# Domestic Use Simulation and Secondary Shelf Life Assessment of Industrial _Pesto alla genovese_
###### Abstract  
The secondary shelf life (SSL) is defined as the time after package opening during which the food product retains a required level of quality. The SSL, indicated in labels as \"best if used within \(x\) days after opening\", could lead to domestic food waste if not correctly evaluated. In this context, the SSL of two brands of industrial shelf-stable pesto products (with an indicated SSL of 5 days) was studied through a domestic use simulation performed in five households under two scenarios simulating real opening and storage conditions[PERSON] The quality of pesto after opening was assessed through microbiological and sensory analyses, determination of instrumental colour parameters, pH and volatiles profiling. For both pesto sauces tested, a SSL \(\geq\) 20 days was proven. Irrespective of the intensity of use (scenarios 1 and 2), the pesto was microbiologically stable: the maximum count for total aerobic mesophilic bacteria (TMB) observed during 20 days of storage was \(9.64\pm 1.7\times 10^{2}\) CFU/g, starting from a commercially stable product. Colour parameters L* and [PERSON] Domestic Use Simulation and Secondary Shelf Life Assessment of Industrial _Pesto alla genovese. Foids_**2021**, 10, 1948. [[https://doi.org/10.3390/foods10081948](https://doi.org/10.3390/foods10081948)]([https[PERSON]doi.org/10.3390/foods10081948](https://doi.org/10.3390/foods10081948))  
and supply chains, including post-harvest losses\". The most recent estimates report that 17% of overall food production is wasted [5]. Most of this waste is produced in the downstream of the chain, especially at the household level: available data range from 33-38% [6], through 45% [7] to 61% of total FLW [5]. Recent evidence [5] has shown that consumer food waste has been significantly underestimated and that figures related to food waste at consumer and food service level (also referred to as \"avoidable food wastes\") are more than twice as much as previously estimated [6]. It should be highlighted that domestic food waste: (i) cannot find alternative uses; (ii) represents the highest [PERSON] of total FLW and (iii) is responsible for the highest environmental impact, since wasted products represent the highest level of resource consumption and emissions. Indeed, the resource consumption necessary for food production is in vain when food is lost or wasted and misses its goal of human consumption [8; 9]. Given the need for FLW prevention and based on the awareness of the importance of domestic food waste [10], it is urgent to adopt effective mitigation measures. Household food waste reduction could be achieved by the downsizing of packages. Smaller packages, indeed, reduce the probability of not being able to consume the product within an appropriate time. However, this approach brings about a higher consumption of packaging materials per food unit. In many cases, it is the overly short secondary shelf life (SSL), i.e., the timespan from the first opening to unacceptability, that turns food products into wastes. This timespan, also referred to as \"period after opening\" (PAO) is mandatory for some cosmetics [11]; for foods, it is usually communicated to consumers through the package label in terms of instructions for use after the first opening with sentences such as \"after opening, store refrigerated and consume within \(x\) days\", where \(x\) ranges from 24 h to a few days, depending on the product category and, within the same product category, depending on the producer. Such indications, however, does not have any scientific support and may even mislead consumers, thus contributing to foods which are still perfectly suitable for consumption being discarded. _Pesto alla genovese_ is a traditional Italian sauce made from basil, olive oil, grated hard cheese, pine seeds, salt, and garlic commonly used as a dressing for pasta. It is widely available as a shelf-stable product in glass jars, with a shelf life of 2-3 years; however, its stability after opening has never been assessed.