Vol.:(0123456789) 1 3 Journal of Food Measurement and Characterization https://doi.org/10.1007/s11694-019-00224-2 ORIGINAL PAPER Respiration rate and shelf‑life study of Crotalaria longirostrata (chipilín) Dolores Rovira 1  · Claudia Alfaro 1  · Violeta Martínez 1  · Isela Menjívar 1 Received: 5 February 2019 / Accepted: 24 July 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract The respiration rate and the shelf-life were studied on Crotalaria longirostrata, an edible leaf cultivated on the Central American region, locally known as chipilín. Besides being a native plant in El Salvador, chipilín is a commercialized food product. In order to obtain experimental data of respiration rates, a closed chamber approach was employed at temperatures of 6, 20 and 30 °C. The experimental data obtained was ft to a two-parameter non-exponential equation to obtain the res- piration rates in terms of CO 2 and O 2 changes over time. The gas concentration results were also ft to an enzyme kinetics respiration model of the Michaelis–Menten type. Furthermore, the respiration rates from the enzyme kinetics model were used to determine the temperature efect on the respiration. This study also provides results of the shelf-life of the unpacked and packed chipilín with diferent materials, low density polyethylene (LDPE) and polypropylene (PP), by using a sensory panel and ftting data to the Weibull’s probabilistic distribution. Overall results show that the enzyme kinetics model, based on uncompetitive inhibition of CO 2 , applies very well to chipilín. The shelf life study results indicated that packaging in LDPE and PP bags increased chipilín shelf life by 3.7 and 2.5 times respectively, compared to storage without packaging. Keywords Respiration rate · Enzyme kinetics · Weibull hazard · Shelf life · Crotalaria longirostrata · Chipilin Introduction In recent years, the integration of international trades and the growth in emigration has increased the demand of nos- talgic foods that come from diferent parts of the world. For instance, Tanner [1] found out that during 2013 there was an 18.4% growth in the demand for specialty products of Latin and Mediterranean cuisine and a 13.1% increase in shelf- stable fruits sales in the United States, and suggested that this upward trend may continue and spread to other regions over the next few years. In addition, almost 20% of Salvadorans are living abroad [2] and their potential interest on consuming their native food, represents a favorable scenario to export food products from El Salvador, particularly some native fruits and vegeta- bles. However, the satisfactory export of these products is highly dependent on storage during the postharvest handling. Therefore, the improvement of the existing storage technolo- gies becomes of interest to increase shelf-life. A Salvadoran edible leaf that is very common and highly commercialized in the Central American region is Crota- laria longirostrata, locally known as chipilín. According to Martinez [3] and Elias [4], this is a 1.5 meters edible veg- etable native to El Salvador that grows in clay loams and sandy soils and can be found in an altitude ranging between 10 and 1960 meters above sea level and a temperature range of 16–32 °C. Martinez [3] highlights the large contents of calcium, iron, thiamine, ribofavin and ascorbic acid and its sizable production in El Salvador, which was reported as more than three thousand tones between 2007 and 2008 [5]. Fresh products are perishable commodities and generally have short shelf-life. Their deterioration is associated with the physiological and biochemical activities and starts at the harvesting time [6]. Living cells of harvested plants respire continuously, utilizing oxygen (O 2 ) and releasing carbon dioxide (CO 2 ). The respiration rate depends, among other parameters, on the storage temperature and the concentration of O 2 and CO 2 . Generally, there is an inverse relationship between respiration rates and the postharvest life of fresh vegetables [7]. * Dolores Rovira mrovira@uca.edu.sv 1 Departamento de Ingeniería de Procesos y Ciencias Ambientales, Universidad Centroamericana José Simeón Cañas, San Salvador, El Salvador