106
(Lopez-Briones et al. 1992), drying (Izli and Isik 2014), freezing (Murr and Morris
1975), soaking in saline or acid solution (Cliffe-Byrnes and O’Beirne 2008), and
canning (Vivar-Quintana et al. 1999).
Storage time can be extended for 3–6 months by soaking the mushrooms in
acidic or saline solutions, which help extend shelf life and maintain their color. The
mushrooms are washed in plain water before dipping into the saline solution. The
mushrooms are then put in the containers and covered with the saline solution.
Mushroom preservation through industrial canning technology is used in many
countries around the world. The process of producing canned RSM includes preliminary processing, blanching, stacking, sterilization, cooling, labeling, and packaging. In order to produce canned mushrooms of good quality, it is necessary to
process harvested mushrooms as soon as possible. In case of unavoidable delay,
mushrooms should be stored at 4–5 °C until processed.
However, all the other preservation methods result in inferior mushroom eating
quality compared to that of fresh mushroom, in terms of the original flavor, color,
hardness, and so on. Extending the shelf life of fresh mushroom beyond 3 days is
most important, as illustrated in the case of the Mekong Delta in Vietnam. In the
local market, mushrooms are consumed as a fresh vegetable with the price normally
fluctuating from 2 to 4 US$ kg
−1
at the first and 15th day of the lunar month. A small
portion of salted or dried RSM is also exported at 2 US$ kg
−1
, but is not as much
appreciated as fresh mushrooms. For estimating consumer trends, we can look at the
American market. In 2012, the share of fresh mushrooms was 87% in quantity and
93% in value; the remaining minor portion is processed mushroom, with a farm gate
price of only one half compared to that of fresh mushroom (Phan-Hieu-Hien 2017).
The price of fresh RSM at US supermarkets in 2013 was about 10 $US kg
−1
,
while that of salted mushroom was only 5 $US kg
−1
(personal communication with
Mr. Le Duy Thang, mushroom expert). From farms in Vietnam to US supermarkets,
fresh RSM needs a minimum of 8 days to “travel”, including 2–3 days through
customs and 2–3 days at supermarkets before reaching consumers. The 8-day shelf
life of fresh mushroom is the greatest constraint to boost mushroom production, or
indirectly to increase the use of rice straw. Luckily after decades of deadlock, some
research results are promising (Dhalsamant et al. 2018). Factors to help ensure a
successful 8-day storage cycle include: (1) a suitable temperature, say 12 °C; (2) a
controlled-atmosphere packaging, which is balanced between oxygen and carbon
dioxide content; and (3) a chemical pretreatment, such as CaCl 2 . More in-depth
research is needed in parallel with pilot testing for economic performance.
6.7 Summary and Recommendations
Producing RSM is a sustainable option for adding value to rice production and
reducing environmental harm through avoiding the burning of rice straw in the field.
Growing outdoor RSM is a traditional practice with low investment costs but generates low yield and incurs high risk because it is strongly affected by changes in the
L. V. Thuc et al.
(Lopez-Briones et al. 1992), drying (Izli and Isik 2014), freezing (Murr and Morris
1975), soaking in saline or acid solution (Cliffe-Byrnes and O’Beirne 2008), and
canning (Vivar-Quintana et al. 1999).
Storage time can be extended for 3–6 months by soaking the mushrooms in
acidic or saline solutions, which help extend shelf life and maintain their color. The
mushrooms are washed in plain water before dipping into the saline solution. The
mushrooms are then put in the containers and covered with the saline solution.
Mushroom preservation through industrial canning technology is used in many
countries around the world. The process of producing canned RSM includes preliminary processing, blanching, stacking, sterilization, cooling, labeling, and packaging. In order to produce canned mushrooms of good quality, it is necessary to
process harvested mushrooms as soon as possible. In case of unavoidable delay,
mushrooms should be stored at 4–5 °C until processed.
However, all the other preservation methods result in inferior mushroom eating
quality compared to that of fresh mushroom, in terms of the original flavor, color,
hardness, and so on. Extending the shelf life of fresh mushroom beyond 3 days is
most important, as illustrated in the case of the Mekong Delta in Vietnam. In the
local market, mushrooms are consumed as a fresh vegetable with the price normally
fluctuating from 2 to 4 US$ kg
−1
at the first and 15th day of the lunar month. A small
portion of salted or dried RSM is also exported at 2 US$ kg
−1
, but is not as much
appreciated as fresh mushrooms. For estimating consumer trends, we can look at the
American market. In 2012, the share of fresh mushrooms was 87% in quantity and
93% in value; the remaining minor portion is processed mushroom, with a farm gate
price of only one half compared to that of fresh mushroom (Phan-Hieu-Hien 2017).
The price of fresh RSM at US supermarkets in 2013 was about 10 $US kg
−1
,
while that of salted mushroom was only 5 $US kg
−1
(personal communication with
Mr. Le Duy Thang, mushroom expert). From farms in Vietnam to US supermarkets,
fresh RSM needs a minimum of 8 days to “travel”, including 2–3 days through
customs and 2–3 days at supermarkets before reaching consumers. The 8-day shelf
life of fresh mushroom is the greatest constraint to boost mushroom production, or
indirectly to increase the use of rice straw. Luckily after decades of deadlock, some
research results are promising (Dhalsamant et al. 2018). Factors to help ensure a
successful 8-day storage cycle include: (1) a suitable temperature, say 12 °C; (2) a
controlled-atmosphere packaging, which is balanced between oxygen and carbon
dioxide content; and (3) a chemical pretreatment, such as CaCl 2 . More in-depth
research is needed in parallel with pilot testing for economic performance.
6.7 Summary and Recommendations
Producing RSM is a sustainable option for adding value to rice production and
reducing environmental harm through avoiding the burning of rice straw in the field.
Growing outdoor RSM is a traditional practice with low investment costs but generates low yield and incurs high risk because it is strongly affected by changes in the
L. V. Thuc et al.