Effects of Chitin and Its Derivative Chitosan on Postharvest Decay of Fruits: A Review

Considerable economic losses to harvested fruits are caused by postharvest fungal decay during transportation and storage, which can be significantly controlled by synthetic fungicides. However, considering public concern over pesticide residues in food and the environment, there is a need for safer alternatives for the control of postharvest decay to substitute synthetic fungicides. As the second most abundant biopolymer renewable source in nature, chitin and its derivative chitosan are widely used in controlling postharvest decay of fruits. This review aims to introduce the effect of chitin and chitosan on postharvest decay in fruits and the possible modes of action involved. We found most of the actions discussed in these researches rest on physiological mechanisms. All of the mechanisms are summarized to lay the groundwork for further studies which should focus on the molecular mechanisms of chitin and chitosan in controlling postharvest decay of fruits

ネコ ノ スイブン セッシュリョウ ト ニョウリョウ ニョウ ヒジュウチ ニ カンスル ケンキュウ

Domestic cats (Felissilvestriscatus ) are known to have lesser and hypertonic urine excretion(urine volume: 22–30 mL/kg per day; specific gravity: 1.015–1.050) than those of domestic dogs( Canislupus familiaris); urine volume: 24–40 mL/kg perday; specific gravity: 1.015–1.040). These have been implicated as factors for feline incidence of struviteurolithiasis and felinelower urinary tract disease, which are diseases that affect the bladder or urethra. We conducted comparative studies on therelationship between fluid intake and urine volume/urine specific gravity under 2 conditions—diet (condition A) comprising"dry food"( 5.6% moisture) and ad libitum drinking water and diet( condition B) comprising" wet food"( 74.8% moisture) andad libitum drinking water—in acclimated cats( n=7) kept separately in cat cages in an animal rearing room at 25°C. The perdiem water intake (apparent water intake) in condition A was on an average 66.9 ± 22.1(mL), while the totalfluid intake (absolute water intake), which is the sum of the amounts of water in the food and the water intake, was on anaverage68.2 ± 23.3(mL).Further, the average water intake under condition B was only 22.7 ± 20.13( mL), but the absolutewater intake was on average 95.6 ± 37.6( mL), meaning that wet food resulted in a higher absolute water intake amountthan dry food. Regarding the urine volume and the urine specific gravity, urine volume and urine specific gravity with the dry food diet(condition A) were 28.8 ± 11.8 (mL) and 1.049 ± 0.01, respectively, but the mean urine volume and urine specific gravityunder condition B were 49.5 ± 31.4(mL) and 1.030 ± 0.01, respectively, showing that compared to the dry food group, thewet food group had a significantly higher urine volume and lower urine specific gravity. The present study proves that in an average rearing environment, the urine volume does not increase and urine specificgravity is hypertonic when the cats are provided dry food diet, despite increase in the apparent water intake. Further, theurine volume increases and urine specific gravity decreases when the cats are provided wet food diet( canned or pouched),although the apparent water intake is low. The present study shows that differences in the diet are factors for the increasedincidence of struviteurolithiasis and FLUTD in cats