc International. 


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