Blue Diamond® understands the importance of shelf life in the development and marketing of foods. Consumer acceptance depends on many factors such as freshness, flavor, aroma and texture of the finished product. Eleven years of study by Blue Diamond® have unlocked many of the secrets of almond shelf life.
Blue Diamond® Shelf Life Program.
An extensive shelf life program was initiated at Blue Diamond® Growers Almond Research Center in 1986. Since then,hundreds of products have been tested and many other studies are ongoing. Blue Diamond® research has shown that almonds have a relatively long shelf life in comparison to other nut meats.
Our method of monitoring shelf life of various products is based on both objective and subjective quality measurements.
Objective Measurements: Peroxide value, free fatty acids, oxygen, moisture, water activity and induction time as measured by Rancimat™ are monitored.
Subjective Measurements: At the heart of Blue Diamond®’s shelf life program is a sophisticated series of sensory analysis panels which evaluate various product characteristics. This work is done by a trained shelf life panel.
The trained panel monitors products from most studies, and evaluates samples for freshness to determine shelf life. It consists of dedicated Blue Diamond® employees who participate in sensory analysis of almond and other nut meats on a weekly basis. The panel assigns scores to samples based on a scale in which 1 equals fresh and 7 equals very stale. A complete description of the shelf life methodology is available upon request.
Difficult to Determine and No Guarantees.
In measuring the shelf life of any agricultural commodity,it is difficult to assign an absolute value to the storage properties because of:
 Variability in nut crop from year to year;
Changing weather conditions from year to year;
Differences in cultural practices;
Differences in post harvest handling.
All of these factors result in variability in the shelf life of almonds. It is therefore important to understand that the data collected may not fit every situation.
Why Do Almonds Turn Rancid?
Oxygen is the main culprit. When oxygen in the air reacts with unsaturated fat through a process called autoxidation, various breakdown products are formed which can cause off-flavors and other problems.
Other Factors Influencing Shelf Life.
Other factors that influence the rate of deterioration of almond products include the age of the product, roasting, size of pieces, the moisture content, exposure to light and exposure to certain metals. Generally, the greater the surface area, the greater the opportunity for the autoxidation process to proceed, depending on the process used in size reduction of whole almonds. Increases in moisture can result in increases in oxidative and biological processes which in turn lead to a reduction in shelf life. Light increases oxidative processes by initiating free radical formation, and certain metals can increase oxidative processes by acting as catalysis.
Processing methods can also affect shelf life. Cutting, blanching, roasting,the addition of moisture or poor quality roasting oil can all decrease shelf life of almonds. Blue Diamond® research has shown that under ambient storage conditions, dry roasted almonds have a longer shelf life than oil roasted almonds. Antioxidant application or chocolate coating can increase shelf life of almonds. Effective synthetic antioxidants for almonds are: BHA, BHT and TBHQ. A commercial product, mixed tocopherols, is an effective natural antioxidant.
Packaging.
Packaging plays a crucial role in prolonging shelf life. Ideally packaging should provide an effective barrier against oxygen, moisture, light and insects. The exclusion of oxygen is particularly important in roasted products, and oxygen levels between 0.5 percent and 1.5 percent can be achieved with nitrogen flushing. Packaging for raw nuts is also important but far less critical than with roasted products.
Storage Conditions.
Storage conditions are extremely important in optimizing potential shelf life and in guarding against insect infestation. Storage temperatures of 35–45ºF (2-7ºC)can extend the shelf life of all almond products.
Optimum Storage Conditions for Raw Almonds
Moisture Content: <6%;
Temperature: 35–45ºF, 2–7ºC
Relative Humidity (Cold Storage) 55%–65%
Odor-free Environment: Since almonds readily absorb odors, they should never be stored near or exposed to pungent foods or chemicals.
Ambient Air - Room Temperature (75ºF,24ºC) Storage*
| Table 1 |
|
Type
|
Packaging Atmosphere
|
Shelf Life Guidelines**
|
|
Inshell
|
Ambient/Bag
|
36 mos.
|
Whole
|
Ambient/Carton
|
24 mos.
|
Sliced
|
Ambient/Poly Carton
|
36 mos.
|
Diced
|
Ambient/Poly Carton
|
12 mos.
|
Meal
|
Ambient/Poly Carton
|
12 mos.
|
|
Whole
|
Ambient/Poly Carton
|
12 mos.
|
Slivered
|
Ambient/Poly Carton
|
12 mos.
|
Sliced
|
Ambient/Poly Carton
|
18 mos.
|
Diced
|
Ambient/Poly Carton
|
18 mos.
|
Meal
|
Ambient/Poly Carton
|
12 mos.
|
|
|
| Table 2 |
|
Type
|
Packaging Atmosphere
|
Shelf Life Guidelines**
|
|
Whole Natural (Brown)
|
Nitrogen flushed
|
36 mos.
|
Whole Natural Smokehouse®
|
Nitrogen flushed
|
36 mos.
|
Honey Roasted Whole
|
Nitrogen flushed
|
36 mos.
|
Natural Seasoned Whole
|
Nitrogen flushed
|
36 mos.
|
Diced Natural
|
Vacuum packed
|
12 mos.
|
Diced Natural
|
Nitrogen flushed
|
36 mos.
|
|
Whole Natural (Brown)
|
Nitrogen flushed
|
48 mos.
|
Whole Natural
|
Vacuum packed
|
36 mos.
|
Whole Natural
|
Ambient
|
6 mos.
|
Natural Pieces
|
Ambient
|
6 mos.
|
Diced Natural
|
Nitrogen flushed
|
36 mos.
|
Slivered Blanched
|
Ambient
|
6 mos.
|
|
*Cold Storage (35-45ºF, 2-7ºC, relative humidity 55%-65%) prolongs shelf life and prevents insect infestation.
**The information in Table 1 and 2 gives a summary of shelf life data collected to date. This information is relatively conservative and is meant to be used as guidelines, but is in no way a guarantee. Results will vary with roasting conditions.
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