Water Activity, Shelf Life and Storage

2017 ◽  
Vol 80 (6) ◽  
pp. 940-946 ◽  
Author(s):  
Yangjunna Zhang ◽  
Susanne E. Keller ◽  
Elizabeth M. Grasso-Kelley

ABSTRACT Tahini, a low-moisture food that is made from sesame seeds, has been implicated in outbreaks of salmonellosis. In this study, the fate of Salmonella was determined through an entire process for the manufacture of tahini, including a 24-h seed soaking period before roasting, subsequent grinding, and storage at refrigeration temperature. Salmonella populations increased by more than 3 log CFU/g during a 24-h soaking period, reaching more than 7 log CFU/g. Survival of Salmonella during roasting at three temperatures, 95, 110, and 130°C, was assessed using seeds on which Salmonella was grown. Salmonella survival was impacted both by temperature and the water activity (aw) at the beginning of the roasting period. When roasted at 130°C with a high initial aw (≥0.90) and starting Salmonella populations of ∼8.5 log CFU/g, populations quickly decreased below detection limits within the first 10 min. However, when the seeds were reduced to an aw of 0.45 before roasting at the same temperature, 3.5 log CFU/g remained on the seeds after 60 min. In subsequent storage studies, seeds were roasted at 130°C for 15 min before processing into tahini. For the storage studies, tahini was inoculated using two methods. The first method used seeds on which Salmonella was first grown before roasting. In the second method, Salmonella was inoculated into the tahini after manufacture. All tahini was stored for 119 days at 4°C. No change in Salmonella populations was recorded for tahini throughout the entire 119 days regardless of the inoculation method used. These combined results indicate the critical importance of aw during a roasting step during tahini manufacture. Salmonella that survive roasting will likely remain viable throughout the normal shelf life of tahini.


1994 ◽  
Vol 57 (10) ◽  
pp. 882-886 ◽  
Author(s):  
FADI M. ARAMOUNI ◽  
KARIM K. KONE ◽  
JEAN A. CRAIG ◽  
DANIEL Y. C. FUNG

The safety of a home-style canned quick bread was investigated using spores of Clostridium sporogenes putrefactive anaerobe (PA) 3679. Baking was done at 177°C for 30, 40 and 50 min, at 191°C for 45, 50 and 55 min, and at 204°C for 40, 45 and 50 min. Products were analyzed for pH, water activity (aw) and vacuum level. The microbial quality of the products was determined before and after baking. Of the products baked at 177°C, some were stored for 90 days at room temperature (23 to 25°C) or in an incubator at 35°C to study their shelf-life. Inoculated and endogenous vegetative cells and their spores were counted before and after baking and after storage using Fung's Double Tube method. Results showed germination of endogenous spores in uninoculated products after baking at 177°C for 30 min and storage at 35°C for 90 days. Survival of inoculated C. sporogenes PA 3679 was detected for all baking and storage treatments. Further work is recommended to determine safe processing procedures for this type of product.


2020 ◽  
Vol 8 (2) ◽  
pp. 134-142
Author(s):  
Salma Shafrina Aulia ◽  
Budi Setiawan ◽  
Tiurma Sinaga ◽  
Ahmad Sulaeman

Background: Instant pumpkin cream soup enriched with tempeh had fulfilled 10% Recommended Dietary Allowances (RDA) for elderly so that it can be used as an easy-to-serve snack, but decreasing quality of instant cream soup will be happened if the instant cream soup was stored for a long time. Objectives: This study aimed to analyze quality of water content, water activity and lipid oxidation in instant pumpkin cream soup during storage and estimated the shelf life of pumpkin cream soup enriched with tempeh.Method:  Quality storage was analyzed using of water content, water activity (aw) and lipid oxidation. Estimation of shelf life was analyzed using Arrhenius Accelerated Shelf Life Testing (ASLT) model.Results: The results showed that the water content, aw levels and lipid oxidation of instant pumpkin cream soup increased during the storage period. The critical parameter used in this study was lipid oxidation. Instant cream soup without the addition of tempeh can last 447 days  while the cream soup with the addition of tempeh has a shelf life of 433 days.Conclusion: Quality of instant pumpkin cream soup decreased during the storage period and it would be expired over a year.


2017 ◽  
Vol 37 (3) ◽  
pp. 440-448 ◽  
Author(s):  
Soohyun Cho ◽  
Sun Moon Kang ◽  
Pilnam Seong ◽  
Geunho Kang ◽  
Youngchoon Kim ◽  
...  

Author(s):  
Siti Hajar Ariffin ◽  
Rosnah Shamsudin ◽  
I. S. M. A. Tawakkal

Dabai (Canarium odontophyllum) or also known as ‘Sarawak olive’ is one of the potential indigenous seasonal fruits commonly found in Sarawak. Due to its high nutritional contents, it has wide potential to be marketed locally and exported internationally. Dabai is very delicate and highly perishable. The shelf life of dabai is usually 3 days when stored in room temperature (27°C). Improper storage and handling lead to the reduction of quality and shelf life of the fruit throughout storage. There is still limitation on the information of postharvest, storage and handling, quality and shelf life of dabai. Studies on quality and shelf life affected by storage treatment and packaging are necessary in optimising shelf life and minimising quality loss of the fruit. This could ensure further potential development of the fruit locally and internationally.


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